Re: [rt.cpan.org #73747] signal handlers don't work while waiting

Fri Jan 06 23:51:32 2012: Request 73747 was acted upon.
Transaction: Correspondence added by [email protected]
       Queue: Win32-IPC
     Subject: Re: [rt.cpan.org #73747] signal handlers don't work while waiting
   Broken in: (no value)
    Severity: (no value)
       Owner: Nobody
  Requestors: [email protected]
      Status: stalled
 Ticket <URL: https://rt.cpan.org/Ticket/Display.html?id=73747 >


I've tried everything I could think of, but was not successful in getting
the signal handler to work while perl was sitting inside the
WaitForSingleObject, inside of ipc code.

However, I was able to work around the issue by utilizing threads - if I
spin up a perl thread and do the change notify in it, and detach this
thread from the main thread, both the change notify blocking functionality
works, and the signal handler works.

I can use condition variables to signal the change in the directory to the
main thread.

So, this isn't really a fix, just a workaround, but I wonder where I can
post this little titbit of knowledge.

On Wed, Jan 4, 2012 at 4:54 PM, Christopher J. Madsen via RT <
[email protected]> wrote:

> <URL: https://rt.cpan.org/Ticket/Display.html?id=73747 >
>
> The behavior I see with Windows XP and Perl 5.14.2 is this: if a signal
> handler is active, it's not called until the wait completes (because a
> notification happens or it times out).  I'm not clear whether you're
> seeing the same thing.
>
> I believe this is because of Perl's deferred signal handling:
> http://perldoc.perl.org/perlipc.html#Deferred-Signals-%28Safe-Signals%29
>
> I agree that's probably not the most desirable behavior, but I don't
> know how to change it.  I'd welcome a pull request
> (https://github.com/madsen/win32-ipc) if you have a solution.
>