On Jan 19 17:21, Corinna Vinschen wrote: > On Jan 19 11:38, Corinna Vinschen wrote: > > On Jan 19 08:29, SCOTT Damien wrote: > > > [...] > > > I have included a simplified version of my code below. I usually > > > don't see any evidence of the SIGUSR1 signal being received by either > > > of the listener threads. Occasionally the first thread unblocks as > > > expected but I have never seen both threads unblock. If I change my > > > code so that there is only a single listener thread, then everything > > > works correctly every time. Changing the msgrcv() call to a sleep > > > call also allows unblocking to occur correctly. Note that this > > > simplified code does not include removal of the created queues (since > > > it never manages to exit anyway) so I manually remove these after each > > > run using the ipcrm command. > > > > > > Example output: > > > > > > Running thread 2 with queue Id = 1441792 > > > Running thread 1 with queue Id = 1179649 > > > About to kill thread 1 > > > > > > Is there an issue with the Cygwin implementation of signal handling, > > > or is there a problem with my code? Any help would be much > > > appreciated. > > > > It's an issue with the Cygwin code, probably. The msgrcv code ultimately > > hangs in a blocking ReadFile call on a named pipe, and this call is > > non-interruptible. Changing that requires a bigger change in Cygwin > > which will take time. > > ...or not. I'm not sure I can fix that for the upcoming 1.7.34 release, > but it seems cygserver is using the wrong signal handle. At one point > the signal handling got changed a lot to improve per-thread signalling, > and, as far as I can see, the cygserver code still assumes a global > per-process signal handle, which is the old version from before the > change. > > Just to let you know I'm looking into that. Stay tuned. > > Oh, btw., there's a bug in your testcase: > > int id = msgget(key, IPC_CREAT|IPC_EXCL); > > This call is missing the permission bits, so the permissions are set > to 000. The permission bits should be added: > > int id = msgget(key, IPC_CREAT|IPC_EXCL|S_IWUSR|S_IRUSR);
Well, it was not as complicated as I anticipated. I applied a patch to cygserver to pull it into the wonderful modern times of per-thread signalling. I created and uploaded a new developer snapshot to https://cygwin.com/snapshots/ with this change. Please give it a try and report back. Thanks, Corinna -- Corinna Vinschen Please, send mails regarding Cygwin to Cygwin Maintainer cygwin AT cygwin DOT com Red Hat
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