/**
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* \file
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* native threadpool worker
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*
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* Author:
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* Ludovic Henry (ludovic.henry@xamarin.com)
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*
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* Licensed under the MIT license. See LICENSE file in the project root for full license information.
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*/
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#include <stdlib.h>
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#define _USE_MATH_DEFINES // needed by MSVC to define math constants
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#include <math.h>
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#include <config.h>
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#include <glib.h>
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#include <mono/metadata/class-internals.h>
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#include <mono/metadata/exception.h>
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#include <mono/metadata/gc-internals.h>
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#include <mono/metadata/object.h>
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#include <mono/metadata/object-internals.h>
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#include <mono/metadata/threadpool.h>
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#include <mono/metadata/threadpool-worker.h>
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#include <mono/metadata/threadpool-io.h>
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#include <mono/metadata/w32event.h>
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#include <mono/utils/atomic.h>
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#include <mono/utils/mono-compiler.h>
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#include <mono/utils/mono-complex.h>
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#include <mono/utils/mono-logger.h>
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#include <mono/utils/mono-logger-internals.h>
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#include <mono/utils/mono-proclib.h>
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#include <mono/utils/mono-threads.h>
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#include <mono/utils/mono-time.h>
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#include <mono/utils/mono-rand.h>
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#include <mono/utils/refcount.h>
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#include <mono/utils/w32api.h>
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#define CPU_USAGE_LOW 80
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#define CPU_USAGE_HIGH 95
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#define MONITOR_INTERVAL 500 // ms
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#define MONITOR_MINIMAL_LIFETIME 60 * 1000 // ms
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#define WORKER_CREATION_MAX_PER_SEC 10
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/* The exponent to apply to the gain. 1.0 means to use linear gain,
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* higher values will enhance large moves and damp small ones.
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* default: 2.0 */
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#define HILL_CLIMBING_GAIN_EXPONENT 2.0
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/* The 'cost' of a thread. 0 means drive for increased throughput regardless
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* of thread count, higher values bias more against higher thread counts.
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* default: 0.15 */
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#define HILL_CLIMBING_BIAS 0.15
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#define HILL_CLIMBING_WAVE_PERIOD 4
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#define HILL_CLIMBING_MAX_WAVE_MAGNITUDE 20
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#define HILL_CLIMBING_WAVE_MAGNITUDE_MULTIPLIER 1.0
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#define HILL_CLIMBING_WAVE_HISTORY_SIZE 8
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#define HILL_CLIMBING_TARGET_SIGNAL_TO_NOISE_RATIO 3.0
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#define HILL_CLIMBING_MAX_CHANGE_PER_SECOND 4
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#define HILL_CLIMBING_MAX_CHANGE_PER_SAMPLE 20
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#define HILL_CLIMBING_SAMPLE_INTERVAL_LOW 10
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#define HILL_CLIMBING_SAMPLE_INTERVAL_HIGH 200
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#define HILL_CLIMBING_ERROR_SMOOTHING_FACTOR 0.01
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#define HILL_CLIMBING_MAX_SAMPLE_ERROR_PERCENT 0.15
|
|
typedef enum {
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TRANSITION_WARMUP,
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TRANSITION_INITIALIZING,
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TRANSITION_RANDOM_MOVE,
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TRANSITION_CLIMBING_MOVE,
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TRANSITION_CHANGE_POINT,
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TRANSITION_STABILIZING,
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TRANSITION_STARVATION,
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TRANSITION_THREAD_TIMED_OUT,
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TRANSITION_UNDEFINED,
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} ThreadPoolHeuristicStateTransition;
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|
typedef struct {
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gint32 wave_period;
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gint32 samples_to_measure;
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gdouble target_throughput_ratio;
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gdouble target_signal_to_noise_ratio;
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gdouble max_change_per_second;
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gdouble max_change_per_sample;
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gint32 max_thread_wave_magnitude;
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gint32 sample_interval_low;
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gdouble thread_magnitude_multiplier;
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gint32 sample_interval_high;
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gdouble throughput_error_smoothing_factor;
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gdouble gain_exponent;
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gdouble max_sample_error;
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gdouble current_control_setting;
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gint64 total_samples;
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gint16 last_thread_count;
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gdouble elapsed_since_last_change;
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gdouble completions_since_last_change;
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gdouble average_throughput_noise;
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gdouble *samples;
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gdouble *thread_counts;
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guint32 current_sample_interval;
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gpointer random_interval_generator;
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|
gint32 accumulated_completion_count;
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gdouble accumulated_sample_duration;
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} ThreadPoolHillClimbing;
|
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typedef union {
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struct {
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gint16 max_working; /* determined by heuristic */
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gint16 starting; /* starting, but not yet in worker_thread */
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gint16 working; /* executing worker_thread */
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gint16 parked; /* parked */
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} _;
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gint64 as_gint64;
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} ThreadPoolWorkerCounter
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#ifdef __GNUC__
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__attribute__((aligned(64)))
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#endif
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;
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typedef struct {
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MonoRefCount ref;
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MonoThreadPoolWorkerCallback callback;
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ThreadPoolWorkerCounter counters;
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MonoCoopMutex parked_threads_lock;
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gint32 parked_threads_count;
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MonoCoopCond parked_threads_cond;
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volatile gint32 work_items_count;
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guint32 worker_creation_current_second;
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guint32 worker_creation_current_count;
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MonoCoopMutex worker_creation_lock;
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gint32 heuristic_completions;
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gint64 heuristic_sample_start;
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gint64 heuristic_last_dequeue; // ms
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gint64 heuristic_last_adjustment; // ms
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gint64 heuristic_adjustment_interval; // ms
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ThreadPoolHillClimbing heuristic_hill_climbing;
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MonoCoopMutex heuristic_lock;
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gint32 limit_worker_min;
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gint32 limit_worker_max;
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MonoCpuUsageState *cpu_usage_state;
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gint32 cpu_usage;
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/* suspended by the debugger */
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gboolean suspended;
|
|
gint32 monitor_status;
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} ThreadPoolWorker;
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enum {
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MONITOR_STATUS_REQUESTED,
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MONITOR_STATUS_WAITING_FOR_REQUEST,
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MONITOR_STATUS_NOT_RUNNING,
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};
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|
static ThreadPoolWorker worker;
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#define COUNTER_CHECK(counter) \
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do { \
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g_assert (counter._.max_working > 0); \
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g_assert (counter._.starting >= 0); \
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g_assert (counter._.working >= 0); \
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} while (0)
|
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#define COUNTER_ATOMIC(var,block) \
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do { \
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ThreadPoolWorkerCounter __old; \
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do { \
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__old = COUNTER_READ (); \
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(var) = __old; \
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{ block; } \
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COUNTER_CHECK (var); \
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} while (mono_atomic_cas_i64 (&worker.counters.as_gint64, (var).as_gint64, __old.as_gint64) != __old.as_gint64); \
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} while (0)
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static inline ThreadPoolWorkerCounter
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COUNTER_READ (void)
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{
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ThreadPoolWorkerCounter counter;
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counter.as_gint64 = mono_atomic_load_i64 (&worker.counters.as_gint64);
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return counter;
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}
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static gpointer
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rand_create (void)
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{
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mono_rand_open ();
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return mono_rand_init (NULL, 0);
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}
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static guint32
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rand_next (gpointer *handle, guint32 min, guint32 max)
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{
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MonoError error;
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guint32 val;
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mono_rand_try_get_uint32 (handle, &val, min, max, &error);
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// FIXME handle error
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mono_error_assert_ok (&error);
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return val;
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}
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static void
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destroy (gpointer data)
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{
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mono_coop_mutex_destroy (&worker.parked_threads_lock);
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mono_coop_cond_destroy (&worker.parked_threads_cond);
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mono_coop_mutex_destroy (&worker.worker_creation_lock);
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mono_coop_mutex_destroy (&worker.heuristic_lock);
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g_free (worker.cpu_usage_state);
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}
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void
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mono_threadpool_worker_init (MonoThreadPoolWorkerCallback callback)
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{
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ThreadPoolHillClimbing *hc;
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const char *threads_per_cpu_env;
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gint threads_per_cpu;
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gint threads_count;
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mono_refcount_init (&worker, destroy);
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worker.callback = callback;
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mono_coop_mutex_init (&worker.parked_threads_lock);
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worker.parked_threads_count = 0;
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mono_coop_cond_init (&worker.parked_threads_cond);
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worker.worker_creation_current_second = -1;
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mono_coop_mutex_init (&worker.worker_creation_lock);
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worker.heuristic_adjustment_interval = 10;
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mono_coop_mutex_init (&worker.heuristic_lock);
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mono_rand_open ();
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hc = &worker.heuristic_hill_climbing;
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hc->wave_period = HILL_CLIMBING_WAVE_PERIOD;
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hc->max_thread_wave_magnitude = HILL_CLIMBING_MAX_WAVE_MAGNITUDE;
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hc->thread_magnitude_multiplier = (gdouble) HILL_CLIMBING_WAVE_MAGNITUDE_MULTIPLIER;
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hc->samples_to_measure = hc->wave_period * HILL_CLIMBING_WAVE_HISTORY_SIZE;
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hc->target_throughput_ratio = (gdouble) HILL_CLIMBING_BIAS;
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hc->target_signal_to_noise_ratio = (gdouble) HILL_CLIMBING_TARGET_SIGNAL_TO_NOISE_RATIO;
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hc->max_change_per_second = (gdouble) HILL_CLIMBING_MAX_CHANGE_PER_SECOND;
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hc->max_change_per_sample = (gdouble) HILL_CLIMBING_MAX_CHANGE_PER_SAMPLE;
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hc->sample_interval_low = HILL_CLIMBING_SAMPLE_INTERVAL_LOW;
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hc->sample_interval_high = HILL_CLIMBING_SAMPLE_INTERVAL_HIGH;
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hc->throughput_error_smoothing_factor = (gdouble) HILL_CLIMBING_ERROR_SMOOTHING_FACTOR;
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hc->gain_exponent = (gdouble) HILL_CLIMBING_GAIN_EXPONENT;
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hc->max_sample_error = (gdouble) HILL_CLIMBING_MAX_SAMPLE_ERROR_PERCENT;
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hc->current_control_setting = 0;
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hc->total_samples = 0;
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hc->last_thread_count = 0;
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hc->average_throughput_noise = 0;
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hc->elapsed_since_last_change = 0;
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hc->accumulated_completion_count = 0;
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hc->accumulated_sample_duration = 0;
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hc->samples = g_new0 (gdouble, hc->samples_to_measure);
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hc->thread_counts = g_new0 (gdouble, hc->samples_to_measure);
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hc->random_interval_generator = rand_create ();
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hc->current_sample_interval = rand_next (&hc->random_interval_generator, hc->sample_interval_low, hc->sample_interval_high);
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if (!(threads_per_cpu_env = g_getenv ("MONO_THREADS_PER_CPU")))
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threads_per_cpu = 1;
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else
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threads_per_cpu = CLAMP (atoi (threads_per_cpu_env), 1, 50);
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threads_count = mono_cpu_count () * threads_per_cpu;
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worker.limit_worker_min = threads_count;
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#if defined (HOST_ANDROID) || defined (HOST_IOS)
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worker.limit_worker_max = CLAMP (threads_count * 100, MIN (threads_count, 200), MAX (threads_count, 200));
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#else
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worker.limit_worker_max = threads_count * 100;
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#endif
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worker.counters._.max_working = worker.limit_worker_min;
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worker.cpu_usage_state = g_new0 (MonoCpuUsageState, 1);
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worker.suspended = FALSE;
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worker.monitor_status = MONITOR_STATUS_NOT_RUNNING;
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}
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void
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mono_threadpool_worker_cleanup (void)
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{
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mono_refcount_dec (&worker);
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}
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static void
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work_item_push (void)
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{
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gint32 old, new;
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do {
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old = mono_atomic_load_i32 (&worker.work_items_count);
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g_assert (old >= 0);
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new = old + 1;
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} while (mono_atomic_cas_i32 (&worker.work_items_count, new, old) != old);
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}
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static gboolean
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work_item_try_pop (void)
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{
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gint32 old, new;
|
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do {
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old = mono_atomic_load_i32 (&worker.work_items_count);
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g_assert (old >= 0);
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if (old == 0)
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return FALSE;
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new = old - 1;
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} while (mono_atomic_cas_i32 (&worker.work_items_count, new, old) != old);
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return TRUE;
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}
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static gint32
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work_item_count (void)
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{
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return mono_atomic_load_i32 (&worker.work_items_count);
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}
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static void worker_request (void);
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void
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mono_threadpool_worker_request (void)
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{
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if (!mono_refcount_tryinc (&worker))
|
return;
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|
work_item_push ();
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worker_request ();
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|
mono_refcount_dec (&worker);
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}
|
|
static void
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worker_wait_interrupt (gpointer unused)
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{
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/* If the runtime is not shutting down, we are not using this mechanism to wake up a unparked thread, and if the
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* runtime is shutting down, then we need to wake up ALL the threads.
|
* It might be a bit wasteful, but I witnessed shutdown hang where the main thread would abort and then wait for all
|
* background threads to exit (see mono_thread_manage). This would go wrong because not all threadpool threads would
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* be unparked. It would end up getting unstucked because of the timeout, but that would delay shutdown by 5-60s. */
|
if (!mono_runtime_is_shutting_down ())
|
return;
|
|
if (!mono_refcount_tryinc (&worker))
|
return;
|
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mono_coop_mutex_lock (&worker.parked_threads_lock);
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mono_coop_cond_broadcast (&worker.parked_threads_cond);
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mono_coop_mutex_unlock (&worker.parked_threads_lock);
|
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mono_refcount_dec (&worker);
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}
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/* return TRUE if timeout, FALSE otherwise (worker unpark or interrupt) */
|
static gboolean
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worker_park (void)
|
{
|
gboolean timeout = FALSE;
|
gboolean interrupted = FALSE;
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mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] worker parking",
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GUINT_TO_POINTER (MONO_NATIVE_THREAD_ID_TO_UINT (mono_native_thread_id_get ())));
|
|
mono_coop_mutex_lock (&worker.parked_threads_lock);
|
|
if (!mono_runtime_is_shutting_down ()) {
|
static gpointer rand_handle = NULL;
|
MonoInternalThread *thread;
|
ThreadPoolWorkerCounter counter;
|
|
if (!rand_handle)
|
rand_handle = rand_create ();
|
g_assert (rand_handle);
|
|
thread = mono_thread_internal_current ();
|
g_assert (thread);
|
|
COUNTER_ATOMIC (counter, {
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counter._.working --;
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counter._.parked ++;
|
});
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|
worker.parked_threads_count += 1;
|
|
mono_thread_info_install_interrupt (worker_wait_interrupt, NULL, &interrupted);
|
if (interrupted)
|
goto done;
|
|
if (mono_coop_cond_timedwait (&worker.parked_threads_cond, &worker.parked_threads_lock, rand_next (&rand_handle, 5 * 1000, 60 * 1000)) != 0)
|
timeout = TRUE;
|
|
mono_thread_info_uninstall_interrupt (&interrupted);
|
|
done:
|
worker.parked_threads_count -= 1;
|
|
COUNTER_ATOMIC (counter, {
|
counter._.working ++;
|
counter._.parked --;
|
});
|
}
|
|
mono_coop_mutex_unlock (&worker.parked_threads_lock);
|
|
mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] worker unparking, timeout? %s interrupted? %s",
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GUINT_TO_POINTER (MONO_NATIVE_THREAD_ID_TO_UINT (mono_native_thread_id_get ())), timeout ? "yes" : "no", interrupted ? "yes" : "no");
|
|
return timeout;
|
}
|
|
static gboolean
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worker_try_unpark (void)
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{
|
gboolean res = FALSE;
|
|
mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] try unpark worker",
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GUINT_TO_POINTER (MONO_NATIVE_THREAD_ID_TO_UINT (mono_native_thread_id_get ())));
|
|
mono_coop_mutex_lock (&worker.parked_threads_lock);
|
if (worker.parked_threads_count > 0) {
|
mono_coop_cond_signal (&worker.parked_threads_cond);
|
res = TRUE;
|
}
|
mono_coop_mutex_unlock (&worker.parked_threads_lock);
|
|
mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] try unpark worker, success? %s",
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GUINT_TO_POINTER (MONO_NATIVE_THREAD_ID_TO_UINT (mono_native_thread_id_get ())), res ? "yes" : "no");
|
|
return res;
|
}
|
|
static gsize WINAPI
|
worker_thread (gpointer unused)
|
{
|
MonoInternalThread *thread;
|
ThreadPoolWorkerCounter counter;
|
|
mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] worker starting",
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GUINT_TO_POINTER (MONO_NATIVE_THREAD_ID_TO_UINT (mono_native_thread_id_get ())));
|
|
if (!mono_refcount_tryinc (&worker))
|
return 0;
|
|
COUNTER_ATOMIC (counter, {
|
counter._.starting --;
|
counter._.working ++;
|
});
|
|
thread = mono_thread_internal_current ();
|
g_assert (thread);
|
|
while (!mono_runtime_is_shutting_down ()) {
|
if (mono_thread_interruption_checkpoint ())
|
continue;
|
|
if (!work_item_try_pop ()) {
|
gboolean timeout;
|
|
timeout = worker_park ();
|
if (timeout)
|
break;
|
|
continue;
|
}
|
|
mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] worker executing",
|
GUINT_TO_POINTER (MONO_NATIVE_THREAD_ID_TO_UINT (mono_native_thread_id_get ())));
|
|
worker.callback ();
|
}
|
|
COUNTER_ATOMIC (counter, {
|
counter._.working --;
|
});
|
|
mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] worker finishing",
|
GUINT_TO_POINTER (MONO_NATIVE_THREAD_ID_TO_UINT (mono_native_thread_id_get ())));
|
|
mono_refcount_dec (&worker);
|
|
return 0;
|
}
|
|
static gboolean
|
worker_try_create (void)
|
{
|
MonoError error;
|
MonoInternalThread *thread;
|
gint64 current_ticks;
|
gint32 now;
|
ThreadPoolWorkerCounter counter;
|
|
if (mono_runtime_is_shutting_down ())
|
return FALSE;
|
|
mono_coop_mutex_lock (&worker.worker_creation_lock);
|
|
mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] try create worker",
|
GUINT_TO_POINTER (MONO_NATIVE_THREAD_ID_TO_UINT (mono_native_thread_id_get ())));
|
|
current_ticks = mono_100ns_ticks ();
|
if (0 == current_ticks) {
|
g_warning ("failed to get 100ns ticks");
|
} else {
|
now = current_ticks / (10 * 1000 * 1000);
|
if (worker.worker_creation_current_second != now) {
|
worker.worker_creation_current_second = now;
|
worker.worker_creation_current_count = 0;
|
} else {
|
g_assert (worker.worker_creation_current_count <= WORKER_CREATION_MAX_PER_SEC);
|
if (worker.worker_creation_current_count == WORKER_CREATION_MAX_PER_SEC) {
|
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",
|
GUINT_TO_POINTER (MONO_NATIVE_THREAD_ID_TO_UINT (mono_native_thread_id_get ())), worker.worker_creation_current_count);
|
mono_coop_mutex_unlock (&worker.worker_creation_lock);
|
return FALSE;
|
}
|
}
|
}
|
|
COUNTER_ATOMIC (counter, {
|
if (counter._.working >= counter._.max_working) {
|
mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] try create worker, failed: maximum number of working threads reached",
|
GUINT_TO_POINTER (MONO_NATIVE_THREAD_ID_TO_UINT (mono_native_thread_id_get ())));
|
mono_coop_mutex_unlock (&worker.worker_creation_lock);
|
return FALSE;
|
}
|
counter._.starting ++;
|
});
|
|
thread = mono_thread_create_internal (mono_get_root_domain (), worker_thread, NULL, MONO_THREAD_CREATE_FLAGS_THREADPOOL, &error);
|
if (!thread) {
|
mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] try create worker, failed: could not create thread due to %s",
|
GUINT_TO_POINTER (MONO_NATIVE_THREAD_ID_TO_UINT (mono_native_thread_id_get ())), mono_error_get_message (&error));
|
mono_error_cleanup (&error);
|
|
COUNTER_ATOMIC (counter, {
|
counter._.starting --;
|
});
|
|
mono_coop_mutex_unlock (&worker.worker_creation_lock);
|
|
return FALSE;
|
}
|
|
worker.worker_creation_current_count += 1;
|
|
mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] try create worker, created %p, now = %d count = %d",
|
GUINT_TO_POINTER (MONO_NATIVE_THREAD_ID_TO_UINT (mono_native_thread_id_get ())), (gpointer) thread->tid, now, worker.worker_creation_current_count);
|
|
mono_coop_mutex_unlock (&worker.worker_creation_lock);
|
return TRUE;
|
}
|
|
static void monitor_ensure_running (void);
|
|
static void
|
worker_request (void)
|
{
|
if (worker.suspended)
|
return;
|
|
monitor_ensure_running ();
|
|
if (worker_try_unpark ()) {
|
mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] request worker, unparked",
|
GUINT_TO_POINTER (MONO_NATIVE_THREAD_ID_TO_UINT (mono_native_thread_id_get ())));
|
return;
|
}
|
|
if (worker_try_create ()) {
|
mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] request worker, created",
|
GUINT_TO_POINTER (MONO_NATIVE_THREAD_ID_TO_UINT (mono_native_thread_id_get ())));
|
return;
|
}
|
|
mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] request worker, failed",
|
GUINT_TO_POINTER (MONO_NATIVE_THREAD_ID_TO_UINT (mono_native_thread_id_get ())));
|
}
|
|
static gboolean
|
monitor_should_keep_running (void)
|
{
|
static gint64 last_should_keep_running = -1;
|
|
g_assert (worker.monitor_status == MONITOR_STATUS_WAITING_FOR_REQUEST || worker.monitor_status == MONITOR_STATUS_REQUESTED);
|
|
if (mono_atomic_xchg_i32 (&worker.monitor_status, MONITOR_STATUS_WAITING_FOR_REQUEST) == MONITOR_STATUS_WAITING_FOR_REQUEST) {
|
gboolean should_keep_running = TRUE, force_should_keep_running = FALSE;
|
|
if (mono_runtime_is_shutting_down ()) {
|
should_keep_running = FALSE;
|
} else {
|
if (work_item_count () == 0)
|
should_keep_running = FALSE;
|
|
if (!should_keep_running) {
|
if (last_should_keep_running == -1 || mono_100ns_ticks () - last_should_keep_running < MONITOR_MINIMAL_LIFETIME * 1000 * 10) {
|
should_keep_running = force_should_keep_running = TRUE;
|
}
|
}
|
}
|
|
if (should_keep_running) {
|
if (last_should_keep_running == -1 || !force_should_keep_running)
|
last_should_keep_running = mono_100ns_ticks ();
|
} else {
|
last_should_keep_running = -1;
|
if (mono_atomic_cas_i32 (&worker.monitor_status, MONITOR_STATUS_NOT_RUNNING, MONITOR_STATUS_WAITING_FOR_REQUEST) == MONITOR_STATUS_WAITING_FOR_REQUEST)
|
return FALSE;
|
}
|
}
|
|
g_assert (worker.monitor_status == MONITOR_STATUS_WAITING_FOR_REQUEST || worker.monitor_status == MONITOR_STATUS_REQUESTED);
|
|
return TRUE;
|
}
|
|
static gboolean
|
monitor_sufficient_delay_since_last_dequeue (void)
|
{
|
gint64 threshold;
|
|
if (worker.cpu_usage < CPU_USAGE_LOW) {
|
threshold = MONITOR_INTERVAL;
|
} else {
|
ThreadPoolWorkerCounter counter;
|
counter = COUNTER_READ ();
|
threshold = counter._.max_working * MONITOR_INTERVAL * 2;
|
}
|
|
return mono_msec_ticks () >= worker.heuristic_last_dequeue + threshold;
|
}
|
|
static void hill_climbing_force_change (gint16 new_thread_count, ThreadPoolHeuristicStateTransition transition);
|
|
static gsize WINAPI
|
monitor_thread (gpointer unused)
|
{
|
MonoInternalThread *internal;
|
guint i;
|
|
if (!mono_refcount_tryinc (&worker))
|
return 0;
|
|
internal = mono_thread_internal_current ();
|
g_assert (internal);
|
|
mono_cpu_usage (worker.cpu_usage_state);
|
|
// printf ("monitor_thread: start\n");
|
|
mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] monitor thread, started",
|
GUINT_TO_POINTER (MONO_NATIVE_THREAD_ID_TO_UINT (mono_native_thread_id_get ())));
|
|
do {
|
ThreadPoolWorkerCounter counter;
|
gboolean limit_worker_max_reached;
|
gint32 interval_left = MONITOR_INTERVAL;
|
gint32 awake = 0; /* number of spurious awakes we tolerate before doing a round of rebalancing */
|
|
g_assert (worker.monitor_status != MONITOR_STATUS_NOT_RUNNING);
|
|
// counter = COUNTER_READ ();
|
// printf ("monitor_thread: starting = %d working = %d parked = %d max_working = %d\n",
|
// counter._.starting, counter._.working, counter._.parked, counter._.max_working);
|
|
do {
|
gint64 ts;
|
gboolean alerted = FALSE;
|
|
if (mono_runtime_is_shutting_down ())
|
break;
|
|
ts = mono_msec_ticks ();
|
if (mono_thread_info_sleep (interval_left, &alerted) == 0)
|
break;
|
interval_left -= mono_msec_ticks () - ts;
|
|
mono_thread_interruption_checkpoint ();
|
} while (interval_left > 0 && ++awake < 10);
|
|
if (mono_runtime_is_shutting_down ())
|
continue;
|
|
if (worker.suspended)
|
continue;
|
|
if (work_item_count () == 0)
|
continue;
|
|
worker.cpu_usage = mono_cpu_usage (worker.cpu_usage_state);
|
|
if (!monitor_sufficient_delay_since_last_dequeue ())
|
continue;
|
|
limit_worker_max_reached = FALSE;
|
|
COUNTER_ATOMIC (counter, {
|
if (counter._.max_working >= worker.limit_worker_max) {
|
limit_worker_max_reached = TRUE;
|
break;
|
}
|
counter._.max_working ++;
|
});
|
|
if (limit_worker_max_reached)
|
continue;
|
|
hill_climbing_force_change (counter._.max_working, TRANSITION_STARVATION);
|
|
for (i = 0; i < 5; ++i) {
|
if (mono_runtime_is_shutting_down ())
|
break;
|
|
if (worker_try_unpark ()) {
|
mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] monitor thread, unparked",
|
GUINT_TO_POINTER (MONO_NATIVE_THREAD_ID_TO_UINT (mono_native_thread_id_get ())));
|
break;
|
}
|
|
if (worker_try_create ()) {
|
mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] monitor thread, created",
|
GUINT_TO_POINTER (MONO_NATIVE_THREAD_ID_TO_UINT (mono_native_thread_id_get ())));
|
break;
|
}
|
}
|
} while (monitor_should_keep_running ());
|
|
// printf ("monitor_thread: stop\n");
|
|
mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] monitor thread, finished",
|
GUINT_TO_POINTER (MONO_NATIVE_THREAD_ID_TO_UINT (mono_native_thread_id_get ())));
|
|
mono_refcount_dec (&worker);
|
return 0;
|
}
|
|
static void
|
monitor_ensure_running (void)
|
{
|
MonoError error;
|
for (;;) {
|
switch (worker.monitor_status) {
|
case MONITOR_STATUS_REQUESTED:
|
// printf ("monitor_thread: requested\n");
|
return;
|
case MONITOR_STATUS_WAITING_FOR_REQUEST:
|
// printf ("monitor_thread: waiting for request\n");
|
mono_atomic_cas_i32 (&worker.monitor_status, MONITOR_STATUS_REQUESTED, MONITOR_STATUS_WAITING_FOR_REQUEST);
|
break;
|
case MONITOR_STATUS_NOT_RUNNING:
|
// printf ("monitor_thread: not running\n");
|
if (mono_runtime_is_shutting_down ())
|
return;
|
if (mono_atomic_cas_i32 (&worker.monitor_status, MONITOR_STATUS_REQUESTED, MONITOR_STATUS_NOT_RUNNING) == MONITOR_STATUS_NOT_RUNNING) {
|
// printf ("monitor_thread: creating\n");
|
if (!mono_thread_create_internal (mono_get_root_domain (), monitor_thread, NULL, MONO_THREAD_CREATE_FLAGS_THREADPOOL | MONO_THREAD_CREATE_FLAGS_SMALL_STACK, &error)) {
|
// printf ("monitor_thread: creating failed\n");
|
worker.monitor_status = MONITOR_STATUS_NOT_RUNNING;
|
mono_error_cleanup (&error);
|
mono_refcount_dec (&worker);
|
}
|
return;
|
}
|
break;
|
default: g_assert_not_reached ();
|
}
|
}
|
}
|
|
static void
|
hill_climbing_change_thread_count (gint16 new_thread_count, ThreadPoolHeuristicStateTransition transition)
|
{
|
ThreadPoolHillClimbing *hc;
|
|
hc = &worker.heuristic_hill_climbing;
|
|
mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] hill climbing, change max number of threads %d",
|
GUINT_TO_POINTER (MONO_NATIVE_THREAD_ID_TO_UINT (mono_native_thread_id_get ())), new_thread_count);
|
|
hc->last_thread_count = new_thread_count;
|
hc->current_sample_interval = rand_next (&hc->random_interval_generator, hc->sample_interval_low, hc->sample_interval_high);
|
hc->elapsed_since_last_change = 0;
|
hc->completions_since_last_change = 0;
|
}
|
|
static void
|
hill_climbing_force_change (gint16 new_thread_count, ThreadPoolHeuristicStateTransition transition)
|
{
|
ThreadPoolHillClimbing *hc;
|
|
hc = &worker.heuristic_hill_climbing;
|
|
if (new_thread_count != hc->last_thread_count) {
|
hc->current_control_setting += new_thread_count - hc->last_thread_count;
|
hill_climbing_change_thread_count (new_thread_count, transition);
|
}
|
}
|
|
static double_complex
|
hill_climbing_get_wave_component (gdouble *samples, guint sample_count, gdouble period)
|
{
|
ThreadPoolHillClimbing *hc;
|
gdouble w, cosine, sine, coeff, q0, q1, q2;
|
guint i;
|
|
g_assert (sample_count >= period);
|
g_assert (period >= 2);
|
|
hc = &worker.heuristic_hill_climbing;
|
|
w = 2.0 * M_PI / period;
|
cosine = cos (w);
|
sine = sin (w);
|
coeff = 2.0 * cosine;
|
q0 = q1 = q2 = 0;
|
|
for (i = 0; i < sample_count; ++i) {
|
q0 = coeff * q1 - q2 + samples [(hc->total_samples - sample_count + i) % hc->samples_to_measure];
|
q2 = q1;
|
q1 = q0;
|
}
|
|
return mono_double_complex_scalar_div (mono_double_complex_make (q1 - q2 * cosine, (q2 * sine)), ((gdouble)sample_count));
|
}
|
|
static gint16
|
hill_climbing_update (gint16 current_thread_count, guint32 sample_duration, gint32 completions, gint64 *adjustment_interval)
|
{
|
ThreadPoolHillClimbing *hc;
|
ThreadPoolHeuristicStateTransition transition;
|
gdouble throughput;
|
gdouble throughput_error_estimate;
|
gdouble confidence;
|
gdouble move;
|
gdouble gain;
|
gint sample_index;
|
gint sample_count;
|
gint new_thread_wave_magnitude;
|
gint new_thread_count;
|
double_complex thread_wave_component;
|
double_complex throughput_wave_component;
|
double_complex ratio;
|
|
g_assert (adjustment_interval);
|
|
hc = &worker.heuristic_hill_climbing;
|
|
/* If someone changed the thread count without telling us, update our records accordingly. */
|
if (current_thread_count != hc->last_thread_count)
|
hill_climbing_force_change (current_thread_count, TRANSITION_INITIALIZING);
|
|
/* Update the cumulative stats for this thread count */
|
hc->elapsed_since_last_change += sample_duration;
|
hc->completions_since_last_change += completions;
|
|
/* Add in any data we've already collected about this sample */
|
sample_duration += hc->accumulated_sample_duration;
|
completions += hc->accumulated_completion_count;
|
|
/* We need to make sure we're collecting reasonably accurate data. Since we're just counting the end
|
* of each work item, we are goinng to be missing some data about what really happened during the
|
* sample interval. The count produced by each thread includes an initial work item that may have
|
* started well before the start of the interval, and each thread may have been running some new
|
* work item for some time before the end of the interval, which did not yet get counted. So
|
* our count is going to be off by +/- threadCount workitems.
|
*
|
* The exception is that the thread that reported to us last time definitely wasn't running any work
|
* at that time, and the thread that's reporting now definitely isn't running a work item now. So
|
* we really only need to consider threadCount-1 threads.
|
*
|
* Thus the percent error in our count is +/- (threadCount-1)/numCompletions.
|
*
|
* We cannot rely on the frequency-domain analysis we'll be doing later to filter out this error, because
|
* of the way it accumulates over time. If this sample is off by, say, 33% in the negative direction,
|
* then the next one likely will be too. The one after that will include the sum of the completions
|
* we missed in the previous samples, and so will be 33% positive. So every three samples we'll have
|
* two "low" samples and one "high" sample. This will appear as periodic variation right in the frequency
|
* range we're targeting, which will not be filtered by the frequency-domain translation. */
|
if (hc->total_samples > 0 && ((current_thread_count - 1.0) / completions) >= hc->max_sample_error) {
|
/* Not accurate enough yet. Let's accumulate the data so
|
* far, and tell the ThreadPoolWorker to collect a little more. */
|
hc->accumulated_sample_duration = sample_duration;
|
hc->accumulated_completion_count = completions;
|
*adjustment_interval = 10;
|
return current_thread_count;
|
}
|
|
/* We've got enouugh data for our sample; reset our accumulators for next time. */
|
hc->accumulated_sample_duration = 0;
|
hc->accumulated_completion_count = 0;
|
|
/* Add the current thread count and throughput sample to our history. */
|
throughput = ((gdouble) completions) / sample_duration;
|
|
sample_index = hc->total_samples % hc->samples_to_measure;
|
hc->samples [sample_index] = throughput;
|
hc->thread_counts [sample_index] = current_thread_count;
|
hc->total_samples ++;
|
|
/* Set up defaults for our metrics. */
|
thread_wave_component = mono_double_complex_make(0, 0);
|
throughput_wave_component = mono_double_complex_make(0, 0);
|
throughput_error_estimate = 0;
|
ratio = mono_double_complex_make(0, 0);
|
confidence = 0;
|
|
transition = TRANSITION_WARMUP;
|
|
/* How many samples will we use? It must be at least the three wave periods we're looking for, and it must also
|
* be a whole multiple of the primary wave's period; otherwise the frequency we're looking for will fall between
|
* two frequency bands in the Fourier analysis, and we won't be able to measure it accurately. */
|
sample_count = ((gint) MIN (hc->total_samples - 1, hc->samples_to_measure) / hc->wave_period) * hc->wave_period;
|
|
if (sample_count > hc->wave_period) {
|
guint i;
|
gdouble average_throughput;
|
gdouble average_thread_count;
|
gdouble sample_sum = 0;
|
gdouble thread_sum = 0;
|
|
/* Average the throughput and thread count samples, so we can scale the wave magnitudes later. */
|
for (i = 0; i < sample_count; ++i) {
|
guint j = (hc->total_samples - sample_count + i) % hc->samples_to_measure;
|
sample_sum += hc->samples [j];
|
thread_sum += hc->thread_counts [j];
|
}
|
|
average_throughput = sample_sum / sample_count;
|
average_thread_count = thread_sum / sample_count;
|
|
if (average_throughput > 0 && average_thread_count > 0) {
|
gdouble noise_for_confidence, adjacent_period_1, adjacent_period_2;
|
|
/* Calculate the periods of the adjacent frequency bands we'll be using to
|
* measure noise levels. We want the two adjacent Fourier frequency bands. */
|
adjacent_period_1 = sample_count / (((gdouble) sample_count) / ((gdouble) hc->wave_period) + 1);
|
adjacent_period_2 = sample_count / (((gdouble) sample_count) / ((gdouble) hc->wave_period) - 1);
|
|
/* Get the the three different frequency components of the throughput (scaled by average
|
* throughput). Our "error" estimate (the amount of noise that might be present in the
|
* frequency band we're really interested in) is the average of the adjacent bands. */
|
throughput_wave_component = mono_double_complex_scalar_div (hill_climbing_get_wave_component (hc->samples, sample_count, hc->wave_period), average_throughput);
|
throughput_error_estimate = cabs (mono_double_complex_scalar_div (hill_climbing_get_wave_component (hc->samples, sample_count, adjacent_period_1), average_throughput));
|
|
if (adjacent_period_2 <= sample_count) {
|
throughput_error_estimate = MAX (throughput_error_estimate, cabs (mono_double_complex_scalar_div (hill_climbing_get_wave_component (
|
hc->samples, sample_count, adjacent_period_2), average_throughput)));
|
}
|
|
/* Do the same for the thread counts, so we have something to compare to. We don't
|
* measure thread count noise, because there is none; these are exact measurements. */
|
thread_wave_component = mono_double_complex_scalar_div (hill_climbing_get_wave_component (hc->thread_counts, sample_count, hc->wave_period), average_thread_count);
|
|
/* Update our moving average of the throughput noise. We'll use this
|
* later as feedback to determine the new size of the thread wave. */
|
if (hc->average_throughput_noise == 0) {
|
hc->average_throughput_noise = throughput_error_estimate;
|
} else {
|
hc->average_throughput_noise = (hc->throughput_error_smoothing_factor * throughput_error_estimate)
|
+ ((1.0 + hc->throughput_error_smoothing_factor) * hc->average_throughput_noise);
|
}
|
|
if (cabs (thread_wave_component) > 0) {
|
/* Adjust the throughput wave so it's centered around the target wave,
|
* and then calculate the adjusted throughput/thread ratio. */
|
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);
|
transition = TRANSITION_CLIMBING_MOVE;
|
} else {
|
ratio = mono_double_complex_make (0, 0);
|
transition = TRANSITION_STABILIZING;
|
}
|
|
noise_for_confidence = MAX (hc->average_throughput_noise, throughput_error_estimate);
|
if (noise_for_confidence > 0) {
|
confidence = cabs (thread_wave_component) / noise_for_confidence / hc->target_signal_to_noise_ratio;
|
} else {
|
/* there is no noise! */
|
confidence = 1.0;
|
}
|
}
|
}
|
|
/* We use just the real part of the complex ratio we just calculated. If the throughput signal
|
* is exactly in phase with the thread signal, this will be the same as taking the magnitude of
|
* the complex move and moving that far up. If they're 180 degrees out of phase, we'll move
|
* backward (because this indicates that our changes are having the opposite of the intended effect).
|
* If they're 90 degrees out of phase, we won't move at all, because we can't tell wether we're
|
* having a negative or positive effect on throughput. */
|
move = creal (ratio);
|
move = CLAMP (move, -1.0, 1.0);
|
|
/* Apply our confidence multiplier. */
|
move *= CLAMP (confidence, -1.0, 1.0);
|
|
/* Now apply non-linear gain, such that values around zero are attenuated, while higher values
|
* are enhanced. This allows us to move quickly if we're far away from the target, but more slowly
|
* if we're getting close, giving us rapid ramp-up without wild oscillations around the target. */
|
gain = hc->max_change_per_second * sample_duration;
|
move = pow (fabs (move), hc->gain_exponent) * (move >= 0.0 ? 1 : -1) * gain;
|
move = MIN (move, hc->max_change_per_sample);
|
|
/* If the result was positive, and CPU is > 95%, refuse the move. */
|
if (move > 0.0 && worker.cpu_usage > CPU_USAGE_HIGH)
|
move = 0.0;
|
|
/* Apply the move to our control setting. */
|
hc->current_control_setting += move;
|
|
/* Calculate the new thread wave magnitude, which is based on the moving average we've been keeping of the
|
* throughput error. This average starts at zero, so we'll start with a nice safe little wave at first. */
|
new_thread_wave_magnitude = (gint)(0.5 + (hc->current_control_setting * hc->average_throughput_noise
|
* hc->target_signal_to_noise_ratio * hc->thread_magnitude_multiplier * 2.0));
|
new_thread_wave_magnitude = CLAMP (new_thread_wave_magnitude, 1, hc->max_thread_wave_magnitude);
|
|
/* Make sure our control setting is within the ThreadPoolWorker's limits. */
|
hc->current_control_setting = CLAMP (hc->current_control_setting, worker.limit_worker_min, worker.limit_worker_max - new_thread_wave_magnitude);
|
|
/* Calculate the new thread count (control setting + square wave). */
|
new_thread_count = (gint)(hc->current_control_setting + new_thread_wave_magnitude * ((hc->total_samples / (hc->wave_period / 2)) % 2));
|
|
/* Make sure the new thread count doesn't exceed the ThreadPoolWorker's limits. */
|
new_thread_count = CLAMP (new_thread_count, worker.limit_worker_min, worker.limit_worker_max);
|
|
if (new_thread_count != current_thread_count)
|
hill_climbing_change_thread_count (new_thread_count, transition);
|
|
if (creal (ratio) < 0.0 && new_thread_count == worker.limit_worker_min)
|
*adjustment_interval = (gint)(0.5 + hc->current_sample_interval * (10.0 * MAX (-1.0 * creal (ratio), 1.0)));
|
else
|
*adjustment_interval = hc->current_sample_interval;
|
|
return new_thread_count;
|
}
|
|
static gboolean
|
heuristic_should_adjust (void)
|
{
|
if (worker.heuristic_last_dequeue > worker.heuristic_last_adjustment + worker.heuristic_adjustment_interval) {
|
ThreadPoolWorkerCounter counter;
|
counter = COUNTER_READ ();
|
if (counter._.working <= counter._.max_working)
|
return TRUE;
|
}
|
|
return FALSE;
|
}
|
|
static void
|
heuristic_adjust (void)
|
{
|
if (mono_coop_mutex_trylock (&worker.heuristic_lock) == 0) {
|
gint32 completions = mono_atomic_xchg_i32 (&worker.heuristic_completions, 0);
|
gint64 sample_end = mono_msec_ticks ();
|
gint64 sample_duration = sample_end - worker.heuristic_sample_start;
|
|
if (sample_duration >= worker.heuristic_adjustment_interval / 2) {
|
ThreadPoolWorkerCounter counter;
|
gint16 new_thread_count;
|
|
counter = COUNTER_READ ();
|
new_thread_count = hill_climbing_update (counter._.max_working, sample_duration, completions, &worker.heuristic_adjustment_interval);
|
|
COUNTER_ATOMIC (counter, {
|
counter._.max_working = new_thread_count;
|
});
|
|
if (new_thread_count > counter._.max_working)
|
worker_request ();
|
|
worker.heuristic_sample_start = sample_end;
|
worker.heuristic_last_adjustment = mono_msec_ticks ();
|
}
|
|
mono_coop_mutex_unlock (&worker.heuristic_lock);
|
}
|
}
|
|
static void
|
heuristic_notify_work_completed (void)
|
{
|
mono_atomic_inc_i32 (&worker.heuristic_completions);
|
worker.heuristic_last_dequeue = mono_msec_ticks ();
|
|
if (heuristic_should_adjust ())
|
heuristic_adjust ();
|
}
|
|
gboolean
|
mono_threadpool_worker_notify_completed (void)
|
{
|
ThreadPoolWorkerCounter counter;
|
|
heuristic_notify_work_completed ();
|
|
counter = COUNTER_READ ();
|
return counter._.working <= counter._.max_working;
|
}
|
|
gint32
|
mono_threadpool_worker_get_min (void)
|
{
|
gint32 ret;
|
|
if (!mono_refcount_tryinc (&worker))
|
return 0;
|
|
ret = worker.limit_worker_min;
|
|
mono_refcount_dec (&worker);
|
return ret;
|
}
|
|
gboolean
|
mono_threadpool_worker_set_min (gint32 value)
|
{
|
if (value <= 0 || value > worker.limit_worker_max)
|
return FALSE;
|
|
if (!mono_refcount_tryinc (&worker))
|
return FALSE;
|
|
worker.limit_worker_min = value;
|
|
mono_refcount_dec (&worker);
|
return TRUE;
|
}
|
|
gint32
|
mono_threadpool_worker_get_max (void)
|
{
|
gint32 ret;
|
|
if (!mono_refcount_tryinc (&worker))
|
return 0;
|
|
ret = worker.limit_worker_max;
|
|
mono_refcount_dec (&worker);
|
return ret;
|
}
|
|
gboolean
|
mono_threadpool_worker_set_max (gint32 value)
|
{
|
gint32 cpu_count;
|
|
cpu_count = mono_cpu_count ();
|
if (value < worker.limit_worker_min || value < cpu_count)
|
return FALSE;
|
|
if (!mono_refcount_tryinc (&worker))
|
return FALSE;
|
|
worker.limit_worker_max = value;
|
|
mono_refcount_dec (&worker);
|
return TRUE;
|
}
|
|
void
|
mono_threadpool_worker_set_suspended (gboolean suspended)
|
{
|
if (!mono_refcount_tryinc (&worker))
|
return;
|
|
worker.suspended = suspended;
|
if (!suspended)
|
worker_request ();
|
|
mono_refcount_dec (&worker);
|
}
|
