Re: Problem with locks

"Gregory Stark" <stark(at)enterprisedb(dot)com> writes:

> "Gregory Stark" <stark(at)enterprisedb(dot)com> writes:
>
>> "Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us> writes:
>>
>>> Gregory Stark <stark(at)enterprisedb(dot)com> writes:
>>>> We're seeing a problem where occasionally a process appears to be granted a
>>>> lock but miss its semaphore signal.
>>>
>>> Kernel bug maybe? What's the platform?

I've written a synthetic test program to check for lost semaphore wakeups. I
can't seem to produce any on my machine but haven't had a chance to run it yet
on the benchmark machine that's been showing the problem.

If I can't produce any lost wakeups with a program like this it looks more
like it might be a Postgres or GCC bug than a Linux bug.

It would be helpful if people could run this on various architectures and
various versions of Linux (or other OSes). I've been running it with 40
processes for an hour, but even shorter runs would be useful. It will drive
the load on your machine through the roof but doesn't cause any i/o.

$ gcc -Wall ipctest.c -lrt
$ ./a.out 40 3600