2 * sgen-thread-pool.c: Threadpool for all concurrent GC work.
4 * Copyright (C) 2015 Xamarin Inc
6 * Licensed under the MIT license. See LICENSE file in the project root for full license information.
12 #include "mono/sgen/sgen-gc.h"
13 #include "mono/sgen/sgen-thread-pool.h"
14 #include "mono/sgen/sgen-pointer-queue.h"
15 #include "mono/utils/mono-os-mutex.h"
16 #ifndef SGEN_WITHOUT_MONO
17 #include "mono/utils/mono-threads.h"
20 #define MAX_NUM_THREADS 8
22 static mono_mutex_t lock;
23 static mono_cond_t work_cond;
24 static mono_cond_t done_cond;
26 static int threads_num = 0;
27 static MonoNativeThreadId threads [MAX_NUM_THREADS];
29 /* Only accessed with the lock held. */
30 static SgenPointerQueue job_queue;
32 static SgenThreadPoolThreadInitFunc thread_init_func;
33 static SgenThreadPoolIdleJobFunc idle_job_func;
34 static SgenThreadPoolContinueIdleJobFunc continue_idle_job_func;
35 static SgenThreadPoolShouldWorkFunc should_work_func;
37 static volatile gboolean threadpool_shutdown;
38 static volatile int threads_finished = 0;
46 /* Assumes that the lock is held. */
47 static SgenThreadPoolJob*
48 get_job_and_set_in_progress (void)
50 for (size_t i = 0; i < job_queue.next_slot; ++i) {
51 SgenThreadPoolJob *job = (SgenThreadPoolJob *)job_queue.data [i];
52 if (job->state == STATE_WAITING) {
53 job->state = STATE_IN_PROGRESS;
60 /* Assumes that the lock is held. */
62 find_job_in_queue (SgenThreadPoolJob *job)
64 for (ssize_t i = 0; i < job_queue.next_slot; ++i) {
65 if (job_queue.data [i] == job)
71 /* Assumes that the lock is held. */
73 remove_job (SgenThreadPoolJob *job)
76 SGEN_ASSERT (0, job->state == STATE_DONE, "Why are we removing a job that's not done?");
77 index = find_job_in_queue (job);
78 SGEN_ASSERT (0, index >= 0, "Why is the job we're trying to remove not in the queue?");
79 job_queue.data [index] = NULL;
80 sgen_pointer_queue_remove_nulls (&job_queue);
81 sgen_thread_pool_job_free (job);
85 continue_idle_job (void *thread_data)
87 if (!continue_idle_job_func)
89 return continue_idle_job_func (thread_data);
93 should_work (void *thread_data)
95 if (!should_work_func)
97 return should_work_func (thread_data);
100 static mono_native_thread_return_t
101 thread_func (void *thread_data)
103 thread_init_func (thread_data);
105 mono_os_mutex_lock (&lock);
108 SgenThreadPoolJob *job;
110 if (!should_work (thread_data)) {
111 mono_os_cond_wait (&work_cond, &lock);
115 * It's important that we check the continue idle flag with the lock held.
116 * Suppose we didn't check with the lock held, and the result is FALSE. The
117 * main thread might then set continue idle and signal us before we can take
118 * the lock, and we'd lose the signal.
120 do_idle = continue_idle_job (thread_data);
121 job = get_job_and_set_in_progress ();
123 if (!job && !do_idle && !threadpool_shutdown) {
125 * pthread_cond_wait() can return successfully despite the condition
126 * not being signalled, so we have to run this in a loop until we
127 * really have work to do.
129 mono_os_cond_wait (&work_cond, &lock);
133 mono_os_mutex_unlock (&lock);
136 job->func (thread_data, job);
138 mono_os_mutex_lock (&lock);
140 SGEN_ASSERT (0, job->state == STATE_IN_PROGRESS, "The job should still be in progress.");
141 job->state = STATE_DONE;
144 * Only the main GC thread will ever wait on the done condition, so we don't
147 mono_os_cond_signal (&done_cond);
148 } else if (do_idle) {
149 SGEN_ASSERT (0, idle_job_func, "Why do we have idle work when there's no idle job function?");
151 idle_job_func (thread_data);
152 do_idle = continue_idle_job (thread_data);
153 } while (do_idle && !job_queue.next_slot);
155 mono_os_mutex_lock (&lock);
158 mono_os_cond_signal (&done_cond);
160 SGEN_ASSERT (0, threadpool_shutdown, "Why did we unlock if no jobs and not shutting down?");
161 mono_os_mutex_lock (&lock);
163 mono_os_cond_signal (&done_cond);
164 mono_os_mutex_unlock (&lock);
169 return (mono_native_thread_return_t)0;
173 sgen_thread_pool_init (int num_threads, SgenThreadPoolThreadInitFunc init_func, SgenThreadPoolIdleJobFunc idle_func, SgenThreadPoolContinueIdleJobFunc continue_idle_func, SgenThreadPoolShouldWorkFunc should_work_func_p, void **thread_datas)
177 threads_num = (num_threads < MAX_NUM_THREADS) ? num_threads : MAX_NUM_THREADS;
179 mono_os_mutex_init (&lock);
180 mono_os_cond_init (&work_cond);
181 mono_os_cond_init (&done_cond);
183 thread_init_func = init_func;
184 idle_job_func = idle_func;
185 continue_idle_job_func = continue_idle_func;
186 should_work_func = should_work_func_p;
188 for (i = 0; i < threads_num; i++)
189 mono_native_thread_create (&threads [i], thread_func, thread_datas ? thread_datas [i] : NULL);
193 sgen_thread_pool_shutdown (void)
198 mono_os_mutex_lock (&lock);
199 threadpool_shutdown = TRUE;
200 mono_os_cond_broadcast (&work_cond);
201 while (threads_finished < threads_num)
202 mono_os_cond_wait (&done_cond, &lock);
203 mono_os_mutex_unlock (&lock);
205 mono_os_mutex_destroy (&lock);
206 mono_os_cond_destroy (&work_cond);
207 mono_os_cond_destroy (&done_cond);
211 sgen_thread_pool_job_alloc (const char *name, SgenThreadPoolJobFunc func, size_t size)
213 SgenThreadPoolJob *job = (SgenThreadPoolJob *)sgen_alloc_internal_dynamic (size, INTERNAL_MEM_THREAD_POOL_JOB, TRUE);
216 job->state = STATE_WAITING;
222 sgen_thread_pool_job_free (SgenThreadPoolJob *job)
224 sgen_free_internal_dynamic (job, job->size, INTERNAL_MEM_THREAD_POOL_JOB);
228 sgen_thread_pool_job_enqueue (SgenThreadPoolJob *job)
230 mono_os_mutex_lock (&lock);
232 sgen_pointer_queue_add (&job_queue, job);
233 mono_os_cond_signal (&work_cond);
235 mono_os_mutex_unlock (&lock);
239 sgen_thread_pool_job_wait (SgenThreadPoolJob *job)
241 SGEN_ASSERT (0, job, "Where's the job?");
243 mono_os_mutex_lock (&lock);
245 while (find_job_in_queue (job) >= 0)
246 mono_os_cond_wait (&done_cond, &lock);
248 mono_os_mutex_unlock (&lock);
252 sgen_thread_pool_idle_signal (void)
254 SGEN_ASSERT (0, idle_job_func, "Why are we signaling idle without an idle function?");
256 mono_os_mutex_lock (&lock);
258 if (continue_idle_job_func (NULL))
259 mono_os_cond_broadcast (&work_cond);
261 mono_os_mutex_unlock (&lock);
265 sgen_thread_pool_idle_wait (void)
267 SGEN_ASSERT (0, idle_job_func, "Why are we waiting for idle without an idle function?");
269 mono_os_mutex_lock (&lock);
271 while (continue_idle_job_func (NULL))
272 mono_os_cond_wait (&done_cond, &lock);
274 mono_os_mutex_unlock (&lock);
278 sgen_thread_pool_wait_for_all_jobs (void)
280 mono_os_mutex_lock (&lock);
282 while (!sgen_pointer_queue_is_empty (&job_queue))
283 mono_os_cond_wait (&done_cond, &lock);
285 mono_os_mutex_unlock (&lock);
288 /* Return 0 if is not a thread pool thread or the thread number otherwise */
290 sgen_thread_pool_is_thread_pool_thread (MonoNativeThreadId some_thread)
294 for (i = 0; i < threads_num; i++) {
295 if (some_thread == threads [i])