mono/metadata/threadpool-worker-default.c

   1 /**
   2  * \file
   3  * native threadpool worker
   4  *
   5  * Author:
   6  *      Ludovic Henry (ludovic.henry@xamarin.com)
   7  *
   8  * Licensed under the MIT license. See LICENSE file in the project root for full license information.
   9  */
  10
  11 #include <stdlib.h>
  12 #define _USE_MATH_DEFINES // needed by MSVC to define math constants
  13 #include <math.h>
  14 #include <config.h>
  15 #include <glib.h>
  16
  17 #include <mono/metadata/class-internals.h>
  18 #include <mono/metadata/exception.h>
  19 #include <mono/metadata/gc-internals.h>
  20 #include <mono/metadata/object.h>
  21 #include <mono/metadata/object-internals.h>
  22 #include <mono/metadata/threadpool.h>
  23 #include <mono/metadata/threadpool-worker.h>
  24 #include <mono/metadata/threadpool-io.h>
  25 #include <mono/metadata/w32event.h>
  26 #include <mono/utils/atomic.h>
  27 #include <mono/utils/mono-compiler.h>
  28 #include <mono/utils/mono-complex.h>
  29 #include <mono/utils/mono-logger.h>
  30 #include <mono/utils/mono-logger-internals.h>
  31 #include <mono/utils/mono-proclib.h>
  32 #include <mono/utils/mono-threads.h>
  33 #include <mono/utils/mono-time.h>
  34 #include <mono/utils/mono-rand.h>
  35 #include <mono/utils/refcount.h>
  36 #include <mono/utils/w32api.h>
  37
  38 #define CPU_USAGE_LOW 80
  39 #define CPU_USAGE_HIGH 95
  40
  41 #define MONITOR_INTERVAL 500 // ms
  42 #define MONITOR_MINIMAL_LIFETIME 60 * 1000 // ms
  43
  44 #define WORKER_CREATION_MAX_PER_SEC 10
  45
  46 /* The exponent to apply to the gain. 1.0 means to use linear gain,
  47  * higher values will enhance large moves and damp small ones.
  48  * default: 2.0 */
  49 #define HILL_CLIMBING_GAIN_EXPONENT 2.0
  50
  51 /* The 'cost' of a thread. 0 means drive for increased throughput regardless
  52  * of thread count, higher values bias more against higher thread counts.
  53  * default: 0.15 */
  54 #define HILL_CLIMBING_BIAS 0.15
  55
  56 #define HILL_CLIMBING_WAVE_PERIOD 4
  57 #define HILL_CLIMBING_MAX_WAVE_MAGNITUDE 20
  58 #define HILL_CLIMBING_WAVE_MAGNITUDE_MULTIPLIER 1.0
  59 #define HILL_CLIMBING_WAVE_HISTORY_SIZE 8
  60 #define HILL_CLIMBING_TARGET_SIGNAL_TO_NOISE_RATIO 3.0
  61 #define HILL_CLIMBING_MAX_CHANGE_PER_SECOND 4
  62 #define HILL_CLIMBING_MAX_CHANGE_PER_SAMPLE 20
  63 #define HILL_CLIMBING_SAMPLE_INTERVAL_LOW 10
  64 #define HILL_CLIMBING_SAMPLE_INTERVAL_HIGH 200
  65 #define HILL_CLIMBING_ERROR_SMOOTHING_FACTOR 0.01
  66 #define HILL_CLIMBING_MAX_SAMPLE_ERROR_PERCENT 0.15
  67
  68 typedef enum {
  69         TRANSITION_WARMUP,
  70         TRANSITION_INITIALIZING,
  71         TRANSITION_RANDOM_MOVE,
  72         TRANSITION_CLIMBING_MOVE,
  73         TRANSITION_CHANGE_POINT,
  74         TRANSITION_STABILIZING,
  75         TRANSITION_STARVATION,
  76         TRANSITION_THREAD_TIMED_OUT,
  77         TRANSITION_UNDEFINED,
  78 } ThreadPoolHeuristicStateTransition;
  79
  80 typedef struct {
  81         gint32 wave_period;
  82         gint32 samples_to_measure;
  83         gdouble target_throughput_ratio;
  84         gdouble target_signal_to_noise_ratio;
  85         gdouble max_change_per_second;
  86         gdouble max_change_per_sample;
  87         gint32 max_thread_wave_magnitude;
  88         gint32 sample_interval_low;
  89         gdouble thread_magnitude_multiplier;
  90         gint32 sample_interval_high;
  91         gdouble throughput_error_smoothing_factor;
  92         gdouble gain_exponent;
  93         gdouble max_sample_error;
  94
  95         gdouble current_control_setting;
  96         gint64 total_samples;
  97         gint16 last_thread_count;
  98         gdouble elapsed_since_last_change;
  99         gdouble completions_since_last_change;
 100
 101         gdouble average_throughput_noise;
 102
 103         gdouble *samples;
 104         gdouble *thread_counts;
 105
 106         guint32 current_sample_interval;
 107         gpointer random_interval_generator;
 108
 109         gint32 accumulated_completion_count;
 110         gdouble accumulated_sample_duration;
 111 } ThreadPoolHillClimbing;
 112
 113 typedef struct {
 114         MonoThreadPoolWorkerCallback callback;
 115         gpointer data;
 116 } ThreadPoolWorkItem;
 117
 118 typedef union {
 119         struct {
 120                 gint16 max_working; /* determined by heuristic */
 121                 gint16 starting; /* starting, but not yet in worker_thread */
 122                 gint16 working; /* executing worker_thread */
 123                 gint16 parked; /* parked */
 124         } _;
 125         gint64 as_gint64;
 126 } ThreadPoolWorkerCounter;
 127
 128 typedef struct {
 129         MonoRefCount ref;
 130
 131         ThreadPoolWorkerCounter counters;
 132
 133         MonoCoopMutex parked_threads_lock;
 134         gint32 parked_threads_count;
 135         MonoCoopCond parked_threads_cond;
 136
 137         ThreadPoolWorkItem *work_items; // ThreadPoolWorkItem []
 138         gint32 work_items_count;
 139         gint32 work_items_size;
 140         MonoCoopMutex work_items_lock;
 141
 142         guint32 worker_creation_current_second;
 143         guint32 worker_creation_current_count;
 144         MonoCoopMutex worker_creation_lock;
 145
 146         gint32 heuristic_completions;
 147         gint64 heuristic_sample_start;
 148         gint64 heuristic_last_dequeue; // ms
 149         gint64 heuristic_last_adjustment; // ms
 150         gint64 heuristic_adjustment_interval; // ms
 151         ThreadPoolHillClimbing heuristic_hill_climbing;
 152         MonoCoopMutex heuristic_lock;
 153
 154         gint32 limit_worker_min;
 155         gint32 limit_worker_max;
 156
 157         MonoCpuUsageState *cpu_usage_state;
 158         gint32 cpu_usage;
 159
 160         /* suspended by the debugger */
 161         gboolean suspended;
 162
 163         gint32 monitor_status;
 164 } ThreadPoolWorker;
 165
 166 enum {
 167         MONITOR_STATUS_REQUESTED,
 168         MONITOR_STATUS_WAITING_FOR_REQUEST,
 169         MONITOR_STATUS_NOT_RUNNING,
 170 };
 171
 172 static ThreadPoolWorker worker;
 173
 174 #define COUNTER_CHECK(counter) \
 175         do { \
 176                 g_assert (counter._.max_working > 0); \
 177                 g_assert (counter._.starting >= 0); \
 178                 g_assert (counter._.working >= 0); \
 179         } while (0)
 180
 181 #define COUNTER_ATOMIC(var,block) \
 182         do { \
 183                 ThreadPoolWorkerCounter __old; \
 184                 do { \
 185                         __old = COUNTER_READ (); \
 186                         (var) = __old; \
 187                         { block; } \
 188                         COUNTER_CHECK (var); \
 189                 } while (InterlockedCompareExchange64 (&worker.counters.as_gint64, (var).as_gint64, __old.as_gint64) != __old.as_gint64); \
 190         } while (0)
 191
 192 static inline ThreadPoolWorkerCounter
 193 COUNTER_READ (void)
 194 {
 195         ThreadPoolWorkerCounter counter;
 196         counter.as_gint64 = InterlockedRead64 (&worker.counters.as_gint64);
 197         return counter;
 198 }
 199
 200 static gpointer
 201 rand_create (void)
 202 {
 203         mono_rand_open ();
 204         return mono_rand_init (NULL, 0);
 205 }
 206
 207 static guint32
 208 rand_next (gpointer *handle, guint32 min, guint32 max)
 209 {
 210         MonoError error;
 211         guint32 val;
 212         mono_rand_try_get_uint32 (handle, &val, min, max, &error);
 213         // FIXME handle error
 214         mono_error_assert_ok (&error);
 215         return val;
 216 }
 217
 218 static void
 219 destroy (gpointer data)
 220 {
 221         mono_coop_mutex_destroy (&worker.parked_threads_lock);
 222         mono_coop_cond_destroy (&worker.parked_threads_cond);
 223
 224         mono_coop_mutex_destroy (&worker.work_items_lock);
 225
 226         mono_coop_mutex_destroy (&worker.worker_creation_lock);
 227
 228         mono_coop_mutex_destroy (&worker.heuristic_lock);
 229
 230         g_free (worker.cpu_usage_state);
 231 }
 232
 233 void
 234 mono_threadpool_worker_init (void)
 235 {
 236         ThreadPoolHillClimbing *hc;
 237         const char *threads_per_cpu_env;
 238         gint threads_per_cpu;
 239         gint threads_count;
 240
 241         mono_refcount_init (&worker, destroy);
 242
 243         mono_coop_mutex_init (&worker.parked_threads_lock);
 244         worker.parked_threads_count = 0;
 245         mono_coop_cond_init (&worker.parked_threads_cond);
 246
 247         /* worker.work_items_size is inited to 0 */
 248         mono_coop_mutex_init (&worker.work_items_lock);
 249
 250         worker.worker_creation_current_second = -1;
 251         mono_coop_mutex_init (&worker.worker_creation_lock);
 252
 253         worker.heuristic_adjustment_interval = 10;
 254         mono_coop_mutex_init (&worker.heuristic_lock);
 255
 256         mono_rand_open ();
 257
 258         hc = &worker.heuristic_hill_climbing;
 259
 260         hc->wave_period = HILL_CLIMBING_WAVE_PERIOD;
 261         hc->max_thread_wave_magnitude = HILL_CLIMBING_MAX_WAVE_MAGNITUDE;
 262         hc->thread_magnitude_multiplier = (gdouble) HILL_CLIMBING_WAVE_MAGNITUDE_MULTIPLIER;
 263         hc->samples_to_measure = hc->wave_period * HILL_CLIMBING_WAVE_HISTORY_SIZE;
 264         hc->target_throughput_ratio = (gdouble) HILL_CLIMBING_BIAS;
 265         hc->target_signal_to_noise_ratio = (gdouble) HILL_CLIMBING_TARGET_SIGNAL_TO_NOISE_RATIO;
 266         hc->max_change_per_second = (gdouble) HILL_CLIMBING_MAX_CHANGE_PER_SECOND;
 267         hc->max_change_per_sample = (gdouble) HILL_CLIMBING_MAX_CHANGE_PER_SAMPLE;
 268         hc->sample_interval_low = HILL_CLIMBING_SAMPLE_INTERVAL_LOW;
 269         hc->sample_interval_high = HILL_CLIMBING_SAMPLE_INTERVAL_HIGH;
 270         hc->throughput_error_smoothing_factor = (gdouble) HILL_CLIMBING_ERROR_SMOOTHING_FACTOR;
 271         hc->gain_exponent = (gdouble) HILL_CLIMBING_GAIN_EXPONENT;
 272         hc->max_sample_error = (gdouble) HILL_CLIMBING_MAX_SAMPLE_ERROR_PERCENT;
 273         hc->current_control_setting = 0;
 274         hc->total_samples = 0;
 275         hc->last_thread_count = 0;
 276         hc->average_throughput_noise = 0;
 277         hc->elapsed_since_last_change = 0;
 278         hc->accumulated_completion_count = 0;
 279         hc->accumulated_sample_duration = 0;
 280         hc->samples = g_new0 (gdouble, hc->samples_to_measure);
 281         hc->thread_counts = g_new0 (gdouble, hc->samples_to_measure);
 282         hc->random_interval_generator = rand_create ();
 283         hc->current_sample_interval = rand_next (&hc->random_interval_generator, hc->sample_interval_low, hc->sample_interval_high);
 284
 285         if (!(threads_per_cpu_env = g_getenv ("MONO_THREADS_PER_CPU")))
 286                 threads_per_cpu = 1;
 287         else
 288                 threads_per_cpu = CLAMP (atoi (threads_per_cpu_env), 1, 50);
 289
 290         threads_count = mono_cpu_count () * threads_per_cpu;
 291
 292         worker.limit_worker_min = threads_count;
 293
 294 #if defined (PLATFORM_ANDROID) || defined (HOST_IOS)
 295         worker.limit_worker_max = CLAMP (threads_count * 100, MIN (threads_count, 200), MAX (threads_count, 200));
 296 #else
 297         worker.limit_worker_max = threads_count * 100;
 298 #endif
 299
 300         worker.counters._.max_working = worker.limit_worker_min;
 301
 302         worker.cpu_usage_state = g_new0 (MonoCpuUsageState, 1);
 303
 304         worker.suspended = FALSE;
 305
 306         worker.monitor_status = MONITOR_STATUS_NOT_RUNNING;
 307 }
 308
 309 void
 310 mono_threadpool_worker_cleanup (void)
 311 {
 312         mono_refcount_dec (&worker);
 313 }
 314
 315 static void
 316 work_item_lock (void)
 317 {
 318         mono_coop_mutex_lock (&worker.work_items_lock);
 319 }
 320
 321 static void
 322 work_item_unlock (void)
 323 {
 324         mono_coop_mutex_unlock (&worker.work_items_lock);
 325 }
 326
 327 static void
 328 work_item_push (MonoThreadPoolWorkerCallback callback, gpointer data)
 329 {
 330         ThreadPoolWorkItem work_item;
 331
 332         g_assert (callback);
 333
 334         work_item.callback = callback;
 335         work_item.data = data;
 336
 337         work_item_lock ();
 338
 339         g_assert (worker.work_items_count <= worker.work_items_size);
 340
 341         if (G_UNLIKELY (worker.work_items_count == worker.work_items_size)) {
 342                 worker.work_items_size += 64;
 343                 worker.work_items = g_renew (ThreadPoolWorkItem, worker.work_items, worker.work_items_size);
 344         }
 345
 346         g_assert (worker.work_items);
 347
 348         worker.work_items [worker.work_items_count ++] = work_item;
 349
 350         // printf ("[push] worker.work_items = %p, worker.work_items_count = %d, worker.work_items_size = %d\n",
 351         //      worker.work_items, worker.work_items_count, worker.work_items_size);
 352
 353         work_item_unlock ();
 354 }
 355
 356 static gboolean
 357 work_item_try_pop (ThreadPoolWorkItem *work_item)
 358 {
 359         g_assert (work_item);
 360
 361         work_item_lock ();
 362
 363         // printf ("[pop]  worker.work_items = %p, worker.work_items_count = %d, worker.work_items_size = %d\n",
 364         //      worker.work_items, worker.work_items_count, worker.work_items_size);
 365
 366         if (worker.work_items_count == 0) {
 367                 work_item_unlock ();
 368                 return FALSE;
 369         }
 370
 371         *work_item = worker.work_items [-- worker.work_items_count];
 372
 373         if (G_UNLIKELY (worker.work_items_count >= 64 * 3 && worker.work_items_count < worker.work_items_size / 2)) {
 374                 worker.work_items_size -= 64;
 375                 worker.work_items = g_renew (ThreadPoolWorkItem, worker.work_items, worker.work_items_size);
 376         }
 377
 378         work_item_unlock ();
 379
 380         return TRUE;
 381 }
 382
 383 static gint32
 384 work_item_count (void)
 385 {
 386         gint32 count;
 387
 388         work_item_lock ();
 389         count = worker.work_items_count;
 390         work_item_unlock ();
 391
 392         return count;
 393 }
 394
 395 static void worker_request (void);
 396
 397 void
 398 mono_threadpool_worker_enqueue (MonoThreadPoolWorkerCallback callback, gpointer data)
 399 {
 400         if (!mono_refcount_tryinc (&worker))
 401                 return;
 402
 403         work_item_push (callback, data);
 404
 405         worker_request ();
 406
 407         mono_refcount_dec (&worker);
 408 }
 409
 410 static void
 411 worker_wait_interrupt (gpointer unused)
 412 {
 413         /* If the runtime is not shutting down, we are not using this mechanism to wake up a unparked thread, and if the
 414          * runtime is shutting down, then we need to wake up ALL the threads.
 415          * It might be a bit wasteful, but I witnessed shutdown hang where the main thread would abort and then wait for all
 416          * background threads to exit (see mono_thread_manage). This would go wrong because not all threadpool threads would
 417          * be unparked. It would end up getting unstucked because of the timeout, but that would delay shutdown by 5-60s. */
 418         if (!mono_runtime_is_shutting_down ())
 419                 return;
 420
 421         if (!mono_refcount_tryinc (&worker))
 422                 return;
 423
 424         mono_coop_mutex_lock (&worker.parked_threads_lock);
 425         mono_coop_cond_broadcast (&worker.parked_threads_cond);
 426         mono_coop_mutex_unlock (&worker.parked_threads_lock);
 427
 428         mono_refcount_dec (&worker);
 429 }
 430
 431 /* return TRUE if timeout, FALSE otherwise (worker unpark or interrupt) */
 432 static gboolean
 433 worker_park (void)
 434 {
 435         gboolean timeout = FALSE;
 436         gboolean interrupted = FALSE;
 437
 438         mono_trace (G_LOG_LEVEL_INFO, MONO_TRACE_THREADPOOL, "[%p] worker parking", mono_native_thread_id_get ());
 439
 440         mono_coop_mutex_lock (&worker.parked_threads_lock);
 441
 442         if (!mono_runtime_is_shutting_down ()) {
 443                 static gpointer rand_handle = NULL;
 444                 MonoInternalThread *thread;
 445                 ThreadPoolWorkerCounter counter;
 446
 447                 if (!rand_handle)
 448                         rand_handle = rand_create ();
 449                 g_assert (rand_handle);
 450
 451                 thread = mono_thread_internal_current ();
 452                 g_assert (thread);
 453
 454                 COUNTER_ATOMIC (counter, {
 455                         counter._.working --;
 456                         counter._.parked ++;
 457                 });
 458
 459                 worker.parked_threads_count += 1;
 460
 461                 mono_thread_info_install_interrupt (worker_wait_interrupt, NULL, &interrupted);
 462                 if (interrupted)
 463                         goto done;
 464
 465                 if (mono_coop_cond_timedwait (&worker.parked_threads_cond, &worker.parked_threads_lock, rand_next (&rand_handle, 5 * 1000, 60 * 1000)) != 0)
 466                         timeout = TRUE;
 467
 468                 mono_thread_info_uninstall_interrupt (&interrupted);
 469
 470 done:
 471                 worker.parked_threads_count -= 1;
 472
 473                 COUNTER_ATOMIC (counter, {
 474                         counter._.working ++;
 475                         counter._.parked --;
 476                 });
 477         }
 478
 479         mono_coop_mutex_unlock (&worker.parked_threads_lock);
 480
 481         mono_trace (G_LOG_LEVEL_INFO, MONO_TRACE_THREADPOOL, "[%p] worker unparking, timeout? %s interrupted? %s",
 482                 mono_native_thread_id_get (), timeout ? "yes" : "no", interrupted ? "yes" : "no");
 483
 484         return timeout;
 485 }
 486
 487 static gboolean
 488 worker_try_unpark (void)
 489 {
 490         gboolean res = FALSE;
 491
 492         mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] try unpark worker", mono_native_thread_id_get ());
 493
 494         mono_coop_mutex_lock (&worker.parked_threads_lock);
 495         if (worker.parked_threads_count > 0) {
 496                 mono_coop_cond_signal (&worker.parked_threads_cond);
 497                 res = TRUE;
 498         }
 499         mono_coop_mutex_unlock (&worker.parked_threads_lock);
 500
 501         mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] try unpark worker, success? %s", mono_native_thread_id_get (), res ? "yes" : "no");
 502
 503         return res;
 504 }
 505
 506 static gsize WINAPI
 507 worker_thread (gpointer unused)
 508 {
 509         MonoInternalThread *thread;
 510         ThreadPoolWorkerCounter counter;
 511
 512         mono_trace (G_LOG_LEVEL_INFO, MONO_TRACE_THREADPOOL, "[%p] worker starting", mono_native_thread_id_get ());
 513
 514         if (!mono_refcount_tryinc (&worker))
 515                 return 0;
 516
 517         COUNTER_ATOMIC (counter, {
 518                 counter._.starting --;
 519                 counter._.working ++;
 520         });
 521
 522         thread = mono_thread_internal_current ();
 523         g_assert (thread);
 524
 525         while (!mono_runtime_is_shutting_down ()) {
 526                 ThreadPoolWorkItem work_item;
 527
 528                 if (mono_thread_interruption_checkpoint ())
 529                         continue;
 530
 531                 if (!work_item_try_pop (&work_item)) {
 532                         gboolean timeout;
 533
 534                         timeout = worker_park ();
 535                         if (timeout)
 536                                 break;
 537
 538                         continue;
 539                 }
 540
 541                 mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] worker executing %p (%p)",
 542                         mono_native_thread_id_get (), work_item.callback, work_item.data);
 543
 544                 work_item.callback (work_item.data);
 545         }
 546
 547         COUNTER_ATOMIC (counter, {
 548                 counter._.working --;
 549         });
 550
 551         mono_trace (G_LOG_LEVEL_INFO, MONO_TRACE_THREADPOOL, "[%p] worker finishing", mono_native_thread_id_get ());
 552
 553         mono_refcount_dec (&worker);
 554
 555         return 0;
 556 }
 557
 558 static gboolean
 559 worker_try_create (void)
 560 {
 561         MonoError error;
 562         MonoInternalThread *thread;
 563         gint64 current_ticks;
 564         gint32 now;
 565         ThreadPoolWorkerCounter counter;
 566
 567         if (mono_runtime_is_shutting_down ())
 568                 return FALSE;
 569
 570         mono_coop_mutex_lock (&worker.worker_creation_lock);
 571
 572         mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] try create worker", mono_native_thread_id_get ());
 573
 574         current_ticks = mono_100ns_ticks ();
 575         if (0 == current_ticks) {
 576                 g_warning ("failed to get 100ns ticks");
 577         } else {
 578                 now = current_ticks / (10 * 1000 * 1000);
 579                 if (worker.worker_creation_current_second != now) {
 580                         worker.worker_creation_current_second = now;
 581                         worker.worker_creation_current_count = 0;
 582                 } else {
 583                         g_assert (worker.worker_creation_current_count <= WORKER_CREATION_MAX_PER_SEC);
 584                         if (worker.worker_creation_current_count == WORKER_CREATION_MAX_PER_SEC) {
 585                                 mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] try create worker, failed: maximum number of worker created per second reached, current count = %d",
 586                                         mono_native_thread_id_get (), worker.worker_creation_current_count);
 587                                 mono_coop_mutex_unlock (&worker.worker_creation_lock);
 588                                 return FALSE;
 589                         }
 590                 }
 591         }
 592
 593         COUNTER_ATOMIC (counter, {
 594                 if (counter._.working >= counter._.max_working) {
 595                         mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] try create worker, failed: maximum number of working threads reached",
 596                                 mono_native_thread_id_get ());
 597                         mono_coop_mutex_unlock (&worker.worker_creation_lock);
 598                         return FALSE;
 599                 }
 600                 counter._.starting ++;
 601         });
 602
 603         thread = mono_thread_create_internal (mono_get_root_domain (), worker_thread, NULL, MONO_THREAD_CREATE_FLAGS_THREADPOOL, &error);
 604         if (!thread) {
 605                 mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] try create worker, failed: could not create thread due to %s", mono_native_thread_id_get (), mono_error_get_message (&error));
 606                 mono_error_cleanup (&error);
 607
 608                 COUNTER_ATOMIC (counter, {
 609                         counter._.starting --;
 610                 });
 611
 612                 mono_coop_mutex_unlock (&worker.worker_creation_lock);
 613
 614                 return FALSE;
 615         }
 616
 617         worker.worker_creation_current_count += 1;
 618
 619         mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] try create worker, created %p, now = %d count = %d",
 620                 mono_native_thread_id_get (), (gpointer) thread->tid, now, worker.worker_creation_current_count);
 621
 622         mono_coop_mutex_unlock (&worker.worker_creation_lock);
 623         return TRUE;
 624 }
 625
 626 static void monitor_ensure_running (void);
 627
 628 static void
 629 worker_request (void)
 630 {
 631         if (worker.suspended)
 632                 return;
 633
 634         monitor_ensure_running ();
 635
 636         if (worker_try_unpark ()) {
 637                 mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] request worker, unparked", mono_native_thread_id_get ());
 638                 return;
 639         }
 640
 641         if (worker_try_create ()) {
 642                 mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] request worker, created", mono_native_thread_id_get ());
 643                 return;
 644         }
 645
 646         mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] request worker, failed", mono_native_thread_id_get ());
 647 }
 648
 649 static gboolean
 650 monitor_should_keep_running (void)
 651 {
 652         static gint64 last_should_keep_running = -1;
 653
 654         g_assert (worker.monitor_status == MONITOR_STATUS_WAITING_FOR_REQUEST || worker.monitor_status == MONITOR_STATUS_REQUESTED);
 655
 656         if (InterlockedExchange (&worker.monitor_status, MONITOR_STATUS_WAITING_FOR_REQUEST) == MONITOR_STATUS_WAITING_FOR_REQUEST) {
 657                 gboolean should_keep_running = TRUE, force_should_keep_running = FALSE;
 658
 659                 if (mono_runtime_is_shutting_down ()) {
 660                         should_keep_running = FALSE;
 661                 } else {
 662                         if (work_item_count () == 0)
 663                                 should_keep_running = FALSE;
 664
 665                         if (!should_keep_running) {
 666                                 if (last_should_keep_running == -1 || mono_100ns_ticks () - last_should_keep_running < MONITOR_MINIMAL_LIFETIME * 1000 * 10) {
 667                                         should_keep_running = force_should_keep_running = TRUE;
 668                                 }
 669                         }
 670                 }
 671
 672                 if (should_keep_running) {
 673                         if (last_should_keep_running == -1 || !force_should_keep_running)
 674                                 last_should_keep_running = mono_100ns_ticks ();
 675                 } else {
 676                         last_should_keep_running = -1;
 677                         if (InterlockedCompareExchange (&worker.monitor_status, MONITOR_STATUS_NOT_RUNNING, MONITOR_STATUS_WAITING_FOR_REQUEST) == MONITOR_STATUS_WAITING_FOR_REQUEST)
 678                                 return FALSE;
 679                 }
 680         }
 681
 682         g_assert (worker.monitor_status == MONITOR_STATUS_WAITING_FOR_REQUEST || worker.monitor_status == MONITOR_STATUS_REQUESTED);
 683
 684         return TRUE;
 685 }
 686
 687 static gboolean
 688 monitor_sufficient_delay_since_last_dequeue (void)
 689 {
 690         gint64 threshold;
 691
 692         if (worker.cpu_usage < CPU_USAGE_LOW) {
 693                 threshold = MONITOR_INTERVAL;
 694         } else {
 695                 ThreadPoolWorkerCounter counter;
 696                 counter = COUNTER_READ ();
 697                 threshold = counter._.max_working * MONITOR_INTERVAL * 2;
 698         }
 699
 700         return mono_msec_ticks () >= worker.heuristic_last_dequeue + threshold;
 701 }
 702
 703 static void hill_climbing_force_change (gint16 new_thread_count, ThreadPoolHeuristicStateTransition transition);
 704
 705 static gsize WINAPI
 706 monitor_thread (gpointer unused)
 707 {
 708         MonoInternalThread *internal;
 709         guint i;
 710
 711         if (!mono_refcount_tryinc (&worker))
 712                 return 0;
 713
 714         internal = mono_thread_internal_current ();
 715         g_assert (internal);
 716
 717         mono_cpu_usage (worker.cpu_usage_state);
 718
 719         // printf ("monitor_thread: start\n");
 720
 721         mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] monitor thread, started", mono_native_thread_id_get ());
 722
 723         do {
 724                 ThreadPoolWorkerCounter counter;
 725                 gboolean limit_worker_max_reached;
 726                 gint32 interval_left = MONITOR_INTERVAL;
 727                 gint32 awake = 0; /* number of spurious awakes we tolerate before doing a round of rebalancing */
 728
 729                 g_assert (worker.monitor_status != MONITOR_STATUS_NOT_RUNNING);
 730
 731                 // counter = COUNTER_READ ();
 732                 // printf ("monitor_thread: starting = %d working = %d parked = %d max_working = %d\n",
 733                 //      counter._.starting, counter._.working, counter._.parked, counter._.max_working);
 734
 735                 do {
 736                         gint64 ts;
 737                         gboolean alerted = FALSE;
 738
 739                         if (mono_runtime_is_shutting_down ())
 740                                 break;
 741
 742                         ts = mono_msec_ticks ();
 743                         if (mono_thread_info_sleep (interval_left, &alerted) == 0)
 744                                 break;
 745                         interval_left -= mono_msec_ticks () - ts;
 746
 747                         mono_thread_interruption_checkpoint ();
 748                 } while (interval_left > 0 && ++awake < 10);
 749
 750                 if (mono_runtime_is_shutting_down ())
 751                         continue;
 752
 753                 if (worker.suspended)
 754                         continue;
 755
 756                 if (work_item_count () == 0)
 757                         continue;
 758
 759                 worker.cpu_usage = mono_cpu_usage (worker.cpu_usage_state);
 760
 761                 if (!monitor_sufficient_delay_since_last_dequeue ())
 762                         continue;
 763
 764                 limit_worker_max_reached = FALSE;
 765
 766                 COUNTER_ATOMIC (counter, {
 767                         if (counter._.max_working >= worker.limit_worker_max) {
 768                                 limit_worker_max_reached = TRUE;
 769                                 break;
 770                         }
 771                         counter._.max_working ++;
 772                 });
 773
 774                 if (limit_worker_max_reached)
 775                         continue;
 776
 777                 hill_climbing_force_change (counter._.max_working, TRANSITION_STARVATION);
 778
 779                 for (i = 0; i < 5; ++i) {
 780                         if (mono_runtime_is_shutting_down ())
 781                                 break;
 782
 783                         if (worker_try_unpark ()) {
 784                                 mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] monitor thread, unparked", mono_native_thread_id_get ());
 785                                 break;
 786                         }
 787
 788                         if (worker_try_create ()) {
 789                                 mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] monitor thread, created", mono_native_thread_id_get ());
 790                                 break;
 791                         }
 792                 }
 793         } while (monitor_should_keep_running ());
 794
 795         // printf ("monitor_thread: stop\n");
 796
 797         mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] monitor thread, finished", mono_native_thread_id_get ());
 798
 799         mono_refcount_dec (&worker);
 800         return 0;
 801 }
 802
 803 static void
 804 monitor_ensure_running (void)
 805 {
 806         MonoError error;
 807         for (;;) {
 808                 switch (worker.monitor_status) {
 809                 case MONITOR_STATUS_REQUESTED:
 810                         // printf ("monitor_thread: requested\n");
 811                         return;
 812                 case MONITOR_STATUS_WAITING_FOR_REQUEST:
 813                         // printf ("monitor_thread: waiting for request\n");
 814                         InterlockedCompareExchange (&worker.monitor_status, MONITOR_STATUS_REQUESTED, MONITOR_STATUS_WAITING_FOR_REQUEST);
 815                         break;
 816                 case MONITOR_STATUS_NOT_RUNNING:
 817                         // printf ("monitor_thread: not running\n");
 818                         if (mono_runtime_is_shutting_down ())
 819                                 return;
 820                         if (InterlockedCompareExchange (&worker.monitor_status, MONITOR_STATUS_REQUESTED, MONITOR_STATUS_NOT_RUNNING) == MONITOR_STATUS_NOT_RUNNING) {
 821                                 // printf ("monitor_thread: creating\n");
 822                                 if (!mono_thread_create_internal (mono_get_root_domain (), monitor_thread, NULL, MONO_THREAD_CREATE_FLAGS_THREADPOOL | MONO_THREAD_CREATE_FLAGS_SMALL_STACK, &error)) {
 823                                         // printf ("monitor_thread: creating failed\n");
 824                                         worker.monitor_status = MONITOR_STATUS_NOT_RUNNING;
 825                                         mono_error_cleanup (&error);
 826                                         mono_refcount_dec (&worker);
 827                                 }
 828                                 return;
 829                         }
 830                         break;
 831                 default: g_assert_not_reached ();
 832                 }
 833         }
 834 }
 835
 836 static void
 837 hill_climbing_change_thread_count (gint16 new_thread_count, ThreadPoolHeuristicStateTransition transition)
 838 {
 839         ThreadPoolHillClimbing *hc;
 840
 841         hc = &worker.heuristic_hill_climbing;
 842
 843         mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] hill climbing, change max number of threads %d", mono_native_thread_id_get (), new_thread_count);
 844
 845         hc->last_thread_count = new_thread_count;
 846         hc->current_sample_interval = rand_next (&hc->random_interval_generator, hc->sample_interval_low, hc->sample_interval_high);
 847         hc->elapsed_since_last_change = 0;
 848         hc->completions_since_last_change = 0;
 849 }
 850
 851 static void
 852 hill_climbing_force_change (gint16 new_thread_count, ThreadPoolHeuristicStateTransition transition)
 853 {
 854         ThreadPoolHillClimbing *hc;
 855
 856         hc = &worker.heuristic_hill_climbing;
 857
 858         if (new_thread_count != hc->last_thread_count) {
 859                 hc->current_control_setting += new_thread_count - hc->last_thread_count;
 860                 hill_climbing_change_thread_count (new_thread_count, transition);
 861         }
 862 }
 863
 864 static double_complex
 865 hill_climbing_get_wave_component (gdouble *samples, guint sample_count, gdouble period)
 866 {
 867         ThreadPoolHillClimbing *hc;
 868         gdouble w, cosine, sine, coeff, q0, q1, q2;
 869         guint i;
 870
 871         g_assert (sample_count >= period);
 872         g_assert (period >= 2);
 873
 874         hc = &worker.heuristic_hill_climbing;
 875
 876         w = 2.0 * M_PI / period;
 877         cosine = cos (w);
 878         sine = sin (w);
 879         coeff = 2.0 * cosine;
 880         q0 = q1 = q2 = 0;
 881
 882         for (i = 0; i < sample_count; ++i) {
 883                 q0 = coeff * q1 - q2 + samples [(hc->total_samples - sample_count + i) % hc->samples_to_measure];
 884                 q2 = q1;
 885                 q1 = q0;
 886         }
 887
 888         return mono_double_complex_scalar_div (mono_double_complex_make (q1 - q2 * cosine, (q2 * sine)), ((gdouble)sample_count));
 889 }
 890
 891 static gint16
 892 hill_climbing_update (gint16 current_thread_count, guint32 sample_duration, gint32 completions, gint64 *adjustment_interval)
 893 {
 894         ThreadPoolHillClimbing *hc;
 895         ThreadPoolHeuristicStateTransition transition;
 896         gdouble throughput;
 897         gdouble throughput_error_estimate;
 898         gdouble confidence;
 899         gdouble move;
 900         gdouble gain;
 901         gint sample_index;
 902         gint sample_count;
 903         gint new_thread_wave_magnitude;
 904         gint new_thread_count;
 905         double_complex thread_wave_component;
 906         double_complex throughput_wave_component;
 907         double_complex ratio;
 908
 909         g_assert (adjustment_interval);
 910
 911         hc = &worker.heuristic_hill_climbing;
 912
 913         /* If someone changed the thread count without telling us, update our records accordingly. */
 914         if (current_thread_count != hc->last_thread_count)
 915                 hill_climbing_force_change (current_thread_count, TRANSITION_INITIALIZING);
 916
 917         /* Update the cumulative stats for this thread count */
 918         hc->elapsed_since_last_change += sample_duration;
 919         hc->completions_since_last_change += completions;
 920
 921         /* Add in any data we've already collected about this sample */
 922         sample_duration += hc->accumulated_sample_duration;
 923         completions += hc->accumulated_completion_count;
 924
 925         /* We need to make sure we're collecting reasonably accurate data. Since we're just counting the end
 926          * of each work item, we are goinng to be missing some data about what really happened during the
 927          * sample interval. The count produced by each thread includes an initial work item that may have
 928          * started well before the start of the interval, and each thread may have been running some new
 929          * work item for some time before the end of the interval, which did not yet get counted. So
 930          * our count is going to be off by +/- threadCount workitems.
 931          *
 932          * The exception is that the thread that reported to us last time definitely wasn't running any work
 933          * at that time, and the thread that's reporting now definitely isn't running a work item now. So
 934          * we really only need to consider threadCount-1 threads.
 935          *
 936          * Thus the percent error in our count is +/- (threadCount-1)/numCompletions.
 937          *
 938          * We cannot rely on the frequency-domain analysis we'll be doing later to filter out this error, because
 939          * of the way it accumulates over time. If this sample is off by, say, 33% in the negative direction,
 940          * then the next one likely will be too. The one after that will include the sum of the completions
 941          * we missed in the previous samples, and so will be 33% positive. So every three samples we'll have
 942          * two "low" samples and one "high" sample. This will appear as periodic variation right in the frequency
 943          * range we're targeting, which will not be filtered by the frequency-domain translation. */
 944         if (hc->total_samples > 0 && ((current_thread_count - 1.0) / completions) >= hc->max_sample_error) {
 945                 /* Not accurate enough yet. Let's accumulate the data so
 946                  * far, and tell the ThreadPoolWorker to collect a little more. */
 947                 hc->accumulated_sample_duration = sample_duration;
 948                 hc->accumulated_completion_count = completions;
 949                 *adjustment_interval = 10;
 950                 return current_thread_count;
 951         }
 952
 953         /* We've got enouugh data for our sample; reset our accumulators for next time. */
 954         hc->accumulated_sample_duration = 0;
 955         hc->accumulated_completion_count = 0;
 956
 957         /* Add the current thread count and throughput sample to our history. */
 958         throughput = ((gdouble) completions) / sample_duration;
 959
 960         sample_index = hc->total_samples % hc->samples_to_measure;
 961         hc->samples [sample_index] = throughput;
 962         hc->thread_counts [sample_index] = current_thread_count;
 963         hc->total_samples ++;
 964
 965         /* Set up defaults for our metrics. */
 966         thread_wave_component = mono_double_complex_make(0, 0);
 967         throughput_wave_component = mono_double_complex_make(0, 0);
 968         throughput_error_estimate = 0;
 969         ratio = mono_double_complex_make(0, 0);
 970         confidence = 0;
 971
 972         transition = TRANSITION_WARMUP;
 973
 974         /* How many samples will we use? It must be at least the three wave periods we're looking for, and it must also
 975          * be a whole multiple of the primary wave's period; otherwise the frequency we're looking for will fall between
 976          * two frequency bands in the Fourier analysis, and we won't be able to measure it accurately. */
 977         sample_count = ((gint) MIN (hc->total_samples - 1, hc->samples_to_measure) / hc->wave_period) * hc->wave_period;
 978
 979         if (sample_count > hc->wave_period) {
 980                 guint i;
 981                 gdouble average_throughput;
 982                 gdouble average_thread_count;
 983                 gdouble sample_sum = 0;
 984                 gdouble thread_sum = 0;
 985
 986                 /* Average the throughput and thread count samples, so we can scale the wave magnitudes later. */
 987                 for (i = 0; i < sample_count; ++i) {
 988                         guint j = (hc->total_samples - sample_count + i) % hc->samples_to_measure;
 989                         sample_sum += hc->samples [j];
 990                         thread_sum += hc->thread_counts [j];
 991                 }
 992
 993                 average_throughput = sample_sum / sample_count;
 994                 average_thread_count = thread_sum / sample_count;
 995
 996                 if (average_throughput > 0 && average_thread_count > 0) {
 997                         gdouble noise_for_confidence, adjacent_period_1, adjacent_period_2;
 998
 999                         /* Calculate the periods of the adjacent frequency bands we'll be using to
1000                          * measure noise levels. We want the two adjacent Fourier frequency bands. */
1001                         adjacent_period_1 = sample_count / (((gdouble) sample_count) / ((gdouble) hc->wave_period) + 1);
1002                         adjacent_period_2 = sample_count / (((gdouble) sample_count) / ((gdouble) hc->wave_period) - 1);
1003
1004                         /* Get the the three different frequency components of the throughput (scaled by average
1005                          * throughput). Our "error" estimate (the amount of noise that might be present in the
1006                          * frequency band we're really interested in) is the average of the adjacent bands. */
1007                         throughput_wave_component = mono_double_complex_scalar_div (hill_climbing_get_wave_component (hc->samples, sample_count, hc->wave_period), average_throughput);
1008                         throughput_error_estimate = cabs (mono_double_complex_scalar_div (hill_climbing_get_wave_component (hc->samples, sample_count, adjacent_period_1), average_throughput));
1009
1010                         if (adjacent_period_2 <= sample_count) {
1011                                 throughput_error_estimate = MAX (throughput_error_estimate, cabs (mono_double_complex_scalar_div (hill_climbing_get_wave_component (
1012                                         hc->samples, sample_count, adjacent_period_2), average_throughput)));
1013                         }
1014
1015                         /* Do the same for the thread counts, so we have something to compare to. We don't
1016                          * measure thread count noise, because there is none; these are exact measurements. */
1017                         thread_wave_component = mono_double_complex_scalar_div (hill_climbing_get_wave_component (hc->thread_counts, sample_count, hc->wave_period), average_thread_count);
1018
1019                         /* Update our moving average of the throughput noise. We'll use this
1020                          * later as feedback to determine the new size of the thread wave. */
1021                         if (hc->average_throughput_noise == 0) {
1022                                 hc->average_throughput_noise = throughput_error_estimate;
1023                         } else {
1024                                 hc->average_throughput_noise = (hc->throughput_error_smoothing_factor * throughput_error_estimate)
1025                                         + ((1.0 + hc->throughput_error_smoothing_factor) * hc->average_throughput_noise);
1026                         }
1027
1028                         if (cabs (thread_wave_component) > 0) {
1029                                 /* Adjust the throughput wave so it's centered around the target wave,
1030                                  * and then calculate the adjusted throughput/thread ratio. */
1031                                 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);
1032                                 transition = TRANSITION_CLIMBING_MOVE;
1033                         } else {
1034                                 ratio = mono_double_complex_make (0, 0);
1035                                 transition = TRANSITION_STABILIZING;
1036                         }
1037
1038                         noise_for_confidence = MAX (hc->average_throughput_noise, throughput_error_estimate);
1039                         if (noise_for_confidence > 0) {
1040                                 confidence = cabs (thread_wave_component) / noise_for_confidence / hc->target_signal_to_noise_ratio;
1041                         } else {
1042                                 /* there is no noise! */
1043                                 confidence = 1.0;
1044                         }
1045                 }
1046         }
1047
1048         /* We use just the real part of the complex ratio we just calculated. If the throughput signal
1049          * is exactly in phase with the thread signal, this will be the same as taking the magnitude of
1050          * the complex move and moving that far up. If they're 180 degrees out of phase, we'll move
1051          * backward (because this indicates that our changes are having the opposite of the intended effect).
1052          * If they're 90 degrees out of phase, we won't move at all, because we can't tell wether we're
1053          * having a negative or positive effect on throughput. */
1054         move = creal (ratio);
1055         move = CLAMP (move, -1.0, 1.0);
1056
1057         /* Apply our confidence multiplier. */
1058         move *= CLAMP (confidence, -1.0, 1.0);
1059
1060         /* Now apply non-linear gain, such that values around zero are attenuated, while higher values
1061          * are enhanced. This allows us to move quickly if we're far away from the target, but more slowly
1062         * if we're getting close, giving us rapid ramp-up without wild oscillations around the target. */
1063         gain = hc->max_change_per_second * sample_duration;
1064         move = pow (fabs (move), hc->gain_exponent) * (move >= 0.0 ? 1 : -1) * gain;
1065         move = MIN (move, hc->max_change_per_sample);
1066
1067         /* If the result was positive, and CPU is > 95%, refuse the move. */
1068         if (move > 0.0 && worker.cpu_usage > CPU_USAGE_HIGH)
1069                 move = 0.0;
1070
1071         /* Apply the move to our control setting. */
1072         hc->current_control_setting += move;
1073
1074         /* Calculate the new thread wave magnitude, which is based on the moving average we've been keeping of the
1075          * throughput error.  This average starts at zero, so we'll start with a nice safe little wave at first. */
1076         new_thread_wave_magnitude = (gint)(0.5 + (hc->current_control_setting * hc->average_throughput_noise
1077                 * hc->target_signal_to_noise_ratio * hc->thread_magnitude_multiplier * 2.0));
1078         new_thread_wave_magnitude = CLAMP (new_thread_wave_magnitude, 1, hc->max_thread_wave_magnitude);
1079
1080         /* Make sure our control setting is within the ThreadPoolWorker's limits. */
1081         hc->current_control_setting = CLAMP (hc->current_control_setting, worker.limit_worker_min, worker.limit_worker_max - new_thread_wave_magnitude);
1082
1083         /* Calculate the new thread count (control setting + square wave). */
1084         new_thread_count = (gint)(hc->current_control_setting + new_thread_wave_magnitude * ((hc->total_samples / (hc->wave_period / 2)) % 2));
1085
1086         /* Make sure the new thread count doesn't exceed the ThreadPoolWorker's limits. */
1087         new_thread_count = CLAMP (new_thread_count, worker.limit_worker_min, worker.limit_worker_max);
1088
1089         if (new_thread_count != current_thread_count)
1090                 hill_climbing_change_thread_count (new_thread_count, transition);
1091
1092         if (creal (ratio) < 0.0 && new_thread_count == worker.limit_worker_min)
1093                 *adjustment_interval = (gint)(0.5 + hc->current_sample_interval * (10.0 * MAX (-1.0 * creal (ratio), 1.0)));
1094         else
1095                 *adjustment_interval = hc->current_sample_interval;
1096
1097         return new_thread_count;
1098 }
1099
1100 static gboolean
1101 heuristic_should_adjust (void)
1102 {
1103         if (worker.heuristic_last_dequeue > worker.heuristic_last_adjustment + worker.heuristic_adjustment_interval) {
1104                 ThreadPoolWorkerCounter counter;
1105                 counter = COUNTER_READ ();
1106                 if (counter._.working <= counter._.max_working)
1107                         return TRUE;
1108         }
1109
1110         return FALSE;
1111 }
1112
1113 static void
1114 heuristic_adjust (void)
1115 {
1116         if (mono_coop_mutex_trylock (&worker.heuristic_lock) == 0) {
1117                 gint32 completions = InterlockedExchange (&worker.heuristic_completions, 0);
1118                 gint64 sample_end = mono_msec_ticks ();
1119                 gint64 sample_duration = sample_end - worker.heuristic_sample_start;
1120
1121                 if (sample_duration >= worker.heuristic_adjustment_interval / 2) {
1122                         ThreadPoolWorkerCounter counter;
1123                         gint16 new_thread_count;
1124
1125                         counter = COUNTER_READ ();
1126                         new_thread_count = hill_climbing_update (counter._.max_working, sample_duration, completions, &worker.heuristic_adjustment_interval);
1127
1128                         COUNTER_ATOMIC (counter, {
1129                                 counter._.max_working = new_thread_count;
1130                         });
1131
1132                         if (new_thread_count > counter._.max_working)
1133                                 worker_request ();
1134
1135                         worker.heuristic_sample_start = sample_end;
1136                         worker.heuristic_last_adjustment = mono_msec_ticks ();
1137                 }
1138
1139                 mono_coop_mutex_unlock (&worker.heuristic_lock);
1140         }
1141 }
1142
1143 static void
1144 heuristic_notify_work_completed (void)
1145 {
1146         InterlockedIncrement (&worker.heuristic_completions);
1147         worker.heuristic_last_dequeue = mono_msec_ticks ();
1148
1149         if (heuristic_should_adjust ())
1150                 heuristic_adjust ();
1151 }
1152
1153 gboolean
1154 mono_threadpool_worker_notify_completed (void)
1155 {
1156         ThreadPoolWorkerCounter counter;
1157
1158         heuristic_notify_work_completed ();
1159
1160         counter = COUNTER_READ ();
1161         return counter._.working <= counter._.max_working;
1162 }
1163
1164 gint32
1165 mono_threadpool_worker_get_min (void)
1166 {
1167         gint32 ret;
1168
1169         if (!mono_refcount_tryinc (&worker))
1170                 return 0;
1171
1172         ret = worker.limit_worker_min;
1173
1174         mono_refcount_dec (&worker);
1175         return ret;
1176 }
1177
1178 gboolean
1179 mono_threadpool_worker_set_min (gint32 value)
1180 {
1181         if (value <= 0 || value > worker.limit_worker_max)
1182                 return FALSE;
1183
1184         if (!mono_refcount_tryinc (&worker))
1185                 return FALSE;
1186
1187         worker.limit_worker_min = value;
1188
1189         mono_refcount_dec (&worker);
1190         return TRUE;
1191 }
1192
1193 gint32
1194 mono_threadpool_worker_get_max (void)
1195 {
1196         gint32 ret;
1197
1198         if (!mono_refcount_tryinc (&worker))
1199                 return 0;
1200
1201         ret = worker.limit_worker_max;
1202
1203         mono_refcount_dec (&worker);
1204         return ret;
1205 }
1206
1207 gboolean
1208 mono_threadpool_worker_set_max (gint32 value)
1209 {
1210         gint32 cpu_count;
1211
1212         cpu_count = mono_cpu_count ();
1213         if (value < worker.limit_worker_min || value < cpu_count)
1214                 return FALSE;
1215
1216         if (!mono_refcount_tryinc (&worker))
1217                 return FALSE;
1218
1219         worker.limit_worker_max = value;
1220
1221         mono_refcount_dec (&worker);
1222         return TRUE;
1223 }
1224
1225 void
1226 mono_threadpool_worker_set_suspended (gboolean suspended)
1227 {
1228         if (!mono_refcount_tryinc (&worker))
1229                 return;
1230
1231         worker.suspended = suspended;
1232         if (!suspended)
1233                 worker_request ();
1234
1235         mono_refcount_dec (&worker);
1236 }