mono/metadata/threadpool-ms.c

   1 /*
   2  * threadpool-ms.c: Microsoft threadpool runtime support
   3  *
   4  * Author:
   5  *      Ludovic Henry (ludovic.henry@xamarin.com)
   6  *
   7  * Copyright 2015 Xamarin, Inc (http://www.xamarin.com)
   8  */
   9
  10 //
  11 // Copyright (c) Microsoft. All rights reserved.
  12 // Licensed under the MIT license. See LICENSE file in the project root for full license information.
  13 //
  14 // Files:
  15 //  - src/vm/comthreadpool.cpp
  16 //  - src/vm/win32threadpoolcpp
  17 //  - src/vm/threadpoolrequest.cpp
  18 //  - src/vm/hillclimbing.cpp
  19 //
  20 // Ported from C++ to C and adjusted to Mono runtime
  21
  22 #include <stdlib.h>
  23 #define _USE_MATH_DEFINES // needed by MSVC to define math constants
  24 #include <math.h>
  25 #include <config.h>
  26 #include <glib.h>
  27
  28 #include <mono/metadata/class-internals.h>
  29 #include <mono/metadata/exception.h>
  30 #include <mono/metadata/gc-internals.h>
  31 #include <mono/metadata/object.h>
  32 #include <mono/metadata/object-internals.h>
  33 #include <mono/metadata/threadpool-ms.h>
  34 #include <mono/metadata/threadpool-ms-io.h>
  35 #include <mono/utils/atomic.h>
  36 #include <mono/utils/mono-compiler.h>
  37 #include <mono/utils/mono-complex.h>
  38 #include <mono/utils/mono-lazy-init.h>
  39 #include <mono/utils/mono-logger.h>
  40 #include <mono/utils/mono-logger-internals.h>
  41 #include <mono/utils/mono-proclib.h>
  42 #include <mono/utils/mono-threads.h>
  43 #include <mono/utils/mono-time.h>
  44 #include <mono/utils/mono-rand.h>
  45
  46 #define CPU_USAGE_LOW 80
  47 #define CPU_USAGE_HIGH 95
  48
  49 #define MONITOR_INTERVAL 100 // ms
  50 #define MONITOR_MINIMAL_LIFETIME 60 * 1000 // ms
  51
  52 /* The exponent to apply to the gain. 1.0 means to use linear gain,
  53  * higher values will enhance large moves and damp small ones.
  54  * default: 2.0 */
  55 #define HILL_CLIMBING_GAIN_EXPONENT 2.0
  56
  57 /* The 'cost' of a thread. 0 means drive for increased throughput regardless
  58  * of thread count, higher values bias more against higher thread counts.
  59  * default: 0.15 */
  60 #define HILL_CLIMBING_BIAS 0.15
  61
  62 #define HILL_CLIMBING_WAVE_PERIOD 4
  63 #define HILL_CLIMBING_MAX_WAVE_MAGNITUDE 20
  64 #define HILL_CLIMBING_WAVE_MAGNITUDE_MULTIPLIER 1.0
  65 #define HILL_CLIMBING_WAVE_HISTORY_SIZE 8
  66 #define HILL_CLIMBING_TARGET_SIGNAL_TO_NOISE_RATIO 3.0
  67 #define HILL_CLIMBING_MAX_CHANGE_PER_SECOND 4
  68 #define HILL_CLIMBING_MAX_CHANGE_PER_SAMPLE 20
  69 #define HILL_CLIMBING_SAMPLE_INTERVAL_LOW 10
  70 #define HILL_CLIMBING_SAMPLE_INTERVAL_HIGH 200
  71 #define HILL_CLIMBING_ERROR_SMOOTHING_FACTOR 0.01
  72 #define HILL_CLIMBING_MAX_SAMPLE_ERROR_PERCENT 0.15
  73
  74 typedef union {
  75         struct {
  76                 gint16 max_working; /* determined by heuristic */
  77                 gint16 active; /* executing worker_thread */
  78                 gint16 working; /* actively executing worker_thread, not parked */
  79                 gint16 parked; /* parked */
  80         } _;
  81         gint64 as_gint64;
  82 } ThreadPoolCounter;
  83
  84 typedef struct {
  85         MonoDomain *domain;
  86         gint32 outstanding_request;
  87 } ThreadPoolDomain;
  88
  89 typedef MonoInternalThread ThreadPoolWorkingThread;
  90
  91 typedef struct {
  92         gint32 wave_period;
  93         gint32 samples_to_measure;
  94         gdouble target_throughput_ratio;
  95         gdouble target_signal_to_noise_ratio;
  96         gdouble max_change_per_second;
  97         gdouble max_change_per_sample;
  98         gint32 max_thread_wave_magnitude;
  99         gint32 sample_interval_low;
 100         gdouble thread_magnitude_multiplier;
 101         gint32 sample_interval_high;
 102         gdouble throughput_error_smoothing_factor;
 103         gdouble gain_exponent;
 104         gdouble max_sample_error;
 105
 106         gdouble current_control_setting;
 107         gint64 total_samples;
 108         gint16 last_thread_count;
 109         gdouble elapsed_since_last_change;
 110         gdouble completions_since_last_change;
 111
 112         gdouble average_throughput_noise;
 113
 114         gdouble *samples;
 115         gdouble *thread_counts;
 116
 117         guint32 current_sample_interval;
 118         gpointer random_interval_generator;
 119
 120         gint32 accumulated_completion_count;
 121         gdouble accumulated_sample_duration;
 122 } ThreadPoolHillClimbing;
 123
 124 typedef struct {
 125         ThreadPoolCounter counters;
 126
 127         GPtrArray *domains; // ThreadPoolDomain* []
 128         MonoCoopMutex domains_lock;
 129
 130         GPtrArray *working_threads; // ThreadPoolWorkingThread* []
 131         gint32 parked_threads_count;
 132         MonoCoopCond parked_threads_cond;
 133         MonoCoopMutex active_threads_lock; /* protect access to working_threads and parked_threads */
 134
 135         gint32 heuristic_completions;
 136         guint32 heuristic_sample_start;
 137         guint32 heuristic_last_dequeue; // ms
 138         guint32 heuristic_last_adjustment; // ms
 139         guint32 heuristic_adjustment_interval; // ms
 140         ThreadPoolHillClimbing heuristic_hill_climbing;
 141         MonoCoopMutex heuristic_lock;
 142
 143         gint32 limit_worker_min;
 144         gint32 limit_worker_max;
 145         gint32 limit_io_min;
 146         gint32 limit_io_max;
 147
 148         MonoCpuUsageState *cpu_usage_state;
 149         gint32 cpu_usage;
 150
 151         /* suspended by the debugger */
 152         gboolean suspended;
 153 } ThreadPool;
 154
 155 typedef enum {
 156         TRANSITION_WARMUP,
 157         TRANSITION_INITIALIZING,
 158         TRANSITION_RANDOM_MOVE,
 159         TRANSITION_CLIMBING_MOVE,
 160         TRANSITION_CHANGE_POINT,
 161         TRANSITION_STABILIZING,
 162         TRANSITION_STARVATION,
 163         TRANSITION_THREAD_TIMED_OUT,
 164         TRANSITION_UNDEFINED,
 165 } ThreadPoolHeuristicStateTransition;
 166
 167 static mono_lazy_init_t status = MONO_LAZY_INIT_STATUS_NOT_INITIALIZED;
 168
 169 enum {
 170         MONITOR_STATUS_REQUESTED,
 171         MONITOR_STATUS_WAITING_FOR_REQUEST,
 172         MONITOR_STATUS_NOT_RUNNING,
 173 };
 174
 175 static gint32 monitor_status = MONITOR_STATUS_NOT_RUNNING;
 176
 177 static ThreadPool* threadpool;
 178
 179 #define COUNTER_CHECK(counter) \
 180         do { \
 181                 g_assert (counter._.max_working > 0); \
 182                 g_assert (counter._.working >= 0); \
 183                 g_assert (counter._.active >= 0); \
 184         } while (0)
 185
 186 #define COUNTER_READ() (InterlockedRead64 (&threadpool->counters.as_gint64))
 187
 188 #define COUNTER_ATOMIC(var,block) \
 189         do { \
 190                 ThreadPoolCounter __old; \
 191                 do { \
 192                         g_assert (threadpool); \
 193                         __old.as_gint64 = COUNTER_READ (); \
 194                         (var) = __old; \
 195                         { block; } \
 196                         COUNTER_CHECK (var); \
 197                 } while (InterlockedCompareExchange64 (&threadpool->counters.as_gint64, (var).as_gint64, __old.as_gint64) != __old.as_gint64); \
 198         } while (0)
 199
 200 #define COUNTER_TRY_ATOMIC(res,var,block) \
 201         do { \
 202                 ThreadPoolCounter __old; \
 203                 do { \
 204                         g_assert (threadpool); \
 205                         __old.as_gint64 = COUNTER_READ (); \
 206                         (var) = __old; \
 207                         (res) = FALSE; \
 208                         { block; } \
 209                         COUNTER_CHECK (var); \
 210                         (res) = InterlockedCompareExchange64 (&threadpool->counters.as_gint64, (var).as_gint64, __old.as_gint64) == __old.as_gint64; \
 211                 } while (0); \
 212         } while (0)
 213
 214 static gpointer
 215 rand_create (void)
 216 {
 217         mono_rand_open ();
 218         return mono_rand_init (NULL, 0);
 219 }
 220
 221 static guint32
 222 rand_next (gpointer *handle, guint32 min, guint32 max)
 223 {
 224         guint32 val;
 225         if (!mono_rand_try_get_uint32 (handle, &val, min, max)) {
 226                 // FIXME handle error
 227                 g_assert_not_reached ();
 228         }
 229         return val;
 230 }
 231
 232 static void
 233 rand_free (gpointer handle)
 234 {
 235         mono_rand_close (handle);
 236 }
 237
 238 static void
 239 initialize (void)
 240 {
 241         ThreadPoolHillClimbing *hc;
 242         const char *threads_per_cpu_env;
 243         gint threads_per_cpu;
 244         gint threads_count;
 245
 246         g_assert (!threadpool);
 247         threadpool = g_new0 (ThreadPool, 1);
 248         g_assert (threadpool);
 249
 250         threadpool->domains = g_ptr_array_new ();
 251         mono_coop_mutex_init (&threadpool->domains_lock);
 252
 253         threadpool->parked_threads_count = 0;
 254         mono_coop_cond_init (&threadpool->parked_threads_cond);
 255         threadpool->working_threads = g_ptr_array_new ();
 256         mono_coop_mutex_init (&threadpool->active_threads_lock);
 257
 258         threadpool->heuristic_adjustment_interval = 10;
 259         mono_coop_mutex_init (&threadpool->heuristic_lock);
 260
 261         mono_rand_open ();
 262
 263         hc = &threadpool->heuristic_hill_climbing;
 264
 265         hc->wave_period = HILL_CLIMBING_WAVE_PERIOD;
 266         hc->max_thread_wave_magnitude = HILL_CLIMBING_MAX_WAVE_MAGNITUDE;
 267         hc->thread_magnitude_multiplier = (gdouble) HILL_CLIMBING_WAVE_MAGNITUDE_MULTIPLIER;
 268         hc->samples_to_measure = hc->wave_period * HILL_CLIMBING_WAVE_HISTORY_SIZE;
 269         hc->target_throughput_ratio = (gdouble) HILL_CLIMBING_BIAS;
 270         hc->target_signal_to_noise_ratio = (gdouble) HILL_CLIMBING_TARGET_SIGNAL_TO_NOISE_RATIO;
 271         hc->max_change_per_second = (gdouble) HILL_CLIMBING_MAX_CHANGE_PER_SECOND;
 272         hc->max_change_per_sample = (gdouble) HILL_CLIMBING_MAX_CHANGE_PER_SAMPLE;
 273         hc->sample_interval_low = HILL_CLIMBING_SAMPLE_INTERVAL_LOW;
 274         hc->sample_interval_high = HILL_CLIMBING_SAMPLE_INTERVAL_HIGH;
 275         hc->throughput_error_smoothing_factor = (gdouble) HILL_CLIMBING_ERROR_SMOOTHING_FACTOR;
 276         hc->gain_exponent = (gdouble) HILL_CLIMBING_GAIN_EXPONENT;
 277         hc->max_sample_error = (gdouble) HILL_CLIMBING_MAX_SAMPLE_ERROR_PERCENT;
 278         hc->current_control_setting = 0;
 279         hc->total_samples = 0;
 280         hc->last_thread_count = 0;
 281         hc->average_throughput_noise = 0;
 282         hc->elapsed_since_last_change = 0;
 283         hc->accumulated_completion_count = 0;
 284         hc->accumulated_sample_duration = 0;
 285         hc->samples = g_new0 (gdouble, hc->samples_to_measure);
 286         hc->thread_counts = g_new0 (gdouble, hc->samples_to_measure);
 287         hc->random_interval_generator = rand_create ();
 288         hc->current_sample_interval = rand_next (&hc->random_interval_generator, hc->sample_interval_low, hc->sample_interval_high);
 289
 290         if (!(threads_per_cpu_env = g_getenv ("MONO_THREADS_PER_CPU")))
 291                 threads_per_cpu = 1;
 292         else
 293                 threads_per_cpu = CLAMP (atoi (threads_per_cpu_env), 1, 50);
 294
 295         threads_count = mono_cpu_count () * threads_per_cpu;
 296
 297         threadpool->limit_worker_min = threadpool->limit_io_min = threads_count;
 298         threadpool->limit_worker_max = threadpool->limit_io_max = threads_count * 100;
 299
 300         threadpool->counters._.max_working = threadpool->limit_worker_min;
 301
 302         threadpool->cpu_usage_state = g_new0 (MonoCpuUsageState, 1);
 303
 304         threadpool->suspended = FALSE;
 305 }
 306
 307 static void worker_kill (ThreadPoolWorkingThread *thread);
 308
 309 static void
 310 cleanup (void)
 311 {
 312         guint i;
 313
 314         /* we make the assumption along the code that we are
 315          * cleaning up only if the runtime is shutting down */
 316         g_assert (mono_runtime_is_shutting_down ());
 317
 318         while (monitor_status != MONITOR_STATUS_NOT_RUNNING)
 319                 mono_thread_info_sleep (1, NULL);
 320
 321         mono_coop_mutex_lock (&threadpool->active_threads_lock);
 322
 323         /* stop all threadpool->working_threads */
 324         for (i = 0; i < threadpool->working_threads->len; ++i)
 325                 worker_kill ((ThreadPoolWorkingThread*) g_ptr_array_index (threadpool->working_threads, i));
 326
 327         /* unpark all threadpool->parked_threads */
 328         mono_coop_cond_broadcast (&threadpool->parked_threads_cond);
 329
 330         mono_coop_mutex_unlock (&threadpool->active_threads_lock);
 331 }
 332
 333 void
 334 mono_threadpool_ms_enqueue_work_item (MonoDomain *domain, MonoObject *work_item)
 335 {
 336         static MonoClass *threadpool_class = NULL;
 337         static MonoMethod *unsafe_queue_custom_work_item_method = NULL;
 338         MonoDomain *current_domain;
 339         MonoBoolean f;
 340         gpointer args [2];
 341
 342         g_assert (work_item);
 343
 344         if (!threadpool_class)
 345                 threadpool_class = mono_class_from_name (mono_defaults.corlib, "System.Threading", "ThreadPool");
 346         g_assert (threadpool_class);
 347
 348         if (!unsafe_queue_custom_work_item_method)
 349                 unsafe_queue_custom_work_item_method = mono_class_get_method_from_name (threadpool_class, "UnsafeQueueCustomWorkItem", 2);
 350         g_assert (unsafe_queue_custom_work_item_method);
 351
 352         f = FALSE;
 353
 354         args [0] = (gpointer) work_item;
 355         args [1] = (gpointer) &f;
 356
 357         current_domain = mono_domain_get ();
 358         if (current_domain == domain) {
 359                 mono_runtime_invoke (unsafe_queue_custom_work_item_method, NULL, args, NULL);
 360         } else {
 361                 mono_thread_push_appdomain_ref (domain);
 362                 if (mono_domain_set (domain, FALSE)) {
 363                         mono_runtime_invoke (unsafe_queue_custom_work_item_method, NULL, args, NULL);
 364                         mono_domain_set (current_domain, TRUE);
 365                 }
 366                 mono_thread_pop_appdomain_ref ();
 367         }
 368 }
 369
 370 /* LOCKING: threadpool->domains_lock must be held */
 371 static void
 372 domain_add (ThreadPoolDomain *tpdomain)
 373 {
 374         guint i, len;
 375
 376         g_assert (tpdomain);
 377
 378         len = threadpool->domains->len;
 379         for (i = 0; i < len; ++i) {
 380                 if (g_ptr_array_index (threadpool->domains, i) == tpdomain)
 381                         break;
 382         }
 383
 384         if (i == len)
 385                 g_ptr_array_add (threadpool->domains, tpdomain);
 386 }
 387
 388 /* LOCKING: threadpool->domains_lock must be held */
 389 static gboolean
 390 domain_remove (ThreadPoolDomain *tpdomain)
 391 {
 392         g_assert (tpdomain);
 393         return g_ptr_array_remove (threadpool->domains, tpdomain);
 394 }
 395
 396 /* LOCKING: threadpool->domains_lock must be held */
 397 static ThreadPoolDomain *
 398 domain_get (MonoDomain *domain, gboolean create)
 399 {
 400         ThreadPoolDomain *tpdomain = NULL;
 401         guint i;
 402
 403         g_assert (domain);
 404
 405         for (i = 0; i < threadpool->domains->len; ++i) {
 406                 tpdomain = g_ptr_array_index (threadpool->domains, i);
 407                 if (tpdomain->domain == domain)
 408                         return tpdomain;
 409         }
 410
 411         if (create) {
 412                 tpdomain = g_new0 (ThreadPoolDomain, 1);
 413                 tpdomain->domain = domain;
 414                 domain_add (tpdomain);
 415         }
 416
 417         return tpdomain;
 418 }
 419
 420 static void
 421 domain_free (ThreadPoolDomain *tpdomain)
 422 {
 423         g_free (tpdomain);
 424 }
 425
 426 /* LOCKING: threadpool->domains_lock must be held */
 427 static gboolean
 428 domain_any_has_request (void)
 429 {
 430         guint i;
 431
 432         for (i = 0; i < threadpool->domains->len; ++i) {
 433                 ThreadPoolDomain *tmp = g_ptr_array_index (threadpool->domains, i);
 434                 if (tmp->outstanding_request > 0)
 435                         return TRUE;
 436         }
 437
 438         return FALSE;
 439 }
 440
 441 /* LOCKING: threadpool->domains_lock must be held */
 442 static ThreadPoolDomain *
 443 domain_get_next (ThreadPoolDomain *current)
 444 {
 445         ThreadPoolDomain *tpdomain = NULL;
 446         guint len;
 447
 448         len = threadpool->domains->len;
 449         if (len > 0) {
 450                 guint i, current_idx = -1;
 451                 if (current) {
 452                         for (i = 0; i < len; ++i) {
 453                                 if (current == g_ptr_array_index (threadpool->domains, i)) {
 454                                         current_idx = i;
 455                                         break;
 456                                 }
 457                         }
 458                         g_assert (current_idx >= 0);
 459                 }
 460                 for (i = current_idx + 1; i < len + current_idx + 1; ++i) {
 461                         ThreadPoolDomain *tmp = g_ptr_array_index (threadpool->domains, i % len);
 462                         if (tmp->outstanding_request > 0) {
 463                                 tpdomain = tmp;
 464                                 break;
 465                         }
 466                 }
 467         }
 468
 469         return tpdomain;
 470 }
 471
 472 static void
 473 worker_wait_interrupt (gpointer data)
 474 {
 475         mono_coop_mutex_lock (&threadpool->active_threads_lock);
 476         mono_coop_cond_signal (&threadpool->parked_threads_cond);
 477         mono_coop_mutex_unlock (&threadpool->active_threads_lock);
 478 }
 479
 480 /* return TRUE if timeout, FALSE otherwise (worker unpark or interrupt) */
 481 static gboolean
 482 worker_park (void)
 483 {
 484         gboolean timeout = FALSE;
 485
 486         mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] current worker parking", mono_native_thread_id_get ());
 487
 488         mono_gc_set_skip_thread (TRUE);
 489
 490         mono_coop_mutex_lock (&threadpool->active_threads_lock);
 491
 492         if (!mono_runtime_is_shutting_down ()) {
 493                 static gpointer rand_handle = NULL;
 494                 MonoInternalThread *thread_internal;
 495                 gboolean interrupted = FALSE;
 496
 497                 if (!rand_handle)
 498                         rand_handle = rand_create ();
 499                 g_assert (rand_handle);
 500
 501                 thread_internal = mono_thread_internal_current ();
 502                 g_assert (thread_internal);
 503
 504                 threadpool->parked_threads_count += 1;
 505                 g_ptr_array_remove_fast (threadpool->working_threads, thread_internal);
 506
 507                 mono_thread_info_install_interrupt (worker_wait_interrupt, NULL, &interrupted);
 508                 if (interrupted)
 509                         goto done;
 510
 511                 if (mono_coop_cond_timedwait (&threadpool->parked_threads_cond, &threadpool->active_threads_lock, rand_next (rand_handle, 5 * 1000, 60 * 1000)) != 0)
 512                         timeout = TRUE;
 513
 514                 mono_thread_info_uninstall_interrupt (&interrupted);
 515
 516 done:
 517                 g_ptr_array_add (threadpool->working_threads, thread_internal);
 518                 threadpool->parked_threads_count -= 1;
 519         }
 520
 521         mono_coop_mutex_unlock (&threadpool->active_threads_lock);
 522
 523         mono_gc_set_skip_thread (FALSE);
 524
 525         mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] current worker unparking, timeout? %s", mono_native_thread_id_get (), timeout ? "yes" : "no");
 526
 527         return timeout;
 528 }
 529
 530 static gboolean
 531 worker_try_unpark (void)
 532 {
 533         gboolean res = FALSE;
 534
 535         mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] try unpark worker", mono_native_thread_id_get ());
 536
 537         mono_coop_mutex_lock (&threadpool->active_threads_lock);
 538         if (threadpool->parked_threads_count > 0) {
 539                 mono_coop_cond_signal (&threadpool->parked_threads_cond);
 540                 res = TRUE;
 541         }
 542         mono_coop_mutex_unlock (&threadpool->active_threads_lock);
 543
 544         mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] try unpark worker, success? %s", mono_native_thread_id_get (), res ? "yes" : "no");
 545
 546         return res;
 547 }
 548
 549 static void
 550 worker_kill (ThreadPoolWorkingThread *thread)
 551 {
 552         if (thread == mono_thread_internal_current ())
 553                 return;
 554
 555         mono_thread_internal_stop ((MonoInternalThread*) thread);
 556 }
 557
 558 static void
 559 worker_thread (gpointer data)
 560 {
 561         MonoInternalThread *thread;
 562         ThreadPoolDomain *tpdomain, *previous_tpdomain;
 563         ThreadPoolCounter counter;
 564         gboolean retire = FALSE;
 565
 566         mono_trace (G_LOG_LEVEL_INFO, MONO_TRACE_THREADPOOL, "[%p] worker starting", mono_native_thread_id_get ());
 567
 568         g_assert (threadpool);
 569
 570         thread = mono_thread_internal_current ();
 571         g_assert (thread);
 572
 573         mono_thread_set_name_internal (thread, mono_string_new (mono_domain_get (), "Threadpool worker"), FALSE);
 574
 575         mono_coop_mutex_lock (&threadpool->active_threads_lock);
 576         g_ptr_array_add (threadpool->working_threads, thread);
 577         mono_coop_mutex_unlock (&threadpool->active_threads_lock);
 578
 579         previous_tpdomain = NULL;
 580
 581         mono_coop_mutex_lock (&threadpool->domains_lock);
 582
 583         while (!mono_runtime_is_shutting_down ()) {
 584                 tpdomain = NULL;
 585
 586                 if ((thread->state & (ThreadState_StopRequested | ThreadState_SuspendRequested)) != 0) {
 587                         mono_coop_mutex_unlock (&threadpool->domains_lock);
 588                         mono_thread_interruption_checkpoint ();
 589                         mono_coop_mutex_lock (&threadpool->domains_lock);
 590                 }
 591
 592                 if (retire || !(tpdomain = domain_get_next (previous_tpdomain))) {
 593                         gboolean timeout;
 594
 595                         COUNTER_ATOMIC (counter, {
 596                                 counter._.working --;
 597                                 counter._.parked ++;
 598                         });
 599
 600                         mono_coop_mutex_unlock (&threadpool->domains_lock);
 601                         timeout = worker_park ();
 602                         mono_coop_mutex_lock (&threadpool->domains_lock);
 603
 604                         COUNTER_ATOMIC (counter, {
 605                                 counter._.working ++;
 606                                 counter._.parked --;
 607                         });
 608
 609                         if (timeout)
 610                                 break;
 611
 612                         if (retire)
 613                                 retire = FALSE;
 614
 615                         continue;
 616                 }
 617
 618                 tpdomain->outstanding_request --;
 619                 g_assert (tpdomain->outstanding_request >= 0);
 620
 621                 mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] worker running in domain %p",
 622                         mono_native_thread_id_get (), tpdomain->domain, tpdomain->outstanding_request);
 623
 624                 g_assert (tpdomain->domain);
 625                 g_assert (tpdomain->domain->threadpool_jobs >= 0);
 626                 tpdomain->domain->threadpool_jobs ++;
 627
 628                 mono_coop_mutex_unlock (&threadpool->domains_lock);
 629
 630                 mono_thread_push_appdomain_ref (tpdomain->domain);
 631                 if (mono_domain_set (tpdomain->domain, FALSE)) {
 632                         MonoObject *exc = NULL;
 633                         MonoObject *res = mono_runtime_invoke (mono_defaults.threadpool_perform_wait_callback_method, NULL, NULL, &exc);
 634                         if (exc)
 635                                 mono_thread_internal_unhandled_exception (exc);
 636                         else if (res && *(MonoBoolean*) mono_object_unbox (res) == FALSE)
 637                                 retire = TRUE;
 638
 639                         mono_thread_clr_state (thread , ~ThreadState_Background);
 640                         if (!mono_thread_test_state (thread , ThreadState_Background))
 641                                 ves_icall_System_Threading_Thread_SetState (thread, ThreadState_Background);
 642
 643                         mono_domain_set (mono_get_root_domain (), TRUE);
 644                 }
 645                 mono_thread_pop_appdomain_ref ();
 646
 647                 mono_coop_mutex_lock (&threadpool->domains_lock);
 648
 649                 tpdomain->domain->threadpool_jobs --;
 650                 g_assert (tpdomain->domain->threadpool_jobs >= 0);
 651
 652                 if (tpdomain->domain->threadpool_jobs == 0 && mono_domain_is_unloading (tpdomain->domain)) {
 653                         gboolean removed = domain_remove (tpdomain);
 654                         g_assert (removed);
 655                         if (tpdomain->domain->cleanup_semaphore)
 656                                 ReleaseSemaphore (tpdomain->domain->cleanup_semaphore, 1, NULL);
 657                         domain_free (tpdomain);
 658                         tpdomain = NULL;
 659                 }
 660
 661                 previous_tpdomain = tpdomain;
 662         }
 663
 664         mono_coop_mutex_unlock (&threadpool->domains_lock);
 665
 666         mono_coop_mutex_lock (&threadpool->active_threads_lock);
 667         g_ptr_array_remove_fast (threadpool->working_threads, thread);
 668         mono_coop_mutex_unlock (&threadpool->active_threads_lock);
 669
 670         COUNTER_ATOMIC (counter, {
 671                 counter._.working--;
 672                 counter._.active --;
 673         });
 674
 675         mono_trace (G_LOG_LEVEL_INFO, MONO_TRACE_THREADPOOL, "[%p] worker finishing", mono_native_thread_id_get ());
 676 }
 677
 678 static gboolean
 679 worker_try_create (void)
 680 {
 681         ThreadPoolCounter counter;
 682         MonoInternalThread *thread;
 683
 684         mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] try create worker", mono_native_thread_id_get ());
 685
 686         COUNTER_ATOMIC (counter, {
 687                 if (counter._.working >= counter._.max_working)
 688                         return FALSE;
 689                 counter._.working ++;
 690                 counter._.active ++;
 691         });
 692
 693         if ((thread = mono_thread_create_internal (mono_get_root_domain (), worker_thread, NULL, TRUE, 0)) != NULL) {
 694                 mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] try create worker, created %p",
 695                         mono_native_thread_id_get (), thread->tid);
 696                 return TRUE;
 697         }
 698
 699         mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] try create worker, failed", mono_native_thread_id_get ());
 700
 701         COUNTER_ATOMIC (counter, {
 702                 counter._.working --;
 703                 counter._.active --;
 704         });
 705
 706         return FALSE;
 707 }
 708
 709 static void monitor_ensure_running (void);
 710
 711 static gboolean
 712 worker_request (MonoDomain *domain)
 713 {
 714         ThreadPoolDomain *tpdomain;
 715
 716         g_assert (domain);
 717         g_assert (threadpool);
 718
 719         if (mono_runtime_is_shutting_down ())
 720                 return FALSE;
 721
 722         mono_coop_mutex_lock (&threadpool->domains_lock);
 723
 724         /* synchronize check with worker_thread */
 725         if (mono_domain_is_unloading (domain)) {
 726                 mono_coop_mutex_unlock (&threadpool->domains_lock);
 727                 return FALSE;
 728         }
 729
 730         tpdomain = domain_get (domain, TRUE);
 731         g_assert (tpdomain);
 732         tpdomain->outstanding_request ++;
 733
 734         mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] request worker, domain = %p, outstanding_request = %d",
 735                 mono_native_thread_id_get (), tpdomain->domain, tpdomain->outstanding_request);
 736
 737         mono_coop_mutex_unlock (&threadpool->domains_lock);
 738
 739         if (threadpool->suspended)
 740                 return FALSE;
 741
 742         monitor_ensure_running ();
 743
 744         if (worker_try_unpark ()) {
 745                 mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] request worker, unparked", mono_native_thread_id_get ());
 746                 return TRUE;
 747         }
 748
 749         if (worker_try_create ()) {
 750                 mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] request worker, created", mono_native_thread_id_get ());
 751                 return TRUE;
 752         }
 753
 754         mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] request worker, failed", mono_native_thread_id_get ());
 755         return FALSE;
 756 }
 757
 758 static gboolean
 759 monitor_should_keep_running (void)
 760 {
 761         static gint64 last_should_keep_running = -1;
 762
 763         g_assert (monitor_status == MONITOR_STATUS_WAITING_FOR_REQUEST || monitor_status == MONITOR_STATUS_REQUESTED);
 764
 765         if (InterlockedExchange (&monitor_status, MONITOR_STATUS_WAITING_FOR_REQUEST) == MONITOR_STATUS_WAITING_FOR_REQUEST) {
 766                 gboolean should_keep_running = TRUE, force_should_keep_running = FALSE;
 767
 768                 if (mono_runtime_is_shutting_down ()) {
 769                         should_keep_running = FALSE;
 770                 } else {
 771                         mono_coop_mutex_lock (&threadpool->domains_lock);
 772                         if (!domain_any_has_request ())
 773                                 should_keep_running = FALSE;
 774                         mono_coop_mutex_unlock (&threadpool->domains_lock);
 775
 776                         if (!should_keep_running) {
 777                                 if (last_should_keep_running == -1 || mono_100ns_ticks () - last_should_keep_running < MONITOR_MINIMAL_LIFETIME * 1000 * 10) {
 778                                         should_keep_running = force_should_keep_running = TRUE;
 779                                 }
 780                         }
 781                 }
 782
 783                 if (should_keep_running) {
 784                         if (last_should_keep_running == -1 || !force_should_keep_running)
 785                                 last_should_keep_running = mono_100ns_ticks ();
 786                 } else {
 787                         last_should_keep_running = -1;
 788                         if (InterlockedCompareExchange (&monitor_status, MONITOR_STATUS_NOT_RUNNING, MONITOR_STATUS_WAITING_FOR_REQUEST) == MONITOR_STATUS_WAITING_FOR_REQUEST)
 789                                 return FALSE;
 790                 }
 791         }
 792
 793         g_assert (monitor_status == MONITOR_STATUS_WAITING_FOR_REQUEST || monitor_status == MONITOR_STATUS_REQUESTED);
 794
 795         return TRUE;
 796 }
 797
 798 static gboolean
 799 monitor_sufficient_delay_since_last_dequeue (void)
 800 {
 801         guint32 threshold;
 802
 803         g_assert (threadpool);
 804
 805         if (threadpool->cpu_usage < CPU_USAGE_LOW) {
 806                 threshold = MONITOR_INTERVAL;
 807         } else {
 808                 ThreadPoolCounter counter;
 809                 counter.as_gint64 = COUNTER_READ();
 810                 threshold = counter._.max_working * MONITOR_INTERVAL * 2;
 811         }
 812
 813         return mono_msec_ticks () >= threadpool->heuristic_last_dequeue + threshold;
 814 }
 815
 816 static void hill_climbing_force_change (gint16 new_thread_count, ThreadPoolHeuristicStateTransition transition);
 817
 818 static void
 819 monitor_thread (void)
 820 {
 821         MonoInternalThread *current_thread = mono_thread_internal_current ();
 822         guint i;
 823
 824         mono_cpu_usage (threadpool->cpu_usage_state);
 825
 826         mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] monitor thread, started", mono_native_thread_id_get ());
 827
 828         do {
 829                 MonoInternalThread *thread;
 830                 gboolean all_waitsleepjoin = TRUE;
 831                 gint32 interval_left = MONITOR_INTERVAL;
 832                 gint32 awake = 0; /* number of spurious awakes we tolerate before doing a round of rebalancing */
 833
 834                 g_assert (monitor_status != MONITOR_STATUS_NOT_RUNNING);
 835
 836                 mono_gc_set_skip_thread (TRUE);
 837
 838                 do {
 839                         guint32 ts;
 840                         gboolean alerted = FALSE;
 841
 842                         if (mono_runtime_is_shutting_down ())
 843                                 break;
 844
 845                         ts = mono_msec_ticks ();
 846                         if (mono_thread_info_sleep (interval_left, &alerted) == 0)
 847                                 break;
 848                         interval_left -= mono_msec_ticks () - ts;
 849
 850                         mono_gc_set_skip_thread (FALSE);
 851                         if ((current_thread->state & (ThreadState_StopRequested | ThreadState_SuspendRequested)) != 0)
 852                                 mono_thread_interruption_checkpoint ();
 853                         mono_gc_set_skip_thread (TRUE);
 854                 } while (interval_left > 0 && ++awake < 10);
 855
 856                 mono_gc_set_skip_thread (FALSE);
 857
 858                 if (threadpool->suspended)
 859                         continue;
 860
 861                 if (mono_runtime_is_shutting_down ())
 862                         continue;
 863
 864                 mono_coop_mutex_lock (&threadpool->domains_lock);
 865                 if (!domain_any_has_request ()) {
 866                         mono_coop_mutex_unlock (&threadpool->domains_lock);
 867                         continue;
 868                 }
 869                 mono_coop_mutex_unlock (&threadpool->domains_lock);
 870
 871
 872                 mono_coop_mutex_lock (&threadpool->active_threads_lock);
 873                 for (i = 0; i < threadpool->working_threads->len; ++i) {
 874                         thread = g_ptr_array_index (threadpool->working_threads, i);
 875                         if ((thread->state & ThreadState_WaitSleepJoin) == 0) {
 876                                 all_waitsleepjoin = FALSE;
 877                                 break;
 878                         }
 879                 }
 880                 mono_coop_mutex_unlock (&threadpool->active_threads_lock);
 881
 882                 if (all_waitsleepjoin) {
 883                         ThreadPoolCounter counter;
 884                         COUNTER_ATOMIC (counter, { counter._.max_working ++; });
 885                         hill_climbing_force_change (counter._.max_working, TRANSITION_STARVATION);
 886                 }
 887
 888                 threadpool->cpu_usage = mono_cpu_usage (threadpool->cpu_usage_state);
 889
 890                 if (monitor_sufficient_delay_since_last_dequeue ()) {
 891                         for (i = 0; i < 5; ++i) {
 892                                 if (mono_runtime_is_shutting_down ())
 893                                         break;
 894
 895                                 if (worker_try_unpark ()) {
 896                                         mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] monitor thread, unparked", mono_native_thread_id_get ());
 897                                         break;
 898                                 }
 899
 900                                 if (worker_try_create ()) {
 901                                         mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] monitor thread, created", mono_native_thread_id_get ());
 902                                         break;
 903                                 }
 904                         }
 905                 }
 906         } while (monitor_should_keep_running ());
 907
 908         mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] monitor thread, finished", mono_native_thread_id_get ());
 909 }
 910
 911 static void
 912 monitor_ensure_running (void)
 913 {
 914         for (;;) {
 915                 switch (monitor_status) {
 916                 case MONITOR_STATUS_REQUESTED:
 917                         return;
 918                 case MONITOR_STATUS_WAITING_FOR_REQUEST:
 919                         InterlockedCompareExchange (&monitor_status, MONITOR_STATUS_REQUESTED, MONITOR_STATUS_WAITING_FOR_REQUEST);
 920                         break;
 921                 case MONITOR_STATUS_NOT_RUNNING:
 922                         if (mono_runtime_is_shutting_down ())
 923                                 return;
 924                         if (InterlockedCompareExchange (&monitor_status, MONITOR_STATUS_REQUESTED, MONITOR_STATUS_NOT_RUNNING) == MONITOR_STATUS_NOT_RUNNING) {
 925                                 if (!mono_thread_create_internal (mono_get_root_domain (), monitor_thread, NULL, TRUE, SMALL_STACK))
 926                                         monitor_status = MONITOR_STATUS_NOT_RUNNING;
 927                                 return;
 928                         }
 929                         break;
 930                 default: g_assert_not_reached ();
 931                 }
 932         }
 933 }
 934
 935 static void
 936 hill_climbing_change_thread_count (gint16 new_thread_count, ThreadPoolHeuristicStateTransition transition)
 937 {
 938         ThreadPoolHillClimbing *hc;
 939
 940         g_assert (threadpool);
 941
 942         hc = &threadpool->heuristic_hill_climbing;
 943
 944         mono_trace (G_LOG_LEVEL_INFO, MONO_TRACE_THREADPOOL, "[%p] hill climbing, change max number of threads %d", mono_native_thread_id_get (), new_thread_count);
 945
 946         hc->last_thread_count = new_thread_count;
 947         hc->current_sample_interval = rand_next (&hc->random_interval_generator, hc->sample_interval_low, hc->sample_interval_high);
 948         hc->elapsed_since_last_change = 0;
 949         hc->completions_since_last_change = 0;
 950 }
 951
 952 static void
 953 hill_climbing_force_change (gint16 new_thread_count, ThreadPoolHeuristicStateTransition transition)
 954 {
 955         ThreadPoolHillClimbing *hc;
 956
 957         g_assert (threadpool);
 958
 959         hc = &threadpool->heuristic_hill_climbing;
 960
 961         if (new_thread_count != hc->last_thread_count) {
 962                 hc->current_control_setting += new_thread_count - hc->last_thread_count;
 963                 hill_climbing_change_thread_count (new_thread_count, transition);
 964         }
 965 }
 966
 967 static double_complex
 968 hill_climbing_get_wave_component (gdouble *samples, guint sample_count, gdouble period)
 969 {
 970         ThreadPoolHillClimbing *hc;
 971         gdouble w, cosine, sine, coeff, q0, q1, q2;
 972         guint i;
 973
 974         g_assert (threadpool);
 975         g_assert (sample_count >= period);
 976         g_assert (period >= 2);
 977
 978         hc = &threadpool->heuristic_hill_climbing;
 979
 980         w = 2.0 * M_PI / period;
 981         cosine = cos (w);
 982         sine = sin (w);
 983         coeff = 2.0 * cosine;
 984         q0 = q1 = q2 = 0;
 985
 986         for (i = 0; i < sample_count; ++i) {
 987                 q0 = coeff * q1 - q2 + samples [(hc->total_samples - sample_count + i) % hc->samples_to_measure];
 988                 q2 = q1;
 989                 q1 = q0;
 990         }
 991
 992         return mono_double_complex_scalar_div (mono_double_complex_make (q1 - q2 * cosine, (q2 * sine)), ((gdouble)sample_count));
 993 }
 994
 995 static gint16
 996 hill_climbing_update (gint16 current_thread_count, guint32 sample_duration, gint32 completions, guint32 *adjustment_interval)
 997 {
 998         ThreadPoolHillClimbing *hc;
 999         ThreadPoolHeuristicStateTransition transition;
1000         gdouble throughput;
1001         gdouble throughput_error_estimate;
1002         gdouble confidence;
1003         gdouble move;
1004         gdouble gain;
1005         gint sample_index;
1006         gint sample_count;
1007         gint new_thread_wave_magnitude;
1008         gint new_thread_count;
1009         double_complex thread_wave_component;
1010         double_complex throughput_wave_component;
1011         double_complex ratio;
1012
1013         g_assert (threadpool);
1014         g_assert (adjustment_interval);
1015
1016         hc = &threadpool->heuristic_hill_climbing;
1017
1018         /* If someone changed the thread count without telling us, update our records accordingly. */
1019         if (current_thread_count != hc->last_thread_count)
1020                 hill_climbing_force_change (current_thread_count, TRANSITION_INITIALIZING);
1021
1022         /* Update the cumulative stats for this thread count */
1023         hc->elapsed_since_last_change += sample_duration;
1024         hc->completions_since_last_change += completions;
1025
1026         /* Add in any data we've already collected about this sample */
1027         sample_duration += hc->accumulated_sample_duration;
1028         completions += hc->accumulated_completion_count;
1029
1030         /* We need to make sure we're collecting reasonably accurate data. Since we're just counting the end
1031          * of each work item, we are goinng to be missing some data about what really happened during the
1032          * sample interval. The count produced by each thread includes an initial work item that may have
1033          * started well before the start of the interval, and each thread may have been running some new
1034          * work item for some time before the end of the interval, which did not yet get counted. So
1035          * our count is going to be off by +/- threadCount workitems.
1036          *
1037          * The exception is that the thread that reported to us last time definitely wasn't running any work
1038          * at that time, and the thread that's reporting now definitely isn't running a work item now. So
1039          * we really only need to consider threadCount-1 threads.
1040          *
1041          * Thus the percent error in our count is +/- (threadCount-1)/numCompletions.
1042          *
1043          * We cannot rely on the frequency-domain analysis we'll be doing later to filter out this error, because
1044          * of the way it accumulates over time. If this sample is off by, say, 33% in the negative direction,
1045          * then the next one likely will be too. The one after that will include the sum of the completions
1046          * we missed in the previous samples, and so will be 33% positive. So every three samples we'll have
1047          * two "low" samples and one "high" sample. This will appear as periodic variation right in the frequency
1048          * range we're targeting, which will not be filtered by the frequency-domain translation. */
1049         if (hc->total_samples > 0 && ((current_thread_count - 1.0) / completions) >= hc->max_sample_error) {
1050                 /* Not accurate enough yet. Let's accumulate the data so
1051                  * far, and tell the ThreadPool to collect a little more. */
1052                 hc->accumulated_sample_duration = sample_duration;
1053                 hc->accumulated_completion_count = completions;
1054                 *adjustment_interval = 10;
1055                 return current_thread_count;
1056         }
1057
1058         /* We've got enouugh data for our sample; reset our accumulators for next time. */
1059         hc->accumulated_sample_duration = 0;
1060         hc->accumulated_completion_count = 0;
1061
1062         /* Add the current thread count and throughput sample to our history. */
1063         throughput = ((gdouble) completions) / sample_duration;
1064
1065         sample_index = hc->total_samples % hc->samples_to_measure;
1066         hc->samples [sample_index] = throughput;
1067         hc->thread_counts [sample_index] = current_thread_count;
1068         hc->total_samples ++;
1069
1070         /* Set up defaults for our metrics. */
1071         thread_wave_component = mono_double_complex_make(0, 0);
1072         throughput_wave_component = mono_double_complex_make(0, 0);
1073         throughput_error_estimate = 0;
1074         ratio = mono_double_complex_make(0, 0);
1075         confidence = 0;
1076
1077         transition = TRANSITION_WARMUP;
1078
1079         /* How many samples will we use? It must be at least the three wave periods we're looking for, and it must also
1080          * be a whole multiple of the primary wave's period; otherwise the frequency we're looking for will fall between
1081          * two frequency bands in the Fourier analysis, and we won't be able to measure it accurately. */
1082         sample_count = ((gint) MIN (hc->total_samples - 1, hc->samples_to_measure) / hc->wave_period) * hc->wave_period;
1083
1084         if (sample_count > hc->wave_period) {
1085                 guint i;
1086                 gdouble average_throughput;
1087                 gdouble average_thread_count;
1088                 gdouble sample_sum = 0;
1089                 gdouble thread_sum = 0;
1090
1091                 /* Average the throughput and thread count samples, so we can scale the wave magnitudes later. */
1092                 for (i = 0; i < sample_count; ++i) {
1093                         guint j = (hc->total_samples - sample_count + i) % hc->samples_to_measure;
1094                         sample_sum += hc->samples [j];
1095                         thread_sum += hc->thread_counts [j];
1096                 }
1097
1098                 average_throughput = sample_sum / sample_count;
1099                 average_thread_count = thread_sum / sample_count;
1100
1101                 if (average_throughput > 0 && average_thread_count > 0) {
1102                         gdouble noise_for_confidence, adjacent_period_1, adjacent_period_2;
1103
1104                         /* Calculate the periods of the adjacent frequency bands we'll be using to
1105                          * measure noise levels. We want the two adjacent Fourier frequency bands. */
1106                         adjacent_period_1 = sample_count / (((gdouble) sample_count) / ((gdouble) hc->wave_period) + 1);
1107                         adjacent_period_2 = sample_count / (((gdouble) sample_count) / ((gdouble) hc->wave_period) - 1);
1108
1109                         /* Get the the three different frequency components of the throughput (scaled by average
1110                          * throughput). Our "error" estimate (the amount of noise that might be present in the
1111                          * frequency band we're really interested in) is the average of the adjacent bands. */
1112                         throughput_wave_component = mono_double_complex_scalar_div (hill_climbing_get_wave_component (hc->samples, sample_count, hc->wave_period), average_throughput);
1113                         throughput_error_estimate = cabs (mono_double_complex_scalar_div (hill_climbing_get_wave_component (hc->samples, sample_count, adjacent_period_1), average_throughput));
1114
1115                         if (adjacent_period_2 <= sample_count) {
1116                                 throughput_error_estimate = MAX (throughput_error_estimate, cabs (mono_double_complex_scalar_div (hill_climbing_get_wave_component (
1117                                         hc->samples, sample_count, adjacent_period_2), average_throughput)));
1118                         }
1119
1120                         /* Do the same for the thread counts, so we have something to compare to. We don't
1121                          * measure thread count noise, because there is none; these are exact measurements. */
1122                         thread_wave_component = mono_double_complex_scalar_div (hill_climbing_get_wave_component (hc->thread_counts, sample_count, hc->wave_period), average_thread_count);
1123
1124                         /* Update our moving average of the throughput noise. We'll use this
1125                          * later as feedback to determine the new size of the thread wave. */
1126                         if (hc->average_throughput_noise == 0) {
1127                                 hc->average_throughput_noise = throughput_error_estimate;
1128                         } else {
1129                                 hc->average_throughput_noise = (hc->throughput_error_smoothing_factor * throughput_error_estimate)
1130                                         + ((1.0 + hc->throughput_error_smoothing_factor) * hc->average_throughput_noise);
1131                         }
1132
1133                         if (cabs (thread_wave_component) > 0) {
1134                                 /* Adjust the throughput wave so it's centered around the target wave,
1135                                  * and then calculate the adjusted throughput/thread ratio. */
1136                                 ratio = mono_double_complex_div (mono_double_complex_sub (throughput_wave_component, mono_double_complex_scalar_mul(thread_wave_component, hc->target_throughput_ratio)), thread_wave_component);
1137                                 transition = TRANSITION_CLIMBING_MOVE;
1138                         } else {
1139                                 ratio = mono_double_complex_make (0, 0);
1140                                 transition = TRANSITION_STABILIZING;
1141                         }
1142
1143                         noise_for_confidence = MAX (hc->average_throughput_noise, throughput_error_estimate);
1144                         if (noise_for_confidence > 0) {
1145                                 confidence = cabs (thread_wave_component) / noise_for_confidence / hc->target_signal_to_noise_ratio;
1146                         } else {
1147                                 /* there is no noise! */
1148                                 confidence = 1.0;
1149                         }
1150                 }
1151         }
1152
1153         /* We use just the real part of the complex ratio we just calculated. If the throughput signal
1154          * is exactly in phase with the thread signal, this will be the same as taking the magnitude of
1155          * the complex move and moving that far up. If they're 180 degrees out of phase, we'll move
1156          * backward (because this indicates that our changes are having the opposite of the intended effect).
1157          * If they're 90 degrees out of phase, we won't move at all, because we can't tell wether we're
1158          * having a negative or positive effect on throughput. */
1159         move = creal (ratio);
1160         move = CLAMP (move, -1.0, 1.0);
1161
1162         /* Apply our confidence multiplier. */
1163         move *= CLAMP (confidence, -1.0, 1.0);
1164
1165         /* Now apply non-linear gain, such that values around zero are attenuated, while higher values
1166          * are enhanced. This allows us to move quickly if we're far away from the target, but more slowly
1167         * if we're getting close, giving us rapid ramp-up without wild oscillations around the target. */
1168         gain = hc->max_change_per_second * sample_duration;
1169         move = pow (fabs (move), hc->gain_exponent) * (move >= 0.0 ? 1 : -1) * gain;
1170         move = MIN (move, hc->max_change_per_sample);
1171
1172         /* If the result was positive, and CPU is > 95%, refuse the move. */
1173         if (move > 0.0 && threadpool->cpu_usage > CPU_USAGE_HIGH)
1174                 move = 0.0;
1175
1176         /* Apply the move to our control setting. */
1177         hc->current_control_setting += move;
1178
1179         /* Calculate the new thread wave magnitude, which is based on the moving average we've been keeping of the
1180          * throughput error.  This average starts at zero, so we'll start with a nice safe little wave at first. */
1181         new_thread_wave_magnitude = (gint)(0.5 + (hc->current_control_setting * hc->average_throughput_noise
1182                 * hc->target_signal_to_noise_ratio * hc->thread_magnitude_multiplier * 2.0));
1183         new_thread_wave_magnitude = CLAMP (new_thread_wave_magnitude, 1, hc->max_thread_wave_magnitude);
1184
1185         /* Make sure our control setting is within the ThreadPool's limits. */
1186         hc->current_control_setting = CLAMP (hc->current_control_setting, threadpool->limit_worker_min, threadpool->limit_worker_max - new_thread_wave_magnitude);
1187
1188         /* Calculate the new thread count (control setting + square wave). */
1189         new_thread_count = (gint)(hc->current_control_setting + new_thread_wave_magnitude * ((hc->total_samples / (hc->wave_period / 2)) % 2));
1190
1191         /* Make sure the new thread count doesn't exceed the ThreadPool's limits. */
1192         new_thread_count = CLAMP (new_thread_count, threadpool->limit_worker_min, threadpool->limit_worker_max);
1193
1194         if (new_thread_count != current_thread_count)
1195                 hill_climbing_change_thread_count (new_thread_count, transition);
1196
1197         if (creal (ratio) < 0.0 && new_thread_count == threadpool->limit_worker_min)
1198                 *adjustment_interval = (gint)(0.5 + hc->current_sample_interval * (10.0 * MAX (-1.0 * creal (ratio), 1.0)));
1199         else
1200                 *adjustment_interval = hc->current_sample_interval;
1201
1202         return new_thread_count;
1203 }
1204
1205 static void
1206 heuristic_notify_work_completed (void)
1207 {
1208         g_assert (threadpool);
1209
1210         InterlockedIncrement (&threadpool->heuristic_completions);
1211         threadpool->heuristic_last_dequeue = mono_msec_ticks ();
1212 }
1213
1214 static gboolean
1215 heuristic_should_adjust (void)
1216 {
1217         g_assert (threadpool);
1218
1219         if (threadpool->heuristic_last_dequeue > threadpool->heuristic_last_adjustment + threadpool->heuristic_adjustment_interval) {
1220                 ThreadPoolCounter counter;
1221                 counter.as_gint64 = COUNTER_READ();
1222                 if (counter._.working <= counter._.max_working)
1223                         return TRUE;
1224         }
1225
1226         return FALSE;
1227 }
1228
1229 static void
1230 heuristic_adjust (void)
1231 {
1232         g_assert (threadpool);
1233
1234         if (mono_coop_mutex_trylock (&threadpool->heuristic_lock) == 0) {
1235                 gint32 completions = InterlockedExchange (&threadpool->heuristic_completions, 0);
1236                 guint32 sample_end = mono_msec_ticks ();
1237                 guint32 sample_duration = sample_end - threadpool->heuristic_sample_start;
1238
1239                 if (sample_duration >= threadpool->heuristic_adjustment_interval / 2) {
1240                         ThreadPoolCounter counter;
1241                         gint16 new_thread_count;
1242
1243                         counter.as_gint64 = COUNTER_READ ();
1244                         new_thread_count = hill_climbing_update (counter._.max_working, sample_duration, completions, &threadpool->heuristic_adjustment_interval);
1245
1246                         COUNTER_ATOMIC (counter, { counter._.max_working = new_thread_count; });
1247
1248                         if (new_thread_count > counter._.max_working)
1249                                 worker_request (mono_domain_get ());
1250
1251                         threadpool->heuristic_sample_start = sample_end;
1252                         threadpool->heuristic_last_adjustment = mono_msec_ticks ();
1253                 }
1254
1255                 mono_coop_mutex_unlock (&threadpool->heuristic_lock);
1256         }
1257 }
1258
1259 void
1260 mono_threadpool_ms_cleanup (void)
1261 {
1262         #ifndef DISABLE_SOCKETS
1263                 mono_threadpool_ms_io_cleanup ();
1264         #endif
1265         mono_lazy_cleanup (&status, cleanup);
1266 }
1267
1268 MonoAsyncResult *
1269 mono_threadpool_ms_begin_invoke (MonoDomain *domain, MonoObject *target, MonoMethod *method, gpointer *params)
1270 {
1271         static MonoClass *async_call_klass = NULL;
1272         MonoMethodMessage *message;
1273         MonoAsyncResult *async_result;
1274         MonoAsyncCall *async_call;
1275         MonoDelegate *async_callback = NULL;
1276         MonoObject *state = NULL;
1277
1278         if (!async_call_klass)
1279                 async_call_klass = mono_class_from_name (mono_defaults.corlib, "System", "MonoAsyncCall");
1280         g_assert (async_call_klass);
1281
1282         mono_lazy_initialize (&status, initialize);
1283
1284         message = mono_method_call_message_new (method, params, mono_get_delegate_invoke (method->klass), (params != NULL) ? (&async_callback) : NULL, (params != NULL) ? (&state) : NULL);
1285
1286         async_call = (MonoAsyncCall*) mono_object_new (domain, async_call_klass);
1287         MONO_OBJECT_SETREF (async_call, msg, message);
1288         MONO_OBJECT_SETREF (async_call, state, state);
1289
1290         if (async_callback) {
1291                 MONO_OBJECT_SETREF (async_call, cb_method, mono_get_delegate_invoke (((MonoObject*) async_callback)->vtable->klass));
1292                 MONO_OBJECT_SETREF (async_call, cb_target, async_callback);
1293         }
1294
1295         async_result = mono_async_result_new (domain, NULL, async_call->state, NULL, (MonoObject*) async_call);
1296         MONO_OBJECT_SETREF (async_result, async_delegate, target);
1297
1298         mono_threadpool_ms_enqueue_work_item (domain, (MonoObject*) async_result);
1299
1300         return async_result;
1301 }
1302
1303 MonoObject *
1304 mono_threadpool_ms_end_invoke (MonoAsyncResult *ares, MonoArray **out_args, MonoObject **exc)
1305 {
1306         MonoAsyncCall *ac;
1307
1308         g_assert (exc);
1309         g_assert (out_args);
1310
1311         *exc = NULL;
1312         *out_args = NULL;
1313
1314         /* check if already finished */
1315         mono_monitor_enter ((MonoObject*) ares);
1316
1317         if (ares->endinvoke_called) {
1318                 *exc = (MonoObject*) mono_get_exception_invalid_operation (NULL);
1319                 mono_monitor_exit ((MonoObject*) ares);
1320                 return NULL;
1321         }
1322
1323         ares->endinvoke_called = 1;
1324
1325         /* wait until we are really finished */
1326         if (ares->completed) {
1327                 mono_monitor_exit ((MonoObject *) ares);
1328         } else {
1329                 gpointer wait_event;
1330                 if (ares->handle) {
1331                         wait_event = mono_wait_handle_get_handle ((MonoWaitHandle*) ares->handle);
1332                 } else {
1333                         wait_event = CreateEvent (NULL, TRUE, FALSE, NULL);
1334                         g_assert(wait_event);
1335                         MONO_OBJECT_SETREF (ares, handle, (MonoObject*) mono_wait_handle_new (mono_object_domain (ares), wait_event));
1336                 }
1337                 mono_monitor_exit ((MonoObject*) ares);
1338                 MONO_PREPARE_BLOCKING;
1339                 WaitForSingleObjectEx (wait_event, INFINITE, TRUE);
1340                 MONO_FINISH_BLOCKING;
1341         }
1342
1343         ac = (MonoAsyncCall*) ares->object_data;
1344         g_assert (ac);
1345
1346         *exc = ac->msg->exc; /* FIXME: GC add write barrier */
1347         *out_args = ac->out_args;
1348         return ac->res;
1349 }
1350
1351 gboolean
1352 mono_threadpool_ms_remove_domain_jobs (MonoDomain *domain, int timeout)
1353 {
1354         gboolean res = TRUE;
1355         guint32 start;
1356         gpointer sem;
1357
1358         g_assert (domain);
1359         g_assert (timeout >= -1);
1360
1361         g_assert (mono_domain_is_unloading (domain));
1362
1363         if (timeout != -1)
1364                 start = mono_msec_ticks ();
1365
1366 #ifndef DISABLE_SOCKETS
1367         mono_threadpool_ms_io_remove_domain_jobs (domain);
1368         if (timeout != -1) {
1369                 timeout -= mono_msec_ticks () - start;
1370                 if (timeout < 0)
1371                         return FALSE;
1372         }
1373 #endif
1374
1375         /*
1376          * There might be some threads out that could be about to execute stuff from the given domain.
1377          * We avoid that by setting up a semaphore to be pulsed by the thread that reaches zero.
1378          */
1379         sem = domain->cleanup_semaphore = CreateSemaphore (NULL, 0, 1, NULL);
1380
1381         /*
1382          * The memory barrier here is required to have global ordering between assigning to cleanup_semaphone
1383          * and reading threadpool_jobs. Otherwise this thread could read a stale version of threadpool_jobs
1384          * and wait forever.
1385          */
1386         mono_memory_write_barrier ();
1387
1388         while (domain->threadpool_jobs) {
1389                 MONO_PREPARE_BLOCKING;
1390                 WaitForSingleObject (sem, timeout);
1391                 MONO_FINISH_BLOCKING;
1392                 if (timeout != -1) {
1393                         timeout -= mono_msec_ticks () - start;
1394                         if (timeout <= 0) {
1395                                 res = FALSE;
1396                                 break;
1397                         }
1398                 }
1399         }
1400
1401         domain->cleanup_semaphore = NULL;
1402         CloseHandle (sem);
1403
1404         return res;
1405 }
1406
1407 void
1408 mono_threadpool_ms_suspend (void)
1409 {
1410         if (threadpool)
1411                 threadpool->suspended = TRUE;
1412 }
1413
1414 void
1415 mono_threadpool_ms_resume (void)
1416 {
1417         if (threadpool)
1418                 threadpool->suspended = FALSE;
1419 }
1420
1421 void
1422 ves_icall_System_Threading_ThreadPool_GetAvailableThreadsNative (gint32 *worker_threads, gint32 *completion_port_threads)
1423 {
1424         if (!worker_threads || !completion_port_threads)
1425                 return;
1426
1427         mono_lazy_initialize (&status, initialize);
1428
1429         *worker_threads = threadpool->limit_worker_max;
1430         *completion_port_threads = threadpool->limit_io_max;
1431 }
1432
1433 void
1434 ves_icall_System_Threading_ThreadPool_GetMinThreadsNative (gint32 *worker_threads, gint32 *completion_port_threads)
1435 {
1436         if (!worker_threads || !completion_port_threads)
1437                 return;
1438
1439         mono_lazy_initialize (&status, initialize);
1440
1441         *worker_threads = threadpool->limit_worker_min;
1442         *completion_port_threads = threadpool->limit_io_min;
1443 }
1444
1445 void
1446 ves_icall_System_Threading_ThreadPool_GetMaxThreadsNative (gint32 *worker_threads, gint32 *completion_port_threads)
1447 {
1448         if (!worker_threads || !completion_port_threads)
1449                 return;
1450
1451         mono_lazy_initialize (&status, initialize);
1452
1453         *worker_threads = threadpool->limit_worker_max;
1454         *completion_port_threads = threadpool->limit_io_max;
1455 }
1456
1457 MonoBoolean
1458 ves_icall_System_Threading_ThreadPool_SetMinThreadsNative (gint32 worker_threads, gint32 completion_port_threads)
1459 {
1460         mono_lazy_initialize (&status, initialize);
1461
1462         if (worker_threads <= 0 || worker_threads > threadpool->limit_worker_max)
1463                 return FALSE;
1464         if (completion_port_threads <= 0 || completion_port_threads > threadpool->limit_io_max)
1465                 return FALSE;
1466
1467         threadpool->limit_worker_max = worker_threads;
1468         threadpool->limit_io_max = completion_port_threads;
1469
1470         return TRUE;
1471 }
1472
1473 MonoBoolean
1474 ves_icall_System_Threading_ThreadPool_SetMaxThreadsNative (gint32 worker_threads, gint32 completion_port_threads)
1475 {
1476         gint cpu_count = mono_cpu_count ();
1477
1478         mono_lazy_initialize (&status, initialize);
1479
1480         if (worker_threads < threadpool->limit_worker_min || worker_threads < cpu_count)
1481                 return FALSE;
1482         if (completion_port_threads < threadpool->limit_io_min || completion_port_threads < cpu_count)
1483                 return FALSE;
1484
1485         threadpool->limit_worker_max = worker_threads;
1486         threadpool->limit_io_max = completion_port_threads;
1487
1488         return TRUE;
1489 }
1490
1491 void
1492 ves_icall_System_Threading_ThreadPool_InitializeVMTp (MonoBoolean *enable_worker_tracking)
1493 {
1494         if (enable_worker_tracking) {
1495                 // TODO implement some kind of switch to have the possibily to use it
1496                 *enable_worker_tracking = FALSE;
1497         }
1498
1499         mono_lazy_initialize (&status, initialize);
1500 }
1501
1502 MonoBoolean
1503 ves_icall_System_Threading_ThreadPool_NotifyWorkItemComplete (void)
1504 {
1505         ThreadPoolCounter counter;
1506
1507         if (mono_domain_is_unloading (mono_domain_get ()) || mono_runtime_is_shutting_down ())
1508                 return FALSE;
1509
1510         heuristic_notify_work_completed ();
1511
1512         if (heuristic_should_adjust ())
1513                 heuristic_adjust ();
1514
1515         counter.as_gint64 = COUNTER_READ ();
1516         return counter._.working <= counter._.max_working;
1517 }
1518
1519 void
1520 ves_icall_System_Threading_ThreadPool_NotifyWorkItemProgressNative (void)
1521 {
1522         heuristic_notify_work_completed ();
1523
1524         if (heuristic_should_adjust ())
1525                 heuristic_adjust ();
1526 }
1527
1528 void
1529 ves_icall_System_Threading_ThreadPool_ReportThreadStatus (MonoBoolean is_working)
1530 {
1531         // TODO
1532         mono_raise_exception (mono_get_exception_not_implemented (NULL));
1533 }
1534
1535 MonoBoolean
1536 ves_icall_System_Threading_ThreadPool_RequestWorkerThread (void)
1537 {
1538         return worker_request (mono_domain_get ());
1539 }
1540
1541 MonoBoolean G_GNUC_UNUSED
1542 ves_icall_System_Threading_ThreadPool_PostQueuedCompletionStatus (MonoNativeOverlapped *native_overlapped)
1543 {
1544         /* This copy the behavior of the current Mono implementation */
1545         mono_raise_exception (mono_get_exception_not_implemented (NULL));
1546         return FALSE;
1547 }
1548
1549 MonoBoolean G_GNUC_UNUSED
1550 ves_icall_System_Threading_ThreadPool_BindIOCompletionCallbackNative (gpointer file_handle)
1551 {
1552         /* This copy the behavior of the current Mono implementation */
1553         return TRUE;
1554 }
1555
1556 MonoBoolean G_GNUC_UNUSED
1557 ves_icall_System_Threading_ThreadPool_IsThreadPoolHosted (void)
1558 {
1559         return FALSE;
1560 }