Subj : Linux 2.4: sigwait() not getting SIGTERM
To   : comp.programming.threads
From : Clint Olsen
Date : Mon Feb 14 2005 12:37 pm

Hi:

We've got a threaded application and a rather strange problem with
pthreads.

The application itself spins off a thread which monitors signals received
so that it can respond to them in a synchronous fashion.  All threads are
set to block on SIGTERM (and quite a few other signals), and it then goes
into sigwait().  It *does* successfully receive SIGINT, however SIGTERM
never makes it.

What's really odd is that when we track down the thread that's doing the
sigwait() and send it a SIGTERM directly, the signal is received!
Furthermore, we can send a signal to the entire process group and this also
seems to work as expected.

For grins, here's the process tree that results from the application:

foo(18233)---foo(18286)-+-foo(18287)
                        |-foo(18288)
                        |-foo(18289)
                        `-foo(18290)

In our case the signal waiting thread is 18287.

My apologies if this has been seen before.  I did some Googling and did not
get any relevant hits.

Thanks,

-Clint

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