private static void GateThreadStart()
{
bool disableStarvationDetection =
AppContextConfigHelper.GetBooleanConfig("System.Threading.ThreadPool.DisableStarvationDetection", false);
bool debuggerBreakOnWorkStarvation =
AppContextConfigHelper.GetBooleanConfig("System.Threading.ThreadPool.DebugBreakOnWorkerStarvation", false);
// The first reading is over a time range other than what we are focusing on, so we do not use the read other
// than to send it to any runtime-specific implementation that may also use the CPU utilization.
CpuUtilizationReader cpuUtilizationReader = default;
_ = cpuUtilizationReader.CurrentUtilization;
PortableThreadPool threadPoolInstance = ThreadPoolInstance;
LowLevelLock threadAdjustmentLock = threadPoolInstance._threadAdjustmentLock;
DelayHelper delayHelper = default;
if (BlockingConfig.IsCooperativeBlockingEnabled)
{
// Initialize memory usage and limits, and register to update them on gen 2 GCs
threadPoolInstance.OnGen2GCCallback();
Gen2GcCallback.Register(threadPoolInstance.OnGen2GCCallback);
}
while (true)
{
RunGateThreadEvent.WaitOne();
int currentTimeMs = Environment.TickCount;
delayHelper.SetGateActivitiesTime(currentTimeMs);
while (true)
{
bool wasSignaledToWake = DelayEvent.WaitOne((int)delayHelper.GetNextDelay(currentTimeMs));
currentTimeMs = Environment.TickCount;
// Thread count adjustment for cooperative blocking
do
{
PendingBlockingAdjustment pendingBlockingAdjustment = threadPoolInstance._pendingBlockingAdjustment;
if (pendingBlockingAdjustment == PendingBlockingAdjustment.None)
{
delayHelper.ClearBlockingAdjustmentDelay();
break;
}
bool previousDelayElapsed = false;
if (delayHelper.HasBlockingAdjustmentDelay)
{
previousDelayElapsed =
delayHelper.HasBlockingAdjustmentDelayElapsed(currentTimeMs, wasSignaledToWake);
if (pendingBlockingAdjustment == PendingBlockingAdjustment.WithDelayIfNecessary &&
!previousDelayElapsed)
{
break;
}
}
uint nextDelayMs = threadPoolInstance.PerformBlockingAdjustment(previousDelayElapsed);
if (nextDelayMs <= 0)
{
delayHelper.ClearBlockingAdjustmentDelay();
}
else
{
delayHelper.SetBlockingAdjustmentTimeAndDelay(currentTimeMs, nextDelayMs);
}
} while (false);
//
// Periodic gate activities
//
if (!delayHelper.ShouldPerformGateActivities(currentTimeMs, wasSignaledToWake))
{
continue;
}
if (ThreadPool.EnableWorkerTracking && NativeRuntimeEventSource.Log.IsEnabled())
{
NativeRuntimeEventSource.Log.ThreadPoolWorkingThreadCount(
(uint)threadPoolInstance.GetAndResetHighWatermarkCountOfThreadsProcessingUserCallbacks());
}
int cpuUtilization = cpuUtilizationReader.CurrentUtilization;
threadPoolInstance._cpuUtilization = cpuUtilization;
bool needGateThreadForRuntime = ThreadPool.PerformRuntimeSpecificGateActivities(cpuUtilization);
if (!disableStarvationDetection &&
threadPoolInstance._pendingBlockingAdjustment == PendingBlockingAdjustment.None &&
threadPoolInstance._separated.numRequestedWorkers > 0 &&
SufficientDelaySinceLastDequeue(threadPoolInstance))
{
bool addWorker = false;
threadAdjustmentLock.Acquire();
try
{
// Don't add a thread if we're at max or if we are already in the process of adding threads.
// This logic is slightly different from the native implementation in CoreCLR because there are
// no retired threads. In the native implementation, when hill climbing reduces the thread count
// goal, threads that are stopped from processing work are switched to "retired" state, and they
// don't count towards the equivalent existing thread count. In this implementation, the
// existing thread count includes any worker thread that has not yet exited, including those
// stopped from working by hill climbing, so here the number of threads processing work, instead
// of the number of existing threads, is compared with the goal. There may be alternative
// solutions, for now this is only to maintain consistency in behavior.
ThreadCounts counts = threadPoolInstance._separated.counts;
if (counts.NumProcessingWork < threadPoolInstance._maxThreads &&
counts.NumProcessingWork >= threadPoolInstance._separated.numThreadsGoal)
{
if (debuggerBreakOnWorkStarvation)
{
Debugger.Break();
}
short newNumThreadsGoal = (short)(counts.NumProcessingWork + 1);
threadPoolInstance._separated.numThreadsGoal = newNumThreadsGoal;
HillClimbing.ThreadPoolHillClimber.ForceChange(
newNumThreadsGoal,
HillClimbing.StateOrTransition.Starvation);
addWorker = true;
}
}
finally
{
threadAdjustmentLock.Release();
}
if (addWorker)
{
WorkerThread.MaybeAddWorkingWorker(threadPoolInstance);
}
}
if (!needGateThreadForRuntime &&
threadPoolInstance._separated.numRequestedWorkers <= 0 &&
threadPoolInstance._pendingBlockingAdjustment == PendingBlockingAdjustment.None &&
Interlocked.Decrement(ref threadPoolInstance._separated.gateThreadRunningState) <= GetRunningStateForNumRuns(0))
{
break;
}
}
}
}