private static void WorkerThreadStart()
{
Thread.CurrentThread.SetThreadPoolWorkerThreadName();
PortableThreadPool threadPoolInstance = ThreadPoolInstance;
if (PortableThreadPoolEventSource.Log.IsEnabled())
{
PortableThreadPoolEventSource.Log.ThreadPoolWorkerThreadStart(
(uint)threadPoolInstance._separated.counts.VolatileRead().NumExistingThreads);
}
LowLevelLock hillClimbingThreadAdjustmentLock = threadPoolInstance._hillClimbingThreadAdjustmentLock;
LowLevelLifoSemaphore semaphore = s_semaphore;
while (true)
{
bool spinWait = true;
while (semaphore.Wait(ThreadPoolThreadTimeoutMs, spinWait))
{
bool alreadyRemovedWorkingWorker = false;
while (TakeActiveRequest(threadPoolInstance))
{
Volatile.Write(ref threadPoolInstance._separated.lastDequeueTime, Environment.TickCount);
if (!ThreadPoolWorkQueue.Dispatch())
{
// ShouldStopProcessingWorkNow() caused the thread to stop processing work, and it would have
// already removed this working worker in the counts. This typically happens when hill climbing
// decreases the worker thread count goal.
alreadyRemovedWorkingWorker = true;
break;
}
}
// Don't spin-wait on the semaphore next time if the thread was actively stopped from processing work,
// as it's unlikely that the worker thread count goal would be increased again so soon afterwards that
// the semaphore would be released within the spin-wait window
spinWait = !alreadyRemovedWorkingWorker;
if (!alreadyRemovedWorkingWorker)
{
// If we woke up but couldn't find a request, or ran out of work items to process, we need to update
// the number of working workers to reflect that we are done working for now
RemoveWorkingWorker(threadPoolInstance);
}
}
hillClimbingThreadAdjustmentLock.Acquire();
try
{
// At this point, the thread's wait timed out. We are shutting down this thread.
// We are going to decrement the number of exisiting threads to no longer include this one
// and then change the max number of threads in the thread pool to reflect that we don't need as many
// as we had. Finally, we are going to tell hill climbing that we changed the max number of threads.
ThreadCounts counts = threadPoolInstance._separated.counts.VolatileRead();
while (true)
{
// Since this thread is currently registered as an existing thread, if more work comes in meanwhile,
// this thread would be expected to satisfy the new work. Ensure that NumExistingThreads is not
// decreased below NumProcessingWork, as that would be indicative of such a case.
short numExistingThreads = counts.NumExistingThreads;
if (numExistingThreads <= counts.NumProcessingWork)
{
// In this case, enough work came in that this thread should not time out and should go back to work.
break;
}
ThreadCounts newCounts = counts;
newCounts.SubtractNumExistingThreads(1);
short newNumExistingThreads = (short)(numExistingThreads - 1);
short newNumThreadsGoal = Math.Max(threadPoolInstance._minThreads, Math.Min(newNumExistingThreads, newCounts.NumThreadsGoal));
newCounts.NumThreadsGoal = newNumThreadsGoal;
ThreadCounts oldCounts = threadPoolInstance._separated.counts.InterlockedCompareExchange(newCounts, counts);
if (oldCounts == counts)
{
HillClimbing.ThreadPoolHillClimber.ForceChange(newNumThreadsGoal, HillClimbing.StateOrTransition.ThreadTimedOut);
if (PortableThreadPoolEventSource.Log.IsEnabled())
{
PortableThreadPoolEventSource.Log.ThreadPoolWorkerThreadStop((uint)newNumExistingThreads);
}
return;
}
counts = oldCounts;
}
}
finally
{
hillClimbingThreadAdjustmentLock.Release();
}
}
}
