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/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 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 #if 0
 337         for (;;) {
 338                 ThreadPoolWorkerCounter counter;
 339
 340                 counter = COUNTER_READ (worker);
 341                 if (counter._.starting + counter._.working + counter._.parked == 0)
 342                         break;
 343
 344                 if (counter._.starting + counter._.working + counter._.parked == 1) {
 345                         if (worker->threads->len == 1 && g_ptr_array_index (worker->threads, 0) == current) {
 346                                 /* We are waiting on ourselves */
 347                                 break;
 348                         }
 349                 }
 350
 351                 mono_coop_cond_wait (&worker->threads_exit_cond, &worker->threads_lock);
 352         }
 353 #endif
 354
 355         mono_coop_mutex_unlock (&worker->threads_lock);
 356
 357         mono_refcount_dec (worker);
 358 }
 359
 360 static void
 361 work_item_lock (MonoThreadPoolWorker *worker)
 362 {
 363         mono_coop_mutex_lock (&worker->work_items_lock);
 364 }
 365
 366 static void
 367 work_item_unlock (MonoThreadPoolWorker *worker)
 368 {
 369         mono_coop_mutex_unlock (&worker->work_items_lock);
 370 }
 371
 372 static void
 373 work_item_push (MonoThreadPoolWorker *worker, MonoThreadPoolWorkerCallback callback, gpointer data)
 374 {
 375         ThreadPoolWorkItem work_item;
 376
 377         g_assert (worker);
 378         g_assert (callback);
 379
 380         work_item.callback = callback;
 381         work_item.data = data;
 382
 383         work_item_lock (worker);
 384
 385         g_assert (worker->work_items_count <= worker->work_items_size);
 386
 387         if (G_UNLIKELY (worker->work_items_count == worker->work_items_size)) {
 388                 worker->work_items_size += 64;
 389                 worker->work_items = g_renew (ThreadPoolWorkItem, worker->work_items, worker->work_items_size);
 390         }
 391
 392         g_assert (worker->work_items);
 393
 394         worker->work_items [worker->work_items_count ++] = work_item;
 395
 396         // printf ("[push] worker->work_items = %p, worker->work_items_count = %d, worker->work_items_size = %d\n",
 397         //      worker->work_items, worker->work_items_count, worker->work_items_size);
 398
 399         work_item_unlock (worker);
 400 }
 401
 402 static gboolean
 403 work_item_try_pop (MonoThreadPoolWorker *worker, ThreadPoolWorkItem *work_item)
 404 {
 405         g_assert (worker);
 406         g_assert (work_item);
 407
 408         work_item_lock (worker);
 409
 410         // printf ("[pop]  worker->work_items = %p, worker->work_items_count = %d, worker->work_items_size = %d\n",
 411         //      worker->work_items, worker->work_items_count, worker->work_items_size);
 412
 413         if (worker->work_items_count == 0) {
 414                 work_item_unlock (worker);
 415                 return FALSE;
 416         }
 417
 418         *work_item = worker->work_items [-- worker->work_items_count];
 419
 420         if (G_UNLIKELY (worker->work_items_count >= 64 * 3 && worker->work_items_count < worker->work_items_size / 2)) {
 421                 worker->work_items_size -= 64;
 422                 worker->work_items = g_renew (ThreadPoolWorkItem, worker->work_items, worker->work_items_size);
 423         }
 424
 425         work_item_unlock (worker);
 426
 427         return TRUE;
 428 }
 429
 430 static gint32
 431 work_item_count (MonoThreadPoolWorker *worker)
 432 {
 433         gint32 count;
 434
 435         work_item_lock (worker);
 436         count = worker->work_items_count;
 437         work_item_unlock (worker);
 438
 439         return count;
 440 }
 441
 442 static void worker_request (MonoThreadPoolWorker *worker);
 443
 444 void
 445 mono_threadpool_worker_enqueue (MonoThreadPoolWorker *worker, MonoThreadPoolWorkerCallback callback, gpointer data)
 446 {
 447         work_item_push (worker, callback, data);
 448
 449         worker_request (worker);
 450 }
 451
 452 static void
 453 worker_wait_interrupt (gpointer data)
 454 {
 455         MonoThreadPoolWorker *worker;
 456
 457         worker = (MonoThreadPoolWorker*) data;
 458         g_assert (worker);
 459
 460         mono_coop_mutex_lock (&worker->threads_lock);
 461         mono_coop_cond_signal (&worker->parked_threads_cond);
 462         mono_coop_mutex_unlock (&worker->threads_lock);
 463
 464         mono_refcount_dec (worker);
 465 }
 466
 467 /* return TRUE if timeout, FALSE otherwise (worker unpark or interrupt) */
 468 static gboolean
 469 worker_park (MonoThreadPoolWorker *worker)
 470 {
 471         gboolean timeout = FALSE;
 472
 473         mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] worker parking", mono_native_thread_id_get ());
 474
 475         mono_coop_mutex_lock (&worker->threads_lock);
 476
 477         if (!mono_runtime_is_shutting_down ()) {
 478                 static gpointer rand_handle = NULL;
 479                 MonoInternalThread *thread;
 480                 gboolean interrupted = FALSE;
 481                 ThreadPoolWorkerCounter counter;
 482
 483                 if (!rand_handle)
 484                         rand_handle = rand_create ();
 485                 g_assert (rand_handle);
 486
 487                 thread = mono_thread_internal_current ();
 488                 g_assert (thread);
 489
 490                 COUNTER_ATOMIC (worker, counter, {
 491                         counter._.working --;
 492                         counter._.parked ++;
 493                 });
 494
 495                 worker->parked_threads_count += 1;
 496
 497                 mono_thread_info_install_interrupt (worker_wait_interrupt, mono_refcount_inc (worker), &interrupted);
 498                 if (interrupted) {
 499                         mono_refcount_dec (worker);
 500                         goto done;
 501                 }
 502
 503                 if (mono_coop_cond_timedwait (&worker->parked_threads_cond, &worker->threads_lock, rand_next (&rand_handle, 5 * 1000, 60 * 1000)) != 0)
 504                         timeout = TRUE;
 505
 506                 mono_thread_info_uninstall_interrupt (&interrupted);
 507                 if (!interrupted)
 508                         mono_refcount_dec (worker);
 509
 510 done:
 511                 worker->parked_threads_count -= 1;
 512
 513                 COUNTER_ATOMIC (worker, counter, {
 514                         counter._.working ++;
 515                         counter._.parked --;
 516                 });
 517         }
 518
 519         mono_coop_mutex_unlock (&worker->threads_lock);
 520
 521         mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] worker unparking, timeout? %s", mono_native_thread_id_get (), timeout ? "yes" : "no");
 522
 523         return timeout;
 524 }
 525
 526 static gboolean
 527 worker_try_unpark (MonoThreadPoolWorker *worker)
 528 {
 529         gboolean res = FALSE;
 530
 531         mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] try unpark worker", mono_native_thread_id_get ());
 532
 533         mono_coop_mutex_lock (&worker->threads_lock);
 534         if (worker->parked_threads_count > 0) {
 535                 mono_coop_cond_signal (&worker->parked_threads_cond);
 536                 res = TRUE;
 537         }
 538         mono_coop_mutex_unlock (&worker->threads_lock);
 539
 540         mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] try unpark worker, success? %s", mono_native_thread_id_get (), res ? "yes" : "no");
 541
 542         return res;
 543 }
 544
 545 static gsize WINAPI
 546 worker_thread (gpointer data)
 547 {
 548         MonoThreadPoolWorker *worker;
 549         MonoError error;
 550         MonoInternalThread *thread;
 551         ThreadPoolWorkerCounter counter;
 552
 553         mono_trace (G_LOG_LEVEL_INFO, MONO_TRACE_THREADPOOL, "[%p] worker starting", mono_native_thread_id_get ());
 554
 555         worker = (MonoThreadPoolWorker*) data;
 556         g_assert (worker);
 557
 558         COUNTER_ATOMIC (worker, counter, {
 559                 counter._.starting --;
 560                 counter._.working ++;
 561         });
 562
 563         thread = mono_thread_internal_current ();
 564         g_assert (thread);
 565
 566         mono_coop_mutex_lock (&worker->threads_lock);
 567         g_ptr_array_add (worker->threads, thread);
 568         mono_coop_mutex_unlock (&worker->threads_lock);
 569
 570         mono_thread_set_name_internal (thread, mono_string_new (mono_get_root_domain (), "Threadpool worker"), FALSE, &error);
 571         mono_error_assert_ok (&error);
 572
 573         while (!mono_runtime_is_shutting_down ()) {
 574                 ThreadPoolWorkItem work_item;
 575
 576                 if (mono_thread_interruption_checkpoint ())
 577                         continue;
 578
 579                 if (!work_item_try_pop (worker, &work_item)) {
 580                         gboolean timeout;
 581
 582                         timeout = worker_park (worker);
 583                         if (timeout)
 584                                 break;
 585
 586                         continue;
 587                 }
 588
 589                 mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] worker executing %p (%p)",
 590                         mono_native_thread_id_get (), work_item.callback, work_item.data);
 591
 592                 work_item.callback (work_item.data);
 593         }
 594
 595         mono_coop_mutex_lock (&worker->threads_lock);
 596
 597         COUNTER_ATOMIC (worker, counter, {
 598                 counter._.working --;
 599         });
 600
 601         g_ptr_array_remove (worker->threads, thread);
 602
 603         mono_coop_cond_signal (&worker->threads_exit_cond);
 604
 605         mono_coop_mutex_unlock (&worker->threads_lock);
 606
 607         mono_trace (G_LOG_LEVEL_INFO, MONO_TRACE_THREADPOOL, "[%p] worker finishing", mono_native_thread_id_get ());
 608
 609         mono_refcount_dec (worker);
 610
 611         return 0;
 612 }
 613
 614 static gboolean
 615 worker_try_create (MonoThreadPoolWorker *worker)
 616 {
 617         MonoError error;
 618         MonoInternalThread *thread;
 619         gint64 current_ticks;
 620         gint32 now;
 621         ThreadPoolWorkerCounter counter;
 622
 623         if (mono_runtime_is_shutting_down ())
 624                 return FALSE;
 625
 626         mono_coop_mutex_lock (&worker->worker_creation_lock);
 627
 628         mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] try create worker", mono_native_thread_id_get ());
 629
 630         current_ticks = mono_100ns_ticks ();
 631         if (0 == current_ticks) {
 632                 g_warning ("failed to get 100ns ticks");
 633         } else {
 634                 now = current_ticks / (10 * 1000 * 1000);
 635                 if (worker->worker_creation_current_second != now) {
 636                         worker->worker_creation_current_second = now;
 637                         worker->worker_creation_current_count = 0;
 638                 } else {
 639                         g_assert (worker->worker_creation_current_count <= WORKER_CREATION_MAX_PER_SEC);
 640                         if (worker->worker_creation_current_count == WORKER_CREATION_MAX_PER_SEC) {
 641                                 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",
 642                                         mono_native_thread_id_get (), worker->worker_creation_current_count);
 643                                 mono_coop_mutex_unlock (&worker->worker_creation_lock);
 644                                 return FALSE;
 645                         }
 646                 }
 647         }
 648
 649         COUNTER_ATOMIC (worker, counter, {
 650                 if (counter._.working >= counter._.max_working) {
 651                         mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] try create worker, failed: maximum number of working threads reached",
 652                                 mono_native_thread_id_get ());
 653                         mono_coop_mutex_unlock (&worker->worker_creation_lock);
 654                         return FALSE;
 655                 }
 656                 counter._.starting ++;
 657         });
 658
 659         thread = mono_thread_create_internal (mono_get_root_domain (), worker_thread, mono_refcount_inc (worker), TRUE, 0, &error);
 660         if (!thread) {
 661                 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));
 662                 mono_error_cleanup (&error);
 663
 664                 COUNTER_ATOMIC (worker, counter, {
 665                         counter._.starting --;
 666                 });
 667
 668                 mono_coop_mutex_unlock (&worker->worker_creation_lock);
 669
 670                 mono_refcount_dec (worker);
 671
 672                 return FALSE;
 673         }
 674
 675         worker->worker_creation_current_count += 1;
 676
 677         mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] try create worker, created %p, now = %d count = %d",
 678                 mono_native_thread_id_get (), (gpointer) thread->tid, now, worker->worker_creation_current_count);
 679
 680         mono_coop_mutex_unlock (&worker->worker_creation_lock);
 681         return TRUE;
 682 }
 683
 684 static void monitor_ensure_running (MonoThreadPoolWorker *worker);
 685
 686 static void
 687 worker_request (MonoThreadPoolWorker *worker)
 688 {
 689         g_assert (worker);
 690
 691         if (worker->suspended)
 692                 return;
 693
 694         monitor_ensure_running (worker);
 695
 696         if (worker_try_unpark (worker)) {
 697                 mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] request worker, unparked", mono_native_thread_id_get ());
 698                 return;
 699         }
 700
 701         if (worker_try_create (worker)) {
 702                 mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] request worker, created", mono_native_thread_id_get ());
 703                 return;
 704         }
 705
 706         mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] request worker, failed", mono_native_thread_id_get ());
 707 }
 708
 709 static gboolean
 710 monitor_should_keep_running (MonoThreadPoolWorker *worker)
 711 {
 712         static gint64 last_should_keep_running = -1;
 713
 714         g_assert (worker->monitor_status == MONITOR_STATUS_WAITING_FOR_REQUEST || worker->monitor_status == MONITOR_STATUS_REQUESTED);
 715
 716         if (InterlockedExchange (&worker->monitor_status, MONITOR_STATUS_WAITING_FOR_REQUEST) == MONITOR_STATUS_WAITING_FOR_REQUEST) {
 717                 gboolean should_keep_running = TRUE, force_should_keep_running = FALSE;
 718
 719                 if (mono_runtime_is_shutting_down ()) {
 720                         should_keep_running = FALSE;
 721                 } else {
 722                         if (work_item_count (worker) == 0)
 723                                 should_keep_running = FALSE;
 724
 725                         if (!should_keep_running) {
 726                                 if (last_should_keep_running == -1 || mono_100ns_ticks () - last_should_keep_running < MONITOR_MINIMAL_LIFETIME * 1000 * 10) {
 727                                         should_keep_running = force_should_keep_running = TRUE;
 728                                 }
 729                         }
 730                 }
 731
 732                 if (should_keep_running) {
 733                         if (last_should_keep_running == -1 || !force_should_keep_running)
 734                                 last_should_keep_running = mono_100ns_ticks ();
 735                 } else {
 736                         last_should_keep_running = -1;
 737                         if (InterlockedCompareExchange (&worker->monitor_status, MONITOR_STATUS_NOT_RUNNING, MONITOR_STATUS_WAITING_FOR_REQUEST) == MONITOR_STATUS_WAITING_FOR_REQUEST)
 738                                 return FALSE;
 739                 }
 740         }
 741
 742         g_assert (worker->monitor_status == MONITOR_STATUS_WAITING_FOR_REQUEST || worker->monitor_status == MONITOR_STATUS_REQUESTED);
 743
 744         return TRUE;
 745 }
 746
 747 static gboolean
 748 monitor_sufficient_delay_since_last_dequeue (MonoThreadPoolWorker *worker)
 749 {
 750         gint64 threshold;
 751
 752         g_assert (worker);
 753
 754         if (worker->cpu_usage < CPU_USAGE_LOW) {
 755                 threshold = MONITOR_INTERVAL;
 756         } else {
 757                 ThreadPoolWorkerCounter counter;
 758                 counter = COUNTER_READ (worker);
 759                 threshold = counter._.max_working * MONITOR_INTERVAL * 2;
 760         }
 761
 762         return mono_msec_ticks () >= worker->heuristic_last_dequeue + threshold;
 763 }
 764
 765 static void hill_climbing_force_change (MonoThreadPoolWorker *worker, gint16 new_thread_count, ThreadPoolHeuristicStateTransition transition);
 766
 767 static gsize WINAPI
 768 monitor_thread (gpointer data)
 769 {
 770         MonoThreadPoolWorker *worker;
 771         MonoInternalThread *internal;
 772         guint i;
 773
 774         worker = (MonoThreadPoolWorker*) data;
 775         g_assert (worker);
 776
 777         internal = mono_thread_internal_current ();
 778         g_assert (internal);
 779
 780         mono_cpu_usage (worker->cpu_usage_state);
 781
 782         // printf ("monitor_thread: start\n");
 783
 784         mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] monitor thread, started", mono_native_thread_id_get ());
 785
 786         do {
 787                 ThreadPoolWorkerCounter counter;
 788                 gboolean limit_worker_max_reached;
 789                 gint32 interval_left = MONITOR_INTERVAL;
 790                 gint32 awake = 0; /* number of spurious awakes we tolerate before doing a round of rebalancing */
 791
 792                 g_assert (worker->monitor_status != MONITOR_STATUS_NOT_RUNNING);
 793
 794                 // counter = COUNTER_READ (worker);
 795                 // printf ("monitor_thread: starting = %d working = %d parked = %d max_working = %d\n",
 796                 //      counter._.starting, counter._.working, counter._.parked, counter._.max_working);
 797
 798                 do {
 799                         gint64 ts;
 800                         gboolean alerted = FALSE;
 801
 802                         if (mono_runtime_is_shutting_down ())
 803                                 break;
 804
 805                         ts = mono_msec_ticks ();
 806                         if (mono_thread_info_sleep (interval_left, &alerted) == 0)
 807                                 break;
 808                         interval_left -= mono_msec_ticks () - ts;
 809
 810                         g_assert (!(internal->state & ThreadState_StopRequested));
 811                         mono_thread_interruption_checkpoint ();
 812                 } while (interval_left > 0 && ++awake < 10);
 813
 814                 if (mono_runtime_is_shutting_down ())
 815                         continue;
 816
 817                 if (worker->suspended)
 818                         continue;
 819
 820                 if (work_item_count (worker) == 0)
 821                         continue;
 822
 823                 worker->cpu_usage = mono_cpu_usage (worker->cpu_usage_state);
 824
 825                 if (!monitor_sufficient_delay_since_last_dequeue (worker))
 826                         continue;
 827
 828                 limit_worker_max_reached = FALSE;
 829
 830                 COUNTER_ATOMIC (worker, counter, {
 831                         if (counter._.max_working >= worker->limit_worker_max) {
 832                                 limit_worker_max_reached = TRUE;
 833                                 break;
 834                         }
 835                         counter._.max_working ++;
 836                 });
 837
 838                 if (limit_worker_max_reached)
 839                         continue;
 840
 841                 hill_climbing_force_change (worker, counter._.max_working, TRANSITION_STARVATION);
 842
 843                 for (i = 0; i < 5; ++i) {
 844                         if (mono_runtime_is_shutting_down ())
 845                                 break;
 846
 847                         if (worker_try_unpark (worker)) {
 848                                 mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] monitor thread, unparked", mono_native_thread_id_get ());
 849                                 break;
 850                         }
 851
 852                         if (worker_try_create (worker)) {
 853                                 mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] monitor thread, created", mono_native_thread_id_get ());
 854                                 break;
 855                         }
 856                 }
 857         } while (monitor_should_keep_running (worker));
 858
 859         // printf ("monitor_thread: stop\n");
 860
 861         mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] monitor thread, finished", mono_native_thread_id_get ());
 862
 863         return 0;
 864 }
 865
 866 static void
 867 monitor_ensure_running (MonoThreadPoolWorker *worker)
 868 {
 869         MonoError error;
 870         for (;;) {
 871                 switch (worker->monitor_status) {
 872                 case MONITOR_STATUS_REQUESTED:
 873                         // printf ("monitor_thread: requested\n");
 874                         return;
 875                 case MONITOR_STATUS_WAITING_FOR_REQUEST:
 876                         // printf ("monitor_thread: waiting for request\n");
 877                         InterlockedCompareExchange (&worker->monitor_status, MONITOR_STATUS_REQUESTED, MONITOR_STATUS_WAITING_FOR_REQUEST);
 878                         break;
 879                 case MONITOR_STATUS_NOT_RUNNING:
 880                         // printf ("monitor_thread: not running\n");
 881                         if (mono_runtime_is_shutting_down ())
 882                                 return;
 883                         if (InterlockedCompareExchange (&worker->monitor_status, MONITOR_STATUS_REQUESTED, MONITOR_STATUS_NOT_RUNNING) == MONITOR_STATUS_NOT_RUNNING) {
 884                                 // printf ("monitor_thread: creating\n");
 885                                 if (!mono_thread_create_internal (mono_get_root_domain (), monitor_thread, worker, TRUE, SMALL_STACK, &error)) {
 886                                         // printf ("monitor_thread: creating failed\n");
 887                                         worker->monitor_status = MONITOR_STATUS_NOT_RUNNING;
 888                                         mono_error_cleanup (&error);
 889                                 }
 890                                 return;
 891                         }
 892                         break;
 893                 default: g_assert_not_reached ();
 894                 }
 895         }
 896 }
 897
 898 static void
 899 hill_climbing_change_thread_count (MonoThreadPoolWorker *worker, gint16 new_thread_count, ThreadPoolHeuristicStateTransition transition)
 900 {
 901         ThreadPoolHillClimbing *hc;
 902
 903         g_assert (worker);
 904
 905         hc = &worker->heuristic_hill_climbing;
 906
 907         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);
 908
 909         hc->last_thread_count = new_thread_count;
 910         hc->current_sample_interval = rand_next (&hc->random_interval_generator, hc->sample_interval_low, hc->sample_interval_high);
 911         hc->elapsed_since_last_change = 0;
 912         hc->completions_since_last_change = 0;
 913 }
 914
 915 static void
 916 hill_climbing_force_change (MonoThreadPoolWorker *worker, gint16 new_thread_count, ThreadPoolHeuristicStateTransition transition)
 917 {
 918         ThreadPoolHillClimbing *hc;
 919
 920         g_assert (worker);
 921
 922         hc = &worker->heuristic_hill_climbing;
 923
 924         if (new_thread_count != hc->last_thread_count) {
 925                 hc->current_control_setting += new_thread_count - hc->last_thread_count;
 926                 hill_climbing_change_thread_count (worker, new_thread_count, transition);
 927         }
 928 }
 929
 930 static double_complex
 931 hill_climbing_get_wave_component (MonoThreadPoolWorker *worker, gdouble *samples, guint sample_count, gdouble period)
 932 {
 933         ThreadPoolHillClimbing *hc;
 934         gdouble w, cosine, sine, coeff, q0, q1, q2;
 935         guint i;
 936
 937         g_assert (worker);
 938         g_assert (sample_count >= period);
 939         g_assert (period >= 2);
 940
 941         hc = &worker->heuristic_hill_climbing;
 942
 943         w = 2.0 * M_PI / period;
 944         cosine = cos (w);
 945         sine = sin (w);
 946         coeff = 2.0 * cosine;
 947         q0 = q1 = q2 = 0;
 948
 949         for (i = 0; i < sample_count; ++i) {
 950                 q0 = coeff * q1 - q2 + samples [(hc->total_samples - sample_count + i) % hc->samples_to_measure];
 951                 q2 = q1;
 952                 q1 = q0;
 953         }
 954
 955         return mono_double_complex_scalar_div (mono_double_complex_make (q1 - q2 * cosine, (q2 * sine)), ((gdouble)sample_count));
 956 }
 957
 958 static gint16
 959 hill_climbing_update (MonoThreadPoolWorker *worker, gint16 current_thread_count, guint32 sample_duration, gint32 completions, gint64 *adjustment_interval)
 960 {
 961         ThreadPoolHillClimbing *hc;
 962         ThreadPoolHeuristicStateTransition transition;
 963         gdouble throughput;
 964         gdouble throughput_error_estimate;
 965         gdouble confidence;
 966         gdouble move;
 967         gdouble gain;
 968         gint sample_index;
 969         gint sample_count;
 970         gint new_thread_wave_magnitude;
 971         gint new_thread_count;
 972         double_complex thread_wave_component;
 973         double_complex throughput_wave_component;
 974         double_complex ratio;
 975
 976         g_assert (worker);
 977         g_assert (adjustment_interval);
 978
 979         hc = &worker->heuristic_hill_climbing;
 980
 981         /* If someone changed the thread count without telling us, update our records accordingly. */
 982         if (current_thread_count != hc->last_thread_count)
 983                 hill_climbing_force_change (worker, current_thread_count, TRANSITION_INITIALIZING);
 984
 985         /* Update the cumulative stats for this thread count */
 986         hc->elapsed_since_last_change += sample_duration;
 987         hc->completions_since_last_change += completions;
 988
 989         /* Add in any data we've already collected about this sample */
 990         sample_duration += hc->accumulated_sample_duration;
 991         completions += hc->accumulated_completion_count;
 992
 993         /* We need to make sure we're collecting reasonably accurate data. Since we're just counting the end
 994          * of each work item, we are goinng to be missing some data about what really happened during the
 995          * sample interval. The count produced by each thread includes an initial work item that may have
 996          * started well before the start of the interval, and each thread may have been running some new
 997          * work item for some time before the end of the interval, which did not yet get counted. So
 998          * our count is going to be off by +/- threadCount workitems.
 999          *
1000          * The exception is that the thread that reported to us last time definitely wasn't running any work
1001          * at that time, and the thread that's reporting now definitely isn't running a work item now. So
1002          * we really only need to consider threadCount-1 threads.
1003          *
1004          * Thus the percent error in our count is +/- (threadCount-1)/numCompletions.
1005          *
1006          * We cannot rely on the frequency-domain analysis we'll be doing later to filter out this error, because
1007          * of the way it accumulates over time. If this sample is off by, say, 33% in the negative direction,
1008          * then the next one likely will be too. The one after that will include the sum of the completions
1009          * we missed in the previous samples, and so will be 33% positive. So every three samples we'll have
1010          * two "low" samples and one "high" sample. This will appear as periodic variation right in the frequency
1011          * range we're targeting, which will not be filtered by the frequency-domain translation. */
1012         if (hc->total_samples > 0 && ((current_thread_count - 1.0) / completions) >= hc->max_sample_error) {
1013                 /* Not accurate enough yet. Let's accumulate the data so
1014                  * far, and tell the MonoThreadPoolWorker to collect a little more. */
1015                 hc->accumulated_sample_duration = sample_duration;
1016                 hc->accumulated_completion_count = completions;
1017                 *adjustment_interval = 10;
1018                 return current_thread_count;
1019         }
1020
1021         /* We've got enouugh data for our sample; reset our accumulators for next time. */
1022         hc->accumulated_sample_duration = 0;
1023         hc->accumulated_completion_count = 0;
1024
1025         /* Add the current thread count and throughput sample to our history. */
1026         throughput = ((gdouble) completions) / sample_duration;
1027
1028         sample_index = hc->total_samples % hc->samples_to_measure;
1029         hc->samples [sample_index] = throughput;
1030         hc->thread_counts [sample_index] = current_thread_count;
1031         hc->total_samples ++;
1032
1033         /* Set up defaults for our metrics. */
1034         thread_wave_component = mono_double_complex_make(0, 0);
1035         throughput_wave_component = mono_double_complex_make(0, 0);
1036         throughput_error_estimate = 0;
1037         ratio = mono_double_complex_make(0, 0);
1038         confidence = 0;
1039
1040         transition = TRANSITION_WARMUP;
1041
1042         /* How many samples will we use? It must be at least the three wave periods we're looking for, and it must also
1043          * be a whole multiple of the primary wave's period; otherwise the frequency we're looking for will fall between
1044          * two frequency bands in the Fourier analysis, and we won't be able to measure it accurately. */
1045         sample_count = ((gint) MIN (hc->total_samples - 1, hc->samples_to_measure) / hc->wave_period) * hc->wave_period;
1046
1047         if (sample_count > hc->wave_period) {
1048                 guint i;
1049                 gdouble average_throughput;
1050                 gdouble average_thread_count;
1051                 gdouble sample_sum = 0;
1052                 gdouble thread_sum = 0;
1053
1054                 /* Average the throughput and thread count samples, so we can scale the wave magnitudes later. */
1055                 for (i = 0; i < sample_count; ++i) {
1056                         guint j = (hc->total_samples - sample_count + i) % hc->samples_to_measure;
1057                         sample_sum += hc->samples [j];
1058                         thread_sum += hc->thread_counts [j];
1059                 }
1060
1061                 average_throughput = sample_sum / sample_count;
1062                 average_thread_count = thread_sum / sample_count;
1063
1064                 if (average_throughput > 0 && average_thread_count > 0) {
1065                         gdouble noise_for_confidence, adjacent_period_1, adjacent_period_2;
1066
1067                         /* Calculate the periods of the adjacent frequency bands we'll be using to
1068                          * measure noise levels. We want the two adjacent Fourier frequency bands. */
1069                         adjacent_period_1 = sample_count / (((gdouble) sample_count) / ((gdouble) hc->wave_period) + 1);
1070                         adjacent_period_2 = sample_count / (((gdouble) sample_count) / ((gdouble) hc->wave_period) - 1);
1071
1072                         /* Get the the three different frequency components of the throughput (scaled by average
1073                          * throughput). Our "error" estimate (the amount of noise that might be present in the
1074                          * frequency band we're really interested in) is the average of the adjacent bands. */
1075                         throughput_wave_component = mono_double_complex_scalar_div (hill_climbing_get_wave_component (worker, hc->samples, sample_count, hc->wave_period), average_throughput);
1076                         throughput_error_estimate = cabs (mono_double_complex_scalar_div (hill_climbing_get_wave_component (worker, hc->samples, sample_count, adjacent_period_1), average_throughput));
1077
1078                         if (adjacent_period_2 <= sample_count) {
1079                                 throughput_error_estimate = MAX (throughput_error_estimate, cabs (mono_double_complex_scalar_div (hill_climbing_get_wave_component (
1080                                         worker, hc->samples, sample_count, adjacent_period_2), average_throughput)));
1081                         }
1082
1083                         /* Do the same for the thread counts, so we have something to compare to. We don't
1084                          * measure thread count noise, because there is none; these are exact measurements. */
1085                         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);
1086
1087                         /* Update our moving average of the throughput noise. We'll use this
1088                          * later as feedback to determine the new size of the thread wave. */
1089                         if (hc->average_throughput_noise == 0) {
1090                                 hc->average_throughput_noise = throughput_error_estimate;
1091                         } else {
1092                                 hc->average_throughput_noise = (hc->throughput_error_smoothing_factor * throughput_error_estimate)
1093                                         + ((1.0 + hc->throughput_error_smoothing_factor) * hc->average_throughput_noise);
1094                         }
1095
1096                         if (cabs (thread_wave_component) > 0) {
1097                                 /* Adjust the throughput wave so it's centered around the target wave,
1098                                  * and then calculate the adjusted throughput/thread ratio. */
1099                                 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);
1100                                 transition = TRANSITION_CLIMBING_MOVE;
1101                         } else {
1102                                 ratio = mono_double_complex_make (0, 0);
1103                                 transition = TRANSITION_STABILIZING;
1104                         }
1105
1106                         noise_for_confidence = MAX (hc->average_throughput_noise, throughput_error_estimate);
1107                         if (noise_for_confidence > 0) {
1108                                 confidence = cabs (thread_wave_component) / noise_for_confidence / hc->target_signal_to_noise_ratio;
1109                         } else {
1110                                 /* there is no noise! */
1111                                 confidence = 1.0;
1112                         }
1113                 }
1114         }
1115
1116         /* We use just the real part of the complex ratio we just calculated. If the throughput signal
1117          * is exactly in phase with the thread signal, this will be the same as taking the magnitude of
1118          * the complex move and moving that far up. If they're 180 degrees out of phase, we'll move
1119          * backward (because this indicates that our changes are having the opposite of the intended effect).
1120          * If they're 90 degrees out of phase, we won't move at all, because we can't tell wether we're
1121          * having a negative or positive effect on throughput. */
1122         move = creal (ratio);
1123         move = CLAMP (move, -1.0, 1.0);
1124
1125         /* Apply our confidence multiplier. */
1126         move *= CLAMP (confidence, -1.0, 1.0);
1127
1128         /* Now apply non-linear gain, such that values around zero are attenuated, while higher values
1129          * are enhanced. This allows us to move quickly if we're far away from the target, but more slowly
1130         * if we're getting close, giving us rapid ramp-up without wild oscillations around the target. */
1131         gain = hc->max_change_per_second * sample_duration;
1132         move = pow (fabs (move), hc->gain_exponent) * (move >= 0.0 ? 1 : -1) * gain;
1133         move = MIN (move, hc->max_change_per_sample);
1134
1135         /* If the result was positive, and CPU is > 95%, refuse the move. */
1136         if (move > 0.0 && worker->cpu_usage > CPU_USAGE_HIGH)
1137                 move = 0.0;
1138
1139         /* Apply the move to our control setting. */
1140         hc->current_control_setting += move;
1141
1142         /* Calculate the new thread wave magnitude, which is based on the moving average we've been keeping of the
1143          * throughput error.  This average starts at zero, so we'll start with a nice safe little wave at first. */
1144         new_thread_wave_magnitude = (gint)(0.5 + (hc->current_control_setting * hc->average_throughput_noise
1145                 * hc->target_signal_to_noise_ratio * hc->thread_magnitude_multiplier * 2.0));
1146         new_thread_wave_magnitude = CLAMP (new_thread_wave_magnitude, 1, hc->max_thread_wave_magnitude);
1147
1148         /* Make sure our control setting is within the MonoThreadPoolWorker's limits. */
1149         hc->current_control_setting = CLAMP (hc->current_control_setting, worker->limit_worker_min, worker->limit_worker_max - new_thread_wave_magnitude);
1150
1151         /* Calculate the new thread count (control setting + square wave). */
1152         new_thread_count = (gint)(hc->current_control_setting + new_thread_wave_magnitude * ((hc->total_samples / (hc->wave_period / 2)) % 2));
1153
1154         /* Make sure the new thread count doesn't exceed the MonoThreadPoolWorker's limits. */
1155         new_thread_count = CLAMP (new_thread_count, worker->limit_worker_min, worker->limit_worker_max);
1156
1157         if (new_thread_count != current_thread_count)
1158                 hill_climbing_change_thread_count (worker, new_thread_count, transition);
1159
1160         if (creal (ratio) < 0.0 && new_thread_count == worker->limit_worker_min)
1161                 *adjustment_interval = (gint)(0.5 + hc->current_sample_interval * (10.0 * MAX (-1.0 * creal (ratio), 1.0)));
1162         else
1163                 *adjustment_interval = hc->current_sample_interval;
1164
1165         return new_thread_count;
1166 }
1167
1168 static gboolean
1169 heuristic_should_adjust (MonoThreadPoolWorker *worker)
1170 {
1171         if (worker->heuristic_last_dequeue > worker->heuristic_last_adjustment + worker->heuristic_adjustment_interval) {
1172                 ThreadPoolWorkerCounter counter;
1173                 counter = COUNTER_READ (worker);
1174                 if (counter._.working <= counter._.max_working)
1175                         return TRUE;
1176         }
1177
1178         return FALSE;
1179 }
1180
1181 static void
1182 heuristic_adjust (MonoThreadPoolWorker *worker)
1183 {
1184         if (mono_coop_mutex_trylock (&worker->heuristic_lock) == 0) {
1185                 gint32 completions = InterlockedExchange (&worker->heuristic_completions, 0);
1186                 gint64 sample_end = mono_msec_ticks ();
1187                 gint64 sample_duration = sample_end - worker->heuristic_sample_start;
1188
1189                 if (sample_duration >= worker->heuristic_adjustment_interval / 2) {
1190                         ThreadPoolWorkerCounter counter;
1191                         gint16 new_thread_count;
1192
1193                         counter = COUNTER_READ (worker);
1194                         new_thread_count = hill_climbing_update (worker, counter._.max_working, sample_duration, completions, &worker->heuristic_adjustment_interval);
1195
1196                         COUNTER_ATOMIC (worker, counter, {
1197                                 counter._.max_working = new_thread_count;
1198                         });
1199
1200                         if (new_thread_count > counter._.max_working)
1201                                 worker_request (worker);
1202
1203                         worker->heuristic_sample_start = sample_end;
1204                         worker->heuristic_last_adjustment = mono_msec_ticks ();
1205                 }
1206
1207                 mono_coop_mutex_unlock (&worker->heuristic_lock);
1208         }
1209 }
1210
1211 static void
1212 heuristic_notify_work_completed (MonoThreadPoolWorker *worker)
1213 {
1214         g_assert (worker);
1215
1216         InterlockedIncrement (&worker->heuristic_completions);
1217         worker->heuristic_last_dequeue = mono_msec_ticks ();
1218
1219         if (heuristic_should_adjust (worker))
1220                 heuristic_adjust (worker);
1221 }
1222
1223 gboolean
1224 mono_threadpool_worker_notify_completed (MonoThreadPoolWorker *worker)
1225 {
1226         ThreadPoolWorkerCounter counter;
1227
1228         heuristic_notify_work_completed (worker);
1229
1230         counter = COUNTER_READ (worker);
1231         return counter._.working <= counter._.max_working;
1232 }
1233
1234 gint32
1235 mono_threadpool_worker_get_min (MonoThreadPoolWorker *worker)
1236 {
1237         return worker->limit_worker_min;
1238 }
1239
1240 gboolean
1241 mono_threadpool_worker_set_min (MonoThreadPoolWorker *worker, gint32 value)
1242 {
1243         if (value <= 0 || value > worker->limit_worker_max)
1244                 return FALSE;
1245
1246         worker->limit_worker_min = value;
1247         return TRUE;
1248 }
1249
1250 gint32
1251 mono_threadpool_worker_get_max (MonoThreadPoolWorker *worker)
1252 {
1253         return worker->limit_worker_max;
1254 }
1255
1256 gboolean
1257 mono_threadpool_worker_set_max (MonoThreadPoolWorker *worker, gint32 value)
1258 {
1259         gint32 cpu_count = mono_cpu_count ();
1260
1261         if (value < worker->limit_worker_min || value < cpu_count)
1262                 return FALSE;
1263
1264         worker->limit_worker_max = value;
1265         return TRUE;
1266 }
1267
1268 void
1269 mono_threadpool_worker_set_suspended (MonoThreadPoolWorker *worker, gboolean suspended)
1270 {
1271         worker->suspended = suspended;
1272         if (!suspended)
1273                 worker_request (worker);
1274 }