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DispatchPool works again, but performance is poor in some cases
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r21:6a56df4ec59e promises
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@@ -151,7 +151,7 namespace Implab.Test {
151 var pool = new WorkerPool(5, 20);
151 var pool = new WorkerPool(5, 20);
152 Assert.AreEqual(5, pool.PoolSize);
152 Assert.AreEqual(5, pool.PoolSize);
153 pool.Dispose();
153 pool.Dispose();
154 Thread.Sleep(200);
154 Thread.Sleep(500);
155 Assert.AreEqual(0, pool.PoolSize);
155 Assert.AreEqual(0, pool.PoolSize);
156 pool.Dispose();
156 pool.Dispose();
157 }
157 }
@@ -244,7 +244,7 namespace Implab.Test {
244 [TestMethod]
244 [TestMethod]
245 public void ChainedMapTest() {
245 public void ChainedMapTest() {
246
246
247 using (var pool = new WorkerPool(0,100,0)) {
247 using (var pool = new WorkerPool(0,100,1)) {
248 int count = 10000;
248 int count = 10000;
249
249
250 double[] args = new double[count];
250 double[] args = new double[count];
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@@ -9,12 +9,15 namespace Implab.Parallels {
9 public abstract class DispatchPool<TUnit> : IDisposable {
9 public abstract class DispatchPool<TUnit> : IDisposable {
10 readonly int m_minThreads;
10 readonly int m_minThreads;
11 readonly int m_maxThreads;
11 readonly int m_maxThreads;
12 int m_createdThreads = 0;
12
13 int m_activeThreads = 0;
13 int m_createdThreads = 0; // the current size of the pool
14 int m_sleepingThreads = 0;
14 int m_activeThreads = 0; // the count of threads which are active
15 int m_maxRunningThreads = 0;
15 int m_sleepingThreads = 0; // the count of currently inactive threads
16 int m_exitRequired = 0;
16 int m_maxRunningThreads = 0; // the meximum reached size of the pool
17 int m_releaseTimeout = 100; // timeout while the working thread will wait for the new tasks before exit
17 int m_exitRequired = 0; // the pool is going to shutdown, all unused workers are released
18 int m_releaseTimeout = 100; // the timeout while the working thread will wait for the new tasks before exit
19 int m_wakeEvents = 0; // the count of wake events
20
18 AutoResetEvent m_hasTasks = new AutoResetEvent(false);
21 AutoResetEvent m_hasTasks = new AutoResetEvent(false);
19
22
20 protected DispatchPool(int min, int max) {
23 protected DispatchPool(int min, int max) {
@@ -72,26 +75,43 namespace Implab.Parallels {
72
75
73 protected abstract bool TryDequeue(out TUnit unit);
76 protected abstract bool TryDequeue(out TUnit unit);
74
77
75 protected virtual bool ExtendPool() {
78 #region thread execution traits
76 if (m_sleepingThreads == 0)
79 int SignalThread() {
77 // no sleeping workers are available
80 var signals = Interlocked.Increment(ref m_wakeEvents);
78 // try create one
81 if(signals == 1)
79 return StartWorker();
82 m_hasTasks.Set();
80 else {
83 return signals;
81 // we can get here a race condition when several threads asks to extend pool
82 // and some sleaping threads are exited due timeout but they are still counted as sleeping
83 // in that case all of this threads could exit except one
84 WakePool();
85 return true;
86 }
84 }
87
85
86 bool Sleep(int timeout) {
87 Interlocked.Increment(ref m_sleepingThreads);
88 if (m_hasTasks.WaitOne(timeout)) {
89 // this is autoreset event, only one thread can run this block simultaneously
90 var sleeping = Interlocked.Decrement(ref m_sleepingThreads);
91 if (Interlocked.Decrement(ref m_wakeEvents) > 0)
92 m_hasTasks.Set(); // wake next worker
93
94 return true;
95 } else {
96 Interlocked.Decrement(ref m_sleepingThreads);
97 return false;
88 }
98 }
99 }
100 #endregion
89
101
90 /// <summary>
102 /// <summary>
91 /// Запускает либо новый поток, если раньше не было ни одного потока, либо устанавливает событие пробуждение одного спящего потока
103 /// Запускает либо новый поток, если раньше не было ни одного потока, либо устанавливает событие пробуждение одного спящего потока
92 /// </summary>
104 /// </summary>
93 protected void WakePool() {
105 protected void GrowPool() {
94 m_hasTasks.Set(); // wake sleeping thread;
106 if (m_exitRequired != 0)
107 return;
108 if (m_sleepingThreads > m_wakeEvents) {
109 // all sleeping threads may gone
110 SignalThread(); // wake a sleeping thread;
111
112 // we can't check whether signal has been processed
113 // anyway it may take some time for the thread to start
114 // we will ensure that at least one thread is running
95
115
96 if (AllocateThreadSlot(1)) {
116 if (AllocateThreadSlot(1)) {
97 // if there were no threads in the pool
117 // if there were no threads in the pool
@@ -99,42 +119,45 namespace Implab.Parallels {
99 worker.IsBackground = true;
119 worker.IsBackground = true;
100 worker.Start();
120 worker.Start();
101 }
121 }
122 } else {
123 // if there is no sleeping threads in the pool
124 StartWorker();
125 }
102 }
126 }
103
127
104 bool Sleep(int timeout) {
128 private bool Suspend() {
105 Interlocked.Increment(ref m_sleepingThreads);
106 var result = m_hasTasks.WaitOne(timeout);
107 Interlocked.Decrement(ref m_sleepingThreads);
108 return result;
109 }
110
111 protected virtual bool Suspend() {
112 //no tasks left, exit if the thread is no longer needed
129 //no tasks left, exit if the thread is no longer needed
113 bool last;
130 bool last;
114 bool requestExit;
131 bool requestExit;
115
132
133
134
135 // if threads have a timeout before releasing
116 if (m_releaseTimeout > 0)
136 if (m_releaseTimeout > 0)
117 requestExit = !Sleep(m_releaseTimeout);
137 requestExit = !Sleep(m_releaseTimeout);
118 else
138 else
119 requestExit = true;
139 requestExit = true;
120
140
141 if (!requestExit)
142 return true;
121
143
144 // release unsused thread
122 if (requestExit && ReleaseThreadSlot(out last)) {
145 if (requestExit && ReleaseThreadSlot(out last)) {
123 // in case at the moment the last thread was being released
146 // in case at the moment the last thread was being released
124 // a new task was added to the queue, we need to try
147 // a new task was added to the queue, we need to try
125 // to revoke the thread to avoid the situation when the task is left unprocessed
148 // to revoke the thread to avoid the situation when the task is left unprocessed
126 if (last && m_hasTasks.WaitOne(0)) {
149 if (last && Sleep(0)) { // Sleep(0) will fetch pending task or will return false
127 if (AllocateThreadSlot(1))
150 if (AllocateThreadSlot(1))
128 return true; // spin again...
151 return true; // spin again...
129 else
152 else
130 // we failed to reallocate the first slot for this thread
153 SignalThread(); // since Sleep(0) has fetched the signal we neet to reschedule it
131 // therefore we need to release the event
154
132 m_hasTasks.Set();
133 }
155 }
134
156
135 return false;
157 return false;
136 }
158 }
137
159
160 // wait till infinity
138 Sleep(-1);
161 Sleep(-1);
139
162
140 return true;
163 return true;
@@ -215,7 +238,12 namespace Implab.Parallels {
215 }
238 }
216 }
239 }
217
240
218 bool FetchTask(out TUnit unit) {
241 protected abstract void InvokeUnit(TUnit unit);
242
243 void Worker() {
244 TUnit unit;
245 Interlocked.Increment(ref m_activeThreads);
246 Sleep(0); // remove wake request if the new thread is started
219 do {
247 do {
220 // exit if requested
248 // exit if requested
221 if (m_exitRequired != 0) {
249 if (m_exitRequired != 0) {
@@ -224,15 +252,15 namespace Implab.Parallels {
224 if (ReleaseThreadSlotAnyway()) // it was the last worker
252 if (ReleaseThreadSlotAnyway()) // it was the last worker
225 m_hasTasks.Dispose();
253 m_hasTasks.Dispose();
226 else
254 else
227 m_hasTasks.Set(); // wake next worker
255 SignalThread(); // wake next worker
228 unit = default(TUnit);
256 unit = default(TUnit);
229 return false;
257 break;
230 }
258 }
231
259
232 // fetch task
260 // fetch task
233 if (TryDequeue(out unit)) {
261 if (TryDequeue(out unit)) {
234 ExtendPool();
262 InvokeUnit(unit);
235 return true;
263 continue;
236 }
264 }
237
265
238 Interlocked.Decrement(ref m_activeThreads);
266 Interlocked.Decrement(ref m_activeThreads);
@@ -240,19 +268,11 namespace Implab.Parallels {
240 // entering suspend state
268 // entering suspend state
241 // keep this thread and wait
269 // keep this thread and wait
242 if (!Suspend())
270 if (!Suspend())
243 return false;
271 break;
244
272
245 Interlocked.Increment(ref m_activeThreads);
273 Interlocked.Increment(ref m_activeThreads);
246 } while (true);
274 } while (true);
247 }
248
275
249 protected abstract void InvokeUnit(TUnit unit);
250
251 void Worker() {
252 TUnit unit;
253 Interlocked.Increment(ref m_activeThreads);
254 while (FetchTask(out unit))
255 InvokeUnit(unit);
256 }
276 }
257
277
258 protected virtual void Dispose(bool disposing) {
278 protected virtual void Dispose(bool disposing) {
@@ -262,7 +282,10 namespace Implab.Parallels {
262 return;
282 return;
263
283
264 // wake sleeping threads
284 // wake sleeping threads
265 m_hasTasks.Set();
285 if (m_createdThreads > 0)
286 SignalThread();
287 else
288 m_hasTasks.Dispose();
266 GC.SuppressFinalize(this);
289 GC.SuppressFinalize(this);
267 }
290 }
268 }
291 }
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@@ -57,15 +57,8 namespace Implab.Parallels {
57 var len = Interlocked.Increment(ref m_queueLength);
57 var len = Interlocked.Increment(ref m_queueLength);
58 m_queue.Enqueue(unit);
58 m_queue.Enqueue(unit);
59
59
60 ExtendPool();
60 if (len > m_threshold*ActiveThreads)
61 }
61 GrowPool();
62
63 protected override bool ExtendPool() {
64 if (m_queueLength <= m_threshold*ActiveThreads)
65 // in this case we are in active thread and it request for additional workers
66 // satisfy it only when queue is longer than threshold
67 return false;
68 return base.ExtendPool();
69 }
62 }
70
63
71 protected override bool TryDequeue(out Action unit) {
64 protected override bool TryDequeue(out Action unit) {
@@ -80,11 +73,5 namespace Implab.Parallels {
80 unit();
73 unit();
81 }
74 }
82
75
83 protected override bool Suspend() {
84 if (m_queueLength == 0)
85 return base.Suspend();
86 else
87 return true; // spin again without locks...
88 }
76 }
89 }
77 }
90 }
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