B20.1: Returning from pause() before signal handler runs?

Chris Faylor cgf@cygnus.com
Wed Mar 31 19:45:00 GMT 1999

On Thu, Mar 25, 1999 at 02:02:53PM +0000, Richard.Hirst@net-tel.co.uk wrote:
>  I am running "sendmail -q1" under B20.1 on NT4.0 SP3.  This should poll a
>queue directory once a minute, but I find that after a few polls it goes to
>sleep.  I have provided a small test program which shows the problem.
>The parent installs ALRM and CHLD signal handlers, forks a child,
>requests an alarm tick., and calls pause().  The child exits.  Sometimes
>the child exits before the parent calls pause(), sometimes not.  The
>signal handlers increment counts each time they run.  The parent notes
>these counts before calling pause, and again after returning from pause().
>Sometimes the parent finds that the counts havn't changed; it does a
>printf() and checks the counts again - now they have changed.
>It looks to me as though the parent is returning from pause() before
>the signal handler has been run.  
>I can provoke the problem within a few cycles if I run a couple of
>copies of the program and then start up a few other programs (DevStudio,
>MSDOS boxes, etc).  This is on a PII-233 with 64MB, NT4.0 SP3.
>If anyone could reproduce the problem, and say whether it looks like
>a cygwin bug or not, I'd appreciate it.

Looking at the code, it does appear to be a bug.  I've fixed the problem
and it will be in the next snapshot.


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