mono/metadata/threadpool-worker-default.c

   1 /*
   2  * threadpool-worker.c: native threadpool worker
   3  *
   4  * Author:
   5  *      Ludovic Henry (ludovic.henry@xamarin.com)
   6  *
   7  * Licensed under the MIT license. See LICENSE file in the project root for full license information.
   8  */
   9
  10 #include <stdlib.h>
  11 #define _USE_MATH_DEFINES // needed by MSVC to define math constants
  12 #include <math.h>
  13 #include <config.h>
  14 #include <glib.h>
  15
  16 #include <mono/metadata/class-internals.h>
  17 #include <mono/metadata/exception.h>
  18 #include <mono/metadata/gc-internals.h>
  19 #include <mono/metadata/object.h>
  20 #include <mono/metadata/object-internals.h>
  21 #include <mono/metadata/threadpool.h>
  22 #include <mono/metadata/threadpool-worker.h>
  23 #include <mono/metadata/threadpool-io.h>
  24 #include <mono/metadata/w32event.h>
  25 #include <mono/utils/atomic.h>
  26 #include <mono/utils/mono-compiler.h>
  27 #include <mono/utils/mono-complex.h>
  28 #include <mono/utils/mono-lazy-init.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/io-layer/io-layer.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 MonoInternalThread ThreadPoolWorkerThread;
 129
 130 struct MonoThreadPoolWorker {
 131         MonoRefCount ref;
 132
 133         ThreadPoolWorkerCounter counters;
 134
 135         GPtrArray *threads; // ThreadPoolWorkerThread* []
 136         MonoCoopMutex threads_lock; /* protect access to working_threads and parked_threads */
 137         gint32 parked_threads_count;
 138         MonoCoopCond parked_threads_cond;
 139         MonoCoopCond threads_exit_cond;
 140
 141         ThreadPoolWorkItem *work_items; // ThreadPoolWorkItem []
 142         gint32 work_items_count;
 143         gint32 work_items_size;
 144         MonoCoopMutex work_items_lock;
 145
 146         guint32 worker_creation_current_second;
 147         guint32 worker_creation_current_count;
 148         MonoCoopMutex worker_creation_lock;
 149
 150         gint32 heuristic_completions;
 151         gint64 heuristic_sample_start;
 152         gint64 heuristic_last_dequeue; // ms
 153         gint64 heuristic_last_adjustment; // ms
 154         gint64 heuristic_adjustment_interval; // ms
 155         ThreadPoolHillClimbing heuristic_hill_climbing;
 156         MonoCoopMutex heuristic_lock;
 157
 158         gint32 limit_worker_min;
 159         gint32 limit_worker_max;
 160
 161         MonoCpuUsageState *cpu_usage_state;
 162         gint32 cpu_usage;
 163
 164         /* suspended by the debugger */
 165         gboolean suspended;
 166
 167         gint32 monitor_status;
 168 };
 169
 170 enum {
 171         MONITOR_STATUS_REQUESTED,
 172         MONITOR_STATUS_WAITING_FOR_REQUEST,
 173         MONITOR_STATUS_NOT_RUNNING,
 174 };
 175
 176 #define COUNTER_CHECK(counter) \
 177         do { \
 178                 g_assert (counter._.max_working > 0); \
 179                 g_assert (counter._.starting >= 0); \
 180                 g_assert (counter._.working >= 0); \
 181         } while (0)
 182
 183 #define COUNTER_ATOMIC(worker,var,block) \
 184         do { \
 185                 ThreadPoolWorkerCounter __old; \
 186                 do { \
 187                         g_assert (worker); \
 188                         __old = COUNTER_READ (worker); \
 189                         (var) = __old; \
 190                         { block; } \
 191                         COUNTER_CHECK (var); \
 192                 } while (InterlockedCompareExchange64 (&worker->counters.as_gint64, (var).as_gint64, __old.as_gint64) != __old.as_gint64); \
 193         } while (0)
 194
 195 static inline ThreadPoolWorkerCounter
 196 COUNTER_READ (MonoThreadPoolWorker *worker)
 197 {
 198         ThreadPoolWorkerCounter counter;
 199         counter.as_gint64 = InterlockedRead64 (&worker->counters.as_gint64);
 200         return counter;
 201 }
 202
 203 static gpointer
 204 rand_create (void)
 205 {
 206         mono_rand_open ();
 207         return mono_rand_init (NULL, 0);
 208 }
 209
 210 static guint32
 211 rand_next (gpointer *handle, guint32 min, guint32 max)
 212 {
 213         MonoError error;
 214         guint32 val;
 215         mono_rand_try_get_uint32 (handle, &val, min, max, &error);
 216         // FIXME handle error
 217         mono_error_assert_ok (&error);
 218         return val;
 219 }
 220
 221 static void
 222 destroy (gpointer data)
 223 {
 224         MonoThreadPoolWorker *worker;
 225
 226         worker = (MonoThreadPoolWorker*) data;
 227         g_assert (worker);
 228
 229         // FIXME destroy everything
 230
 231         g_free (worker);
 232 }
 233
 234 void
 235 mono_threadpool_worker_init (MonoThreadPoolWorker **worker)
 236 {
 237         MonoThreadPoolWorker *wk;
 238         ThreadPoolHillClimbing *hc;
 239         const char *threads_per_cpu_env;
 240         gint threads_per_cpu;
 241         gint threads_count;
 242
 243         g_assert (worker);
 244
 245         wk = *worker = g_new0 (MonoThreadPoolWorker, 1);
 246
 247         mono_refcount_init (wk, destroy);
 248
 249         wk->threads = g_ptr_array_new ();
 250         mono_coop_mutex_init (&wk->threads_lock);
 251         wk->parked_threads_count = 0;
 252         mono_coop_cond_init (&wk->parked_threads_cond);
 253         mono_coop_cond_init (&wk->threads_exit_cond);
 254
 255         /* wk->work_items_size is inited to 0 */
 256         mono_coop_mutex_init (&wk->work_items_lock);
 257
 258         wk->worker_creation_current_second = -1;
 259         mono_coop_mutex_init (&wk->worker_creation_lock);
 260
 261         wk->heuristic_adjustment_interval = 10;
 262         mono_coop_mutex_init (&wk->heuristic_lock);
 263
 264         mono_rand_open ();
 265
 266         hc = &wk->heuristic_hill_climbing;
 267
 268         hc->wave_period = HILL_CLIMBING_WAVE_PERIOD;
 269         hc->max_thread_wave_magnitude = HILL_CLIMBING_MAX_WAVE_MAGNITUDE;
 270         hc->thread_magnitude_multiplier = (gdouble) HILL_CLIMBING_WAVE_MAGNITUDE_MULTIPLIER;
 271         hc->samples_to_measure = hc->wave_period * HILL_CLIMBING_WAVE_HISTORY_SIZE;
 272         hc->target_throughput_ratio = (gdouble) HILL_CLIMBING_BIAS;
 273         hc->target_signal_to_noise_ratio = (gdouble) HILL_CLIMBING_TARGET_SIGNAL_TO_NOISE_RATIO;
 274         hc->max_change_per_second = (gdouble) HILL_CLIMBING_MAX_CHANGE_PER_SECOND;
 275         hc->max_change_per_sample = (gdouble) HILL_CLIMBING_MAX_CHANGE_PER_SAMPLE;
 276         hc->sample_interval_low = HILL_CLIMBING_SAMPLE_INTERVAL_LOW;
 277         hc->sample_interval_high = HILL_CLIMBING_SAMPLE_INTERVAL_HIGH;
 278         hc->throughput_error_smoothing_factor = (gdouble) HILL_CLIMBING_ERROR_SMOOTHING_FACTOR;
 279         hc->gain_exponent = (gdouble) HILL_CLIMBING_GAIN_EXPONENT;
 280         hc->max_sample_error = (gdouble) HILL_CLIMBING_MAX_SAMPLE_ERROR_PERCENT;
 281         hc->current_control_setting = 0;
 282         hc->total_samples = 0;
 283         hc->last_thread_count = 0;
 284         hc->average_throughput_noise = 0;
 285         hc->elapsed_since_last_change = 0;
 286         hc->accumulated_completion_count = 0;
 287         hc->accumulated_sample_duration = 0;
 288         hc->samples = g_new0 (gdouble, hc->samples_to_measure);
 289         hc->thread_counts = g_new0 (gdouble, hc->samples_to_measure);
 290         hc->random_interval_generator = rand_create ();
 291         hc->current_sample_interval = rand_next (&hc->random_interval_generator, hc->sample_interval_low, hc->sample_interval_high);
 292
 293         if (!(threads_per_cpu_env = g_getenv ("MONO_THREADS_PER_CPU")))
 294                 threads_per_cpu = 1;
 295         else
 296                 threads_per_cpu = CLAMP (atoi (threads_per_cpu_env), 1, 50);
 297
 298         threads_count = mono_cpu_count () * threads_per_cpu;
 299
 300         wk->limit_worker_min = threads_count;
 301
 302 #if defined (PLATFORM_ANDROID) || defined (HOST_IOS)
 303         wk->limit_worker_max = CLAMP (threads_count * 100, MIN (threads_count, 200), MAX (threads_count, 200));
 304 #else
 305         wk->limit_worker_max = threads_count * 100;
 306 #endif
 307
 308         wk->counters._.max_working = wk->limit_worker_min;
 309
 310         wk->cpu_usage_state = g_new0 (MonoCpuUsageState, 1);
 311
 312         wk->suspended = FALSE;
 313
 314         wk->monitor_status = MONITOR_STATUS_NOT_RUNNING;
 315 }
 316
 317 void
 318 mono_threadpool_worker_cleanup (MonoThreadPoolWorker *worker)
 319 {
 320         MonoInternalThread *current;
 321
 322         /* we make the assumption along the code that we are
 323          * cleaning up only if the runtime is shutting down */
 324         g_assert (mono_runtime_is_shutting_down ());
 325
 326         current = mono_thread_internal_current ();
 327
 328         while (worker->monitor_status != MONITOR_STATUS_NOT_RUNNING)
 329                 mono_thread_info_sleep (1, NULL);
 330
 331         mono_coop_mutex_lock (&worker->threads_lock);
 332
 333         /* unpark all worker->parked_threads */
 334         mono_coop_cond_broadcast (&worker->parked_threads_cond);
 335
 336         for (;;) {
 337                 ThreadPoolWorkerCounter counter;
 338
 339                 counter = COUNTER_READ (worker);
 340                 if (counter._.starting + counter._.working + counter._.parked == 0)
 341                         break;
 342
 343                 if (counter._.starting + counter._.working + counter._.parked == 1) {
 344                         if (worker->threads->len == 1 && g_ptr_array_index (worker->threads, 0) == current) {
 345                                 /* We are waiting on ourselves */
 346                                 break;
 347                         }
 348                 }
 349
 350                 mono_coop_cond_wait (&worker->threads_exit_cond, &worker->threads_lock);
 351         }
 352
 353         mono_coop_mutex_unlock (&worker->threads_lock);
 354
 355         mono_refcount_dec (worker);
 356 }
 357
 358 static void
 359 work_item_lock (MonoThreadPoolWorker *worker)
 360 {
 361         mono_coop_mutex_lock (&worker->work_items_lock);
 362 }
 363
 364 static void
 365 work_item_unlock (MonoThreadPoolWorker *worker)
 366 {
 367         mono_coop_mutex_unlock (&worker->work_items_lock);
 368 }
 369
 370 static void
 371 work_item_push (MonoThreadPoolWorker *worker, MonoThreadPoolWorkerCallback callback, gpointer data)
 372 {
 373         ThreadPoolWorkItem work_item;
 374
 375         g_assert (worker);
 376         g_assert (callback);
 377
 378         work_item.callback = callback;
 379         work_item.data = data;
 380
 381         work_item_lock (worker);
 382
 383         g_assert (worker->work_items_count <= worker->work_items_size);
 384
 385         if (G_UNLIKELY (worker->work_items_count == worker->work_items_size)) {
 386                 worker->work_items_size += 64;
 387                 worker->work_items = g_renew (ThreadPoolWorkItem, worker->work_items, worker->work_items_size);
 388         }
 389
 390         g_assert (worker->work_items);
 391
 392         worker->work_items [worker->work_items_count ++] = work_item;
 393
 394         // printf ("[push] worker->work_items = %p, worker->work_items_count = %d, worker->work_items_size = %d\n",
 395         //      worker->work_items, worker->work_items_count, worker->work_items_size);
 396
 397         work_item_unlock (worker);
 398 }
 399
 400 static gboolean
 401 work_item_try_pop (MonoThreadPoolWorker *worker, ThreadPoolWorkItem *work_item)
 402 {
 403         g_assert (worker);
 404         g_assert (work_item);
 405
 406         work_item_lock (worker);
 407
 408         // printf ("[pop]  worker->work_items = %p, worker->work_items_count = %d, worker->work_items_size = %d\n",
 409         //      worker->work_items, worker->work_items_count, worker->work_items_size);
 410
 411         if (worker->work_items_count == 0) {
 412                 work_item_unlock (worker);
 413                 return FALSE;
 414         }
 415
 416         *work_item = worker->work_items [-- worker->work_items_count];
 417
 418         if (G_UNLIKELY (worker->work_items_count >= 64 * 3 && worker->work_items_count < worker->work_items_size / 2)) {
 419                 worker->work_items_size -= 64;
 420                 worker->work_items = g_renew (ThreadPoolWorkItem, worker->work_items, worker->work_items_size);
 421         }
 422
 423         work_item_unlock (worker);
 424
 425         return TRUE;
 426 }
 427
 428 static gint32
 429 work_item_count (MonoThreadPoolWorker *worker)
 430 {
 431         gint32 count;
 432
 433         work_item_lock (worker);
 434         count = worker->work_items_count;
 435         work_item_unlock (worker);
 436
 437         return count;
 438 }
 439
 440 static void worker_request (MonoThreadPoolWorker *worker);
 441
 442 void
 443 mono_threadpool_worker_enqueue (MonoThreadPoolWorker *worker, MonoThreadPoolWorkerCallback callback, gpointer data)
 444 {
 445         work_item_push (worker, callback, data);
 446
 447         worker_request (worker);
 448 }
 449
 450 static void
 451 worker_wait_interrupt (gpointer data)
 452 {
 453         MonoThreadPoolWorker *worker;
 454
 455         worker = (MonoThreadPoolWorker*) data;
 456         g_assert (worker);
 457
 458         mono_coop_mutex_lock (&worker->threads_lock);
 459         mono_coop_cond_signal (&worker->parked_threads_cond);
 460         mono_coop_mutex_unlock (&worker->threads_lock);
 461
 462         mono_refcount_dec (worker);
 463 }
 464
 465 /* return TRUE if timeout, FALSE otherwise (worker unpark or interrupt) */
 466 static gboolean
 467 worker_park (MonoThreadPoolWorker *worker)
 468 {
 469         gboolean timeout = FALSE;
 470
 471         mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] worker parking", mono_native_thread_id_get ());
 472
 473         mono_coop_mutex_lock (&worker->threads_lock);
 474
 475         if (!mono_runtime_is_shutting_down ()) {
 476                 static gpointer rand_handle = NULL;
 477                 MonoInternalThread *thread;
 478                 gboolean interrupted = FALSE;
 479                 ThreadPoolWorkerCounter counter;
 480
 481                 if (!rand_handle)
 482                         rand_handle = rand_create ();
 483                 g_assert (rand_handle);
 484
 485                 thread = mono_thread_internal_current ();
 486                 g_assert (thread);
 487
 488                 COUNTER_ATOMIC (worker, counter, {
 489                         counter._.working --;
 490                         counter._.parked ++;
 491                 });
 492
 493                 worker->parked_threads_count += 1;
 494
 495                 mono_thread_info_install_interrupt (worker_wait_interrupt, mono_refcount_inc (worker), &interrupted);
 496                 if (interrupted) {
 497                         mono_refcount_dec (worker);
 498                         goto done;
 499                 }
 500
 501                 if (mono_coop_cond_timedwait (&worker->parked_threads_cond, &worker->threads_lock, rand_next (&rand_handle, 5 * 1000, 60 * 1000)) != 0)
 502                         timeout = TRUE;
 503
 504                 mono_thread_info_uninstall_interrupt (&interrupted);
 505                 if (!interrupted)
 506                         mono_refcount_dec (worker);
 507
 508 done:
 509                 worker->parked_threads_count -= 1;
 510
 511                 COUNTER_ATOMIC (worker, counter, {
 512                         counter._.working ++;
 513                         counter._.parked --;
 514                 });
 515         }
 516
 517         mono_coop_mutex_unlock (&worker->threads_lock);
 518
 519         mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] worker unparking, timeout? %s", mono_native_thread_id_get (), timeout ? "yes" : "no");
 520
 521         return timeout;
 522 }
 523
 524 static gboolean
 525 worker_try_unpark (MonoThreadPoolWorker *worker)
 526 {
 527         gboolean res = FALSE;
 528
 529         mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] try unpark worker", mono_native_thread_id_get ());
 530
 531         mono_coop_mutex_lock (&worker->threads_lock);
 532         if (worker->parked_threads_count > 0) {
 533                 mono_coop_cond_signal (&worker->parked_threads_cond);
 534                 res = TRUE;
 535         }
 536         mono_coop_mutex_unlock (&worker->threads_lock);
 537
 538         mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] try unpark worker, success? %s", mono_native_thread_id_get (), res ? "yes" : "no");
 539
 540         return res;
 541 }
 542
 543 static gsize WINAPI
 544 worker_thread (gpointer data)
 545 {
 546         MonoThreadPoolWorker *worker;
 547         MonoError error;
 548         MonoInternalThread *thread;
 549         ThreadPoolWorkerCounter counter;
 550
 551         mono_trace (G_LOG_LEVEL_INFO, MONO_TRACE_THREADPOOL, "[%p] worker starting", mono_native_thread_id_get ());
 552
 553         worker = (MonoThreadPoolWorker*) data;
 554         g_assert (worker);
 555
 556         COUNTER_ATOMIC (worker, counter, {
 557                 counter._.starting --;
 558                 counter._.working ++;
 559         });
 560
 561         thread = mono_thread_internal_current ();
 562         g_assert (thread);
 563
 564         mono_coop_mutex_lock (&worker->threads_lock);
 565         g_ptr_array_add (worker->threads, thread);
 566         mono_coop_mutex_unlock (&worker->threads_lock);
 567
 568         mono_thread_set_name_internal (thread, mono_string_new (mono_get_root_domain (), "Threadpool worker"), FALSE, &error);
 569         mono_error_assert_ok (&error);
 570
 571         while (!mono_runtime_is_shutting_down ()) {
 572                 ThreadPoolWorkItem work_item;
 573
 574                 if (mono_thread_interruption_checkpoint ())
 575                         continue;
 576
 577                 if (!work_item_try_pop (worker, &work_item)) {
 578                         gboolean timeout;
 579
 580                         timeout = worker_park (worker);
 581                         if (timeout)
 582                                 break;
 583
 584                         continue;
 585                 }
 586
 587                 mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] worker executing %p (%p)",
 588                         mono_native_thread_id_get (), work_item.callback, work_item.data);
 589
 590                 work_item.callback (work_item.data);
 591         }
 592
 593         mono_coop_mutex_lock (&worker->threads_lock);
 594
 595         COUNTER_ATOMIC (worker, counter, {
 596                 counter._.working --;
 597         });
 598
 599         g_ptr_array_remove (worker->threads, thread);
 600
 601         mono_coop_cond_signal (&worker->threads_exit_cond);
 602
 603         mono_coop_mutex_unlock (&worker->threads_lock);
 604
 605         mono_trace (G_LOG_LEVEL_INFO, MONO_TRACE_THREADPOOL, "[%p] worker finishing", mono_native_thread_id_get ());
 606
 607         mono_refcount_dec (worker);
 608
 609         return 0;
 610 }
 611
 612 static gboolean
 613 worker_try_create (MonoThreadPoolWorker *worker)
 614 {
 615         MonoError error;
 616         MonoInternalThread *thread;
 617         gint64 current_ticks;
 618         gint32 now;
 619         ThreadPoolWorkerCounter counter;
 620
 621         if (mono_runtime_is_shutting_down ())
 622                 return FALSE;
 623
 624         mono_coop_mutex_lock (&worker->worker_creation_lock);
 625
 626         mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] try create worker", mono_native_thread_id_get ());
 627
 628         current_ticks = mono_100ns_ticks ();
 629         if (0 == current_ticks) {
 630                 g_warning ("failed to get 100ns ticks");
 631         } else {
 632                 now = current_ticks / (10 * 1000 * 1000);
 633                 if (worker->worker_creation_current_second != now) {
 634                         worker->worker_creation_current_second = now;
 635                         worker->worker_creation_current_count = 0;
 636                 } else {
 637                         g_assert (worker->worker_creation_current_count <= WORKER_CREATION_MAX_PER_SEC);
 638                         if (worker->worker_creation_current_count == WORKER_CREATION_MAX_PER_SEC) {
 639                                 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",
 640                                         mono_native_thread_id_get (), worker->worker_creation_current_count);
 641                                 mono_coop_mutex_unlock (&worker->worker_creation_lock);
 642                                 return FALSE;
 643                         }
 644                 }
 645         }
 646
 647         COUNTER_ATOMIC (worker, counter, {
 648                 if (counter._.working >= counter._.max_working) {
 649                         mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] try create worker, failed: maximum number of working threads reached",
 650                                 mono_native_thread_id_get ());
 651                         mono_coop_mutex_unlock (&worker->worker_creation_lock);
 652                         return FALSE;
 653                 }
 654                 counter._.starting ++;
 655         });
 656
 657         thread = mono_thread_create_internal (mono_get_root_domain (), worker_thread, mono_refcount_inc (worker), TRUE, 0, &error);
 658         if (!thread) {
 659                 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));
 660                 mono_error_cleanup (&error);
 661
 662                 COUNTER_ATOMIC (worker, counter, {
 663                         counter._.starting --;
 664                 });
 665
 666                 mono_coop_mutex_unlock (&worker->worker_creation_lock);
 667
 668                 mono_refcount_dec (worker);
 669
 670                 return FALSE;
 671         }
 672
 673         worker->worker_creation_current_count += 1;
 674
 675         mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] try create worker, created %p, now = %d count = %d",
 676                 mono_native_thread_id_get (), (gpointer) thread->tid, now, worker->worker_creation_current_count);
 677
 678         mono_coop_mutex_unlock (&worker->worker_creation_lock);
 679         return TRUE;
 680 }
 681
 682 static void monitor_ensure_running (MonoThreadPoolWorker *worker);
 683
 684 static void
 685 worker_request (MonoThreadPoolWorker *worker)
 686 {
 687         g_assert (worker);
 688
 689         if (worker->suspended)
 690                 return;
 691
 692         monitor_ensure_running (worker);
 693
 694         if (worker_try_unpark (worker)) {
 695                 mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] request worker, unparked", mono_native_thread_id_get ());
 696                 return;
 697         }
 698
 699         if (worker_try_create (worker)) {
 700                 mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] request worker, created", mono_native_thread_id_get ());
 701                 return;
 702         }
 703
 704         mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] request worker, failed", mono_native_thread_id_get ());
 705 }
 706
 707 static gboolean
 708 monitor_should_keep_running (MonoThreadPoolWorker *worker)
 709 {
 710         static gint64 last_should_keep_running = -1;
 711
 712         g_assert (worker->monitor_status == MONITOR_STATUS_WAITING_FOR_REQUEST || worker->monitor_status == MONITOR_STATUS_REQUESTED);
 713
 714         if (InterlockedExchange (&worker->monitor_status, MONITOR_STATUS_WAITING_FOR_REQUEST) == MONITOR_STATUS_WAITING_FOR_REQUEST) {
 715                 gboolean should_keep_running = TRUE, force_should_keep_running = FALSE;
 716
 717                 if (mono_runtime_is_shutting_down ()) {
 718                         should_keep_running = FALSE;
 719                 } else {
 720                         if (work_item_count (worker) == 0)
 721                                 should_keep_running = FALSE;
 722
 723                         if (!should_keep_running) {
 724                                 if (last_should_keep_running == -1 || mono_100ns_ticks () - last_should_keep_running < MONITOR_MINIMAL_LIFETIME * 1000 * 10) {
 725                                         should_keep_running = force_should_keep_running = TRUE;
 726                                 }
 727                         }
 728                 }
 729
 730                 if (should_keep_running) {
 731                         if (last_should_keep_running == -1 || !force_should_keep_running)
 732                                 last_should_keep_running = mono_100ns_ticks ();
 733                 } else {
 734                         last_should_keep_running = -1;
 735                         if (InterlockedCompareExchange (&worker->monitor_status, MONITOR_STATUS_NOT_RUNNING, MONITOR_STATUS_WAITING_FOR_REQUEST) == MONITOR_STATUS_WAITING_FOR_REQUEST)
 736                                 return FALSE;
 737                 }
 738         }
 739
 740         g_assert (worker->monitor_status == MONITOR_STATUS_WAITING_FOR_REQUEST || worker->monitor_status == MONITOR_STATUS_REQUESTED);
 741
 742         return TRUE;
 743 }
 744
 745 static gboolean
 746 monitor_sufficient_delay_since_last_dequeue (MonoThreadPoolWorker *worker)
 747 {
 748         gint64 threshold;
 749
 750         g_assert (worker);
 751
 752         if (worker->cpu_usage < CPU_USAGE_LOW) {
 753                 threshold = MONITOR_INTERVAL;
 754         } else {
 755                 ThreadPoolWorkerCounter counter;
 756                 counter = COUNTER_READ (worker);
 757                 threshold = counter._.max_working * MONITOR_INTERVAL * 2;
 758         }
 759
 760         return mono_msec_ticks () >= worker->heuristic_last_dequeue + threshold;
 761 }
 762
 763 static void hill_climbing_force_change (MonoThreadPoolWorker *worker, gint16 new_thread_count, ThreadPoolHeuristicStateTransition transition);
 764
 765 static gsize WINAPI
 766 monitor_thread (gpointer data)
 767 {
 768         MonoThreadPoolWorker *worker;
 769         MonoInternalThread *internal;
 770         guint i;
 771
 772         worker = (MonoThreadPoolWorker*) data;
 773         g_assert (worker);
 774
 775         internal = mono_thread_internal_current ();
 776         g_assert (internal);
 777
 778         mono_cpu_usage (worker->cpu_usage_state);
 779
 780         // printf ("monitor_thread: start\n");
 781
 782         mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] monitor thread, started", mono_native_thread_id_get ());
 783
 784         do {
 785                 ThreadPoolWorkerCounter counter;
 786                 gboolean limit_worker_max_reached;
 787                 gint32 interval_left = MONITOR_INTERVAL;
 788                 gint32 awake = 0; /* number of spurious awakes we tolerate before doing a round of rebalancing */
 789
 790                 g_assert (worker->monitor_status != MONITOR_STATUS_NOT_RUNNING);
 791
 792                 // counter = COUNTER_READ (worker);
 793                 // printf ("monitor_thread: starting = %d working = %d parked = %d max_working = %d\n",
 794                 //      counter._.starting, counter._.working, counter._.parked, counter._.max_working);
 795
 796                 do {
 797                         gint64 ts;
 798                         gboolean alerted = FALSE;
 799
 800                         if (mono_runtime_is_shutting_down ())
 801                                 break;
 802
 803                         ts = mono_msec_ticks ();
 804                         if (mono_thread_info_sleep (interval_left, &alerted) == 0)
 805                                 break;
 806                         interval_left -= mono_msec_ticks () - ts;
 807
 808                         g_assert (!(internal->state & ThreadState_StopRequested));
 809                         mono_thread_interruption_checkpoint ();
 810                 } while (interval_left > 0 && ++awake < 10);
 811
 812                 if (mono_runtime_is_shutting_down ())
 813                         continue;
 814
 815                 if (worker->suspended)
 816                         continue;
 817
 818                 if (work_item_count (worker) == 0)
 819                         continue;
 820
 821                 worker->cpu_usage = mono_cpu_usage (worker->cpu_usage_state);
 822
 823                 if (!monitor_sufficient_delay_since_last_dequeue (worker))
 824                         continue;
 825
 826                 limit_worker_max_reached = FALSE;
 827
 828                 COUNTER_ATOMIC (worker, counter, {
 829                         if (counter._.max_working >= worker->limit_worker_max) {
 830                                 limit_worker_max_reached = TRUE;
 831                                 break;
 832                         }
 833                         counter._.max_working ++;
 834                 });
 835
 836                 if (limit_worker_max_reached)
 837                         continue;
 838
 839                 hill_climbing_force_change (worker, counter._.max_working, TRANSITION_STARVATION);
 840
 841                 for (i = 0; i < 5; ++i) {
 842                         if (mono_runtime_is_shutting_down ())
 843                                 break;
 844
 845                         if (worker_try_unpark (worker)) {
 846                                 mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] monitor thread, unparked", mono_native_thread_id_get ());
 847                                 break;
 848                         }
 849
 850                         if (worker_try_create (worker)) {
 851                                 mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] monitor thread, created", mono_native_thread_id_get ());
 852                                 break;
 853                         }
 854                 }
 855         } while (monitor_should_keep_running (worker));
 856
 857         // printf ("monitor_thread: stop\n");
 858
 859         mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] monitor thread, finished", mono_native_thread_id_get ());
 860
 861         return 0;
 862 }
 863
 864 static void
 865 monitor_ensure_running (MonoThreadPoolWorker *worker)
 866 {
 867         MonoError error;
 868         for (;;) {
 869                 switch (worker->monitor_status) {
 870                 case MONITOR_STATUS_REQUESTED:
 871                         // printf ("monitor_thread: requested\n");
 872                         return;
 873                 case MONITOR_STATUS_WAITING_FOR_REQUEST:
 874                         // printf ("monitor_thread: waiting for request\n");
 875                         InterlockedCompareExchange (&worker->monitor_status, MONITOR_STATUS_REQUESTED, MONITOR_STATUS_WAITING_FOR_REQUEST);
 876                         break;
 877                 case MONITOR_STATUS_NOT_RUNNING:
 878                         // printf ("monitor_thread: not running\n");
 879                         if (mono_runtime_is_shutting_down ())
 880                                 return;
 881                         if (InterlockedCompareExchange (&worker->monitor_status, MONITOR_STATUS_REQUESTED, MONITOR_STATUS_NOT_RUNNING) == MONITOR_STATUS_NOT_RUNNING) {
 882                                 // printf ("monitor_thread: creating\n");
 883                                 if (!mono_thread_create_internal (mono_get_root_domain (), monitor_thread, worker, TRUE, SMALL_STACK, &error)) {
 884                                         // printf ("monitor_thread: creating failed\n");
 885                                         worker->monitor_status = MONITOR_STATUS_NOT_RUNNING;
 886                                         mono_error_cleanup (&error);
 887                                 }
 888                                 return;
 889                         }
 890                         break;
 891                 default: g_assert_not_reached ();
 892                 }
 893         }
 894 }
 895
 896 static void
 897 hill_climbing_change_thread_count (MonoThreadPoolWorker *worker, gint16 new_thread_count, ThreadPoolHeuristicStateTransition transition)
 898 {
 899         ThreadPoolHillClimbing *hc;
 900
 901         g_assert (worker);
 902
 903         hc = &worker->heuristic_hill_climbing;
 904
 905         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);
 906
 907         hc->last_thread_count = new_thread_count;
 908         hc->current_sample_interval = rand_next (&hc->random_interval_generator, hc->sample_interval_low, hc->sample_interval_high);
 909         hc->elapsed_since_last_change = 0;
 910         hc->completions_since_last_change = 0;
 911 }
 912
 913 static void
 914 hill_climbing_force_change (MonoThreadPoolWorker *worker, gint16 new_thread_count, ThreadPoolHeuristicStateTransition transition)
 915 {
 916         ThreadPoolHillClimbing *hc;
 917
 918         g_assert (worker);
 919
 920         hc = &worker->heuristic_hill_climbing;
 921
 922         if (new_thread_count != hc->last_thread_count) {
 923                 hc->current_control_setting += new_thread_count - hc->last_thread_count;
 924                 hill_climbing_change_thread_count (worker, new_thread_count, transition);
 925         }
 926 }
 927
 928 static double_complex
 929 hill_climbing_get_wave_component (MonoThreadPoolWorker *worker, gdouble *samples, guint sample_count, gdouble period)
 930 {
 931         ThreadPoolHillClimbing *hc;
 932         gdouble w, cosine, sine, coeff, q0, q1, q2;
 933         guint i;
 934
 935         g_assert (worker);
 936         g_assert (sample_count >= period);
 937         g_assert (period >= 2);
 938
 939         hc = &worker->heuristic_hill_climbing;
 940
 941         w = 2.0 * M_PI / period;
 942         cosine = cos (w);
 943         sine = sin (w);
 944         coeff = 2.0 * cosine;
 945         q0 = q1 = q2 = 0;
 946
 947         for (i = 0; i < sample_count; ++i) {
 948                 q0 = coeff * q1 - q2 + samples [(hc->total_samples - sample_count + i) % hc->samples_to_measure];
 949                 q2 = q1;
 950                 q1 = q0;
 951         }
 952
 953         return mono_double_complex_scalar_div (mono_double_complex_make (q1 - q2 * cosine, (q2 * sine)), ((gdouble)sample_count));
 954 }
 955
 956 static gint16
 957 hill_climbing_update (MonoThreadPoolWorker *worker, gint16 current_thread_count, guint32 sample_duration, gint32 completions, gint64 *adjustment_interval)
 958 {
 959         ThreadPoolHillClimbing *hc;
 960         ThreadPoolHeuristicStateTransition transition;
 961         gdouble throughput;
 962         gdouble throughput_error_estimate;
 963         gdouble confidence;
 964         gdouble move;
 965         gdouble gain;
 966         gint sample_index;
 967         gint sample_count;
 968         gint new_thread_wave_magnitude;
 969         gint new_thread_count;
 970         double_complex thread_wave_component;
 971         double_complex throughput_wave_component;
 972         double_complex ratio;
 973
 974         g_assert (worker);
 975         g_assert (adjustment_interval);
 976
 977         hc = &worker->heuristic_hill_climbing;
 978
 979         /* If someone changed the thread count without telling us, update our records accordingly. */
 980         if (current_thread_count != hc->last_thread_count)
 981                 hill_climbing_force_change (worker, current_thread_count, TRANSITION_INITIALIZING);
 982
 983         /* Update the cumulative stats for this thread count */
 984         hc->elapsed_since_last_change += sample_duration;
 985         hc->completions_since_last_change += completions;
 986
 987         /* Add in any data we've already collected about this sample */
 988         sample_duration += hc->accumulated_sample_duration;
 989         completions += hc->accumulated_completion_count;
 990
 991         /* We need to make sure we're collecting reasonably accurate data. Since we're just counting the end
 992          * of each work item, we are goinng to be missing some data about what really happened during the
 993          * sample interval. The count produced by each thread includes an initial work item that may have
 994          * started well before the start of the interval, and each thread may have been running some new
 995          * work item for some time before the end of the interval, which did not yet get counted. So
 996          * our count is going to be off by +/- threadCount workitems.
 997          *
 998          * The exception is that the thread that reported to us last time definitely wasn't running any work
 999          * at that time, and the thread that's reporting now definitely isn't running a work item now. So
1000          * we really only need to consider threadCount-1 threads.
1001          *
1002          * Thus the percent error in our count is +/- (threadCount-1)/numCompletions.
1003          *
1004          * We cannot rely on the frequency-domain analysis we'll be doing later to filter out this error, because
1005          * of the way it accumulates over time. If this sample is off by, say, 33% in the negative direction,
1006          * then the next one likely will be too. The one after that will include the sum of the completions
1007          * we missed in the previous samples, and so will be 33% positive. So every three samples we'll have
1008          * two "low" samples and one "high" sample. This will appear as periodic variation right in the frequency
1009          * range we're targeting, which will not be filtered by the frequency-domain translation. */
1010         if (hc->total_samples > 0 && ((current_thread_count - 1.0) / completions) >= hc->max_sample_error) {
1011                 /* Not accurate enough yet. Let's accumulate the data so
1012                  * far, and tell the MonoThreadPoolWorker to collect a little more. */
1013                 hc->accumulated_sample_duration = sample_duration;
1014                 hc->accumulated_completion_count = completions;
1015                 *adjustment_interval = 10;
1016                 return current_thread_count;
1017         }
1018
1019         /* We've got enouugh data for our sample; reset our accumulators for next time. */
1020         hc->accumulated_sample_duration = 0;
1021         hc->accumulated_completion_count = 0;
1022
1023         /* Add the current thread count and throughput sample to our history. */
1024         throughput = ((gdouble) completions) / sample_duration;
1025
1026         sample_index = hc->total_samples % hc->samples_to_measure;
1027         hc->samples [sample_index] = throughput;
1028         hc->thread_counts [sample_index] = current_thread_count;
1029         hc->total_samples ++;
1030
1031         /* Set up defaults for our metrics. */
1032         thread_wave_component = mono_double_complex_make(0, 0);
1033         throughput_wave_component = mono_double_complex_make(0, 0);
1034         throughput_error_estimate = 0;
1035         ratio = mono_double_complex_make(0, 0);
1036         confidence = 0;
1037
1038         transition = TRANSITION_WARMUP;
1039
1040         /* How many samples will we use? It must be at least the three wave periods we're looking for, and it must also
1041          * be a whole multiple of the primary wave's period; otherwise the frequency we're looking for will fall between
1042          * two frequency bands in the Fourier analysis, and we won't be able to measure it accurately. */
1043         sample_count = ((gint) MIN (hc->total_samples - 1, hc->samples_to_measure) / hc->wave_period) * hc->wave_period;
1044
1045         if (sample_count > hc->wave_period) {
1046                 guint i;
1047                 gdouble average_throughput;
1048                 gdouble average_thread_count;
1049                 gdouble sample_sum = 0;
1050                 gdouble thread_sum = 0;
1051
1052                 /* Average the throughput and thread count samples, so we can scale the wave magnitudes later. */
1053                 for (i = 0; i < sample_count; ++i) {
1054                         guint j = (hc->total_samples - sample_count + i) % hc->samples_to_measure;
1055                         sample_sum += hc->samples [j];
1056                         thread_sum += hc->thread_counts [j];
1057                 }
1058
1059                 average_throughput = sample_sum / sample_count;
1060                 average_thread_count = thread_sum / sample_count;
1061
1062                 if (average_throughput > 0 && average_thread_count > 0) {
1063                         gdouble noise_for_confidence, adjacent_period_1, adjacent_period_2;
1064
1065                         /* Calculate the periods of the adjacent frequency bands we'll be using to
1066                          * measure noise levels. We want the two adjacent Fourier frequency bands. */
1067                         adjacent_period_1 = sample_count / (((gdouble) sample_count) / ((gdouble) hc->wave_period) + 1);
1068                         adjacent_period_2 = sample_count / (((gdouble) sample_count) / ((gdouble) hc->wave_period) - 1);
1069
1070                         /* Get the the three different frequency components of the throughput (scaled by average
1071                          * throughput). Our "error" estimate (the amount of noise that might be present in the
1072                          * frequency band we're really interested in) is the average of the adjacent bands. */
1073                         throughput_wave_component = mono_double_complex_scalar_div (hill_climbing_get_wave_component (worker, hc->samples, sample_count, hc->wave_period), average_throughput);
1074                         throughput_error_estimate = cabs (mono_double_complex_scalar_div (hill_climbing_get_wave_component (worker, hc->samples, sample_count, adjacent_period_1), average_throughput));
1075
1076                         if (adjacent_period_2 <= sample_count) {
1077                                 throughput_error_estimate = MAX (throughput_error_estimate, cabs (mono_double_complex_scalar_div (hill_climbing_get_wave_component (
1078                                         worker, hc->samples, sample_count, adjacent_period_2), average_throughput)));
1079                         }
1080
1081                         /* Do the same for the thread counts, so we have something to compare to. We don't
1082                          * measure thread count noise, because there is none; these are exact measurements. */
1083                         thread_wave_component = mono_double_complex_scalar_div (hill_climbing_get_wave_component (worker, hc->thread_counts, sample_count, hc->wave_period), average_thread_count);
1084
1085                         /* Update our moving average of the throughput noise. We'll use this
1086                          * later as feedback to determine the new size of the thread wave. */
1087                         if (hc->average_throughput_noise == 0) {
1088                                 hc->average_throughput_noise = throughput_error_estimate;
1089                         } else {
1090                                 hc->average_throughput_noise = (hc->throughput_error_smoothing_factor * throughput_error_estimate)
1091                                         + ((1.0 + hc->throughput_error_smoothing_factor) * hc->average_throughput_noise);
1092                         }
1093
1094                         if (cabs (thread_wave_component) > 0) {
1095                                 /* Adjust the throughput wave so it's centered around the target wave,
1096                                  * and then calculate the adjusted throughput/thread ratio. */
1097                                 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);
1098                                 transition = TRANSITION_CLIMBING_MOVE;
1099                         } else {
1100                                 ratio = mono_double_complex_make (0, 0);
1101                                 transition = TRANSITION_STABILIZING;
1102                         }
1103
1104                         noise_for_confidence = MAX (hc->average_throughput_noise, throughput_error_estimate);
1105                         if (noise_for_confidence > 0) {
1106                                 confidence = cabs (thread_wave_component) / noise_for_confidence / hc->target_signal_to_noise_ratio;
1107                         } else {
1108                                 /* there is no noise! */
1109                                 confidence = 1.0;
1110                         }
1111                 }
1112         }
1113
1114         /* We use just the real part of the complex ratio we just calculated. If the throughput signal
1115          * is exactly in phase with the thread signal, this will be the same as taking the magnitude of
1116          * the complex move and moving that far up. If they're 180 degrees out of phase, we'll move
1117          * backward (because this indicates that our changes are having the opposite of the intended effect).
1118          * If they're 90 degrees out of phase, we won't move at all, because we can't tell wether we're
1119          * having a negative or positive effect on throughput. */
1120         move = creal (ratio);
1121         move = CLAMP (move, -1.0, 1.0);
1122
1123         /* Apply our confidence multiplier. */
1124         move *= CLAMP (confidence, -1.0, 1.0);
1125
1126         /* Now apply non-linear gain, such that values around zero are attenuated, while higher values
1127          * are enhanced. This allows us to move quickly if we're far away from the target, but more slowly
1128         * if we're getting close, giving us rapid ramp-up without wild oscillations around the target. */
1129         gain = hc->max_change_per_second * sample_duration;
1130         move = pow (fabs (move), hc->gain_exponent) * (move >= 0.0 ? 1 : -1) * gain;
1131         move = MIN (move, hc->max_change_per_sample);
1132
1133         /* If the result was positive, and CPU is > 95%, refuse the move. */
1134         if (move > 0.0 && worker->cpu_usage > CPU_USAGE_HIGH)
1135                 move = 0.0;
1136
1137         /* Apply the move to our control setting. */
1138         hc->current_control_setting += move;
1139
1140         /* Calculate the new thread wave magnitude, which is based on the moving average we've been keeping of the
1141          * throughput error.  This average starts at zero, so we'll start with a nice safe little wave at first. */
1142         new_thread_wave_magnitude = (gint)(0.5 + (hc->current_control_setting * hc->average_throughput_noise
1143                 * hc->target_signal_to_noise_ratio * hc->thread_magnitude_multiplier * 2.0));
1144         new_thread_wave_magnitude = CLAMP (new_thread_wave_magnitude, 1, hc->max_thread_wave_magnitude);
1145
1146         /* Make sure our control setting is within the MonoThreadPoolWorker's limits. */
1147         hc->current_control_setting = CLAMP (hc->current_control_setting, worker->limit_worker_min, worker->limit_worker_max - new_thread_wave_magnitude);
1148
1149         /* Calculate the new thread count (control setting + square wave). */
1150         new_thread_count = (gint)(hc->current_control_setting + new_thread_wave_magnitude * ((hc->total_samples / (hc->wave_period / 2)) % 2));
1151
1152         /* Make sure the new thread count doesn't exceed the MonoThreadPoolWorker's limits. */
1153         new_thread_count = CLAMP (new_thread_count, worker->limit_worker_min, worker->limit_worker_max);
1154
1155         if (new_thread_count != current_thread_count)
1156                 hill_climbing_change_thread_count (worker, new_thread_count, transition);
1157
1158         if (creal (ratio) < 0.0 && new_thread_count == worker->limit_worker_min)
1159                 *adjustment_interval = (gint)(0.5 + hc->current_sample_interval * (10.0 * MAX (-1.0 * creal (ratio), 1.0)));
1160         else
1161                 *adjustment_interval = hc->current_sample_interval;
1162
1163         return new_thread_count;
1164 }
1165
1166 static gboolean
1167 heuristic_should_adjust (MonoThreadPoolWorker *worker)
1168 {
1169         if (worker->heuristic_last_dequeue > worker->heuristic_last_adjustment + worker->heuristic_adjustment_interval) {
1170                 ThreadPoolWorkerCounter counter;
1171                 counter = COUNTER_READ (worker);
1172                 if (counter._.working <= counter._.max_working)
1173                         return TRUE;
1174         }
1175
1176         return FALSE;
1177 }
1178
1179 static void
1180 heuristic_adjust (MonoThreadPoolWorker *worker)
1181 {
1182         if (mono_coop_mutex_trylock (&worker->heuristic_lock) == 0) {
1183                 gint32 completions = InterlockedExchange (&worker->heuristic_completions, 0);
1184                 gint64 sample_end = mono_msec_ticks ();
1185                 gint64 sample_duration = sample_end - worker->heuristic_sample_start;
1186
1187                 if (sample_duration >= worker->heuristic_adjustment_interval / 2) {
1188                         ThreadPoolWorkerCounter counter;
1189                         gint16 new_thread_count;
1190
1191                         counter = COUNTER_READ (worker);
1192                         new_thread_count = hill_climbing_update (worker, counter._.max_working, sample_duration, completions, &worker->heuristic_adjustment_interval);
1193
1194                         COUNTER_ATOMIC (worker, counter, {
1195                                 counter._.max_working = new_thread_count;
1196                         });
1197
1198                         if (new_thread_count > counter._.max_working)
1199                                 worker_request (worker);
1200
1201                         worker->heuristic_sample_start = sample_end;
1202                         worker->heuristic_last_adjustment = mono_msec_ticks ();
1203                 }
1204
1205                 mono_coop_mutex_unlock (&worker->heuristic_lock);
1206         }
1207 }
1208
1209 static void
1210 heuristic_notify_work_completed (MonoThreadPoolWorker *worker)
1211 {
1212         g_assert (worker);
1213
1214         InterlockedIncrement (&worker->heuristic_completions);
1215         worker->heuristic_last_dequeue = mono_msec_ticks ();
1216
1217         if (heuristic_should_adjust (worker))
1218                 heuristic_adjust (worker);
1219 }
1220
1221 gboolean
1222 mono_threadpool_worker_notify_completed (MonoThreadPoolWorker *worker)
1223 {
1224         ThreadPoolWorkerCounter counter;
1225
1226         heuristic_notify_work_completed (worker);
1227
1228         counter = COUNTER_READ (worker);
1229         return counter._.working <= counter._.max_working;
1230 }
1231
1232 gint32
1233 mono_threadpool_worker_get_min (MonoThreadPoolWorker *worker)
1234 {
1235         return worker->limit_worker_min;
1236 }
1237
1238 gboolean
1239 mono_threadpool_worker_set_min (MonoThreadPoolWorker *worker, gint32 value)
1240 {
1241         if (value <= 0 || value > worker->limit_worker_max)
1242                 return FALSE;
1243
1244         worker->limit_worker_min = value;
1245         return TRUE;
1246 }
1247
1248 gint32
1249 mono_threadpool_worker_get_max (MonoThreadPoolWorker *worker)
1250 {
1251         return worker->limit_worker_max;
1252 }
1253
1254 gboolean
1255 mono_threadpool_worker_set_max (MonoThreadPoolWorker *worker, gint32 value)
1256 {
1257         gint32 cpu_count = mono_cpu_count ();
1258
1259         if (value < worker->limit_worker_min || value < cpu_count)
1260                 return FALSE;
1261
1262         worker->limit_worker_max = value;
1263         return TRUE;
1264 }
1265
1266 void
1267 mono_threadpool_worker_set_suspended (MonoThreadPoolWorker *worker, gboolean suspended)
1268 {
1269         worker->suspended = suspended;
1270         if (!suspended)
1271                 worker_request (worker);
1272 }