/*++
* @name ExpCheckDynamicThreadCount
*
* The ExpCheckDynamicThreadCount routine checks every queue and creates a
* dynamic thread if the queue seems to be deadlocked.
*
* @param None
*
* @return None.
*
* @remarks The algorithm for deciding if a new thread must be created is
* based on wether the queue has processed no new items in the last
* second, and new items are still enqueued.
*
*--*/
VOID
NTAPI
ExpDetectWorkerThreadDeadlock(VOID)
{
ULONG i;
PEX_WORK_QUEUE Queue;
/* Loop the 3 queues */
for (i = 0; i < MaximumWorkQueue; i++)
{
/* Get the queue */
Queue = &ExWorkerQueue[i];
ASSERT(Queue->DynamicThreadCount <= 16);
/* Check if stuff is on the queue that still is unprocessed */
if ((Queue->QueueDepthLastPass) &&
(Queue->WorkItemsProcessed == Queue->WorkItemsProcessedLastPass) &&
(Queue->DynamicThreadCount < 16))
{
/* Stuff is still on the queue and nobody did anything about it */
DPRINT1("EX: Work Queue Deadlock detected: %d\n", i);
ExpCreateWorkerThread(i, TRUE);
DPRINT1("Dynamic threads queued %d\n", Queue->DynamicThreadCount);
}
/* Update our data */
Queue->WorkItemsProcessedLastPass = Queue->WorkItemsProcessed;
Queue->QueueDepthLastPass = KeReadStateQueue(&Queue->WorkerQueue);
}
}
VOID
ExpDetectWorkerThreadDeadlock (
VOID
)
/*++
Routine Description:
This function creates new work item threads if a possible deadlock is
detected.
Arguments:
None.
Return Value:
None
--*/
{
ULONG Index;
PEX_WORK_QUEUE Queue;
PAGED_CODE();
//
// Process each queue type.
//
for (Index = 0; Index < MaximumWorkQueue; Index += 1) {
Queue = &ExWorkerQueue[Index];
ASSERT( Queue->DynamicThreadCount <= MAX_ADDITIONAL_DYNAMIC_THREADS );
if ((Queue->QueueDepthLastPass > 0) &&
(Queue->WorkItemsProcessed == Queue->WorkItemsProcessedLastPass) &&
(Queue->DynamicThreadCount < MAX_ADDITIONAL_DYNAMIC_THREADS)) {
//
// These things are known:
//
// - There were work items waiting in the queue at the last pass.
// - No work items have been processed since the last pass.
// - We haven't yet created the maximum number of dynamic threads.
//
// Things look like they're stuck, create a new thread for this
// queue.
//
// We explicitly ignore an error from ExpCreateDynamicThread():
// we'll try again in another detection period if the queue looks
// like it's still stuck.
//
ExpCreateWorkerThread (Index, TRUE);
}
//
// Update some bookkeeping.
//
// Note that WorkItemsProcessed and the queue depth must be recorded
// in that order to avoid getting a false deadlock indication.
//
Queue->WorkItemsProcessedLastPass = Queue->WorkItemsProcessed;
Queue->QueueDepthLastPass = KeReadStateQueue (&Queue->WorkerQueue);
}
}
