Re: Thread synchronization

"Alexander Grigoriev" <>
Thu, 18 Oct 2007 19:58:47 -0700
No No! Don't use ResetEvent, especially in the consumer thread.

Use auto-reset events.

With ResetEvent you can have a race condition, and your consumer thread may
not get awaken in time.

Auto-reset event works as a reliable signal from producer to consumer, to
wake up and smell the roses, oops, to check the buffer.

"Scott McPhillips [MVP]" <org-dot-mvps-at-scottmcp> wrote in message

If I understand correctly, you want a reading thread to pause when the
writing index and reading index of a circular buffer are at certain
difference limits. I think you can do that with logic that uses a critical
section and a manual reset event. Inside the critical section the writing
thread can write to the queue, update the write index, and test the
difference between indexes to decide if reading is OK. It would SetEvent
to permit reading, or ResetEvent when no reading should occur. Then it
exits from the critical section.

The reading thread would call WaitForSingleObject on the event. When that
returns enter the critical section, test the indexes to see if it is still
OK to read, and if so read the queue and update the reading index, then
exit the critical section. If the reading thread finds that it is not OK
to read it should reset the event and return from the critical section.
That will stop the reading thread from further reading until the writing
thread sets the event again.

Good Luck.

Scott McPhillips [VC++ MVP]

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