SUMMARY: Decreasing semaphores for debugging

From: Stuart Whitby (
Date: Fri Jul 30 1999 - 09:55:07 CDT

I didn't get any answers on this question, so I did some experimenting.

It seems that the default values in Solaris are rather low, at least as
far as Oracle is concerned. However, it's only apps which use threaded
processes which need semaphores - ruling out 95% of the apps in use at
this time.

As such, decreasing the values by a factor of 10 did an okay job of
debugging. That should completely stuff an app which needs semaphores,
but makes no difference (in my case at least) to the running of the
O/S. It seemed like a good idea at the time, but made no difference
in my case. Which was as much debugging of semaphores as I needed.

One other useful command that I found with relation to this and hadn't
seen before - sysdef. Check it out for kernel settings.


Stuart Whitby.

Original question:


I'm currently at a customer site (which is why I'm
writing from a Yahoo address) trying to debug a problem
with crashing software.

The software runs for a while, and grinds slowly to a
halt. I think there's a good chance that it's not
freeing up semaphores properly, and the O/S runs out.
I don't want to wait overnight for this problem to
occur again though, so I'd like to reduce the available
semaphores to a point where the O/S can run and there
are just enough free for processes. That way, it
should fail much sooner. Can anyone recommend some
values for this?

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