[HACKERS] Anyone interested in improving postgresql scaling?

Tom Lane tgl at sss.pgh.pa.us
Tue Apr 10 21:36:20 UTC 2007

Kris Kennaway <kris at obsecurity.org> writes:
> I have not studied the exact code path, but there are indeed multiple
> wakeups happening from the semaphore code (as many as the number of
> active postgresql processes).  It is easy to instrument
> sleepq_broadcast() and log them when they happen.

There are certainly cases where Postgres will wake up a number of
processes in quick succession, but that should happen from a separate
semop() kernel call, on a different semaphore, for each such process.
If there's really multiple processes being released by the same semop()
then there's a bug we need to look into (or maybe it's a kernel bug?).
Anyway I'd be interested to know what the test case is, and which PG
version you were testing.

			regards, tom lane

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