On Jul 14 15:19, Houder wrote: > On Fri, 12 Jul 2019 17:33:51, Corinna Vinschen wrote: > > > On Jul 6 19:15, Kenton Varda wrote: > > > > I found a second problem which may or may not be related: > > > > If two threads use pthread_kill() to send each other the same signal, > > > such that the signal should be separately pending on both threads at > > > the same time, only one of the two signals is actually queued. It > > > seems that pthread_kill() is ignored if the same signal is already > > > pending on some other thread. > > > > The current signal mechanism in Cygwin only allows for a signal to be > > queued once. Changing that is a pretty ambitioned task, which I simply > > don't have enought time for. However, patches to change that are more > > than welcome. > > .. uhm, just a note in the interest of accuracy ... > > - standard signals (which include USRSIG1 and USRSIG2) are not queued > (traditional signal semantics) > - only real-time signals should be queued ... > > The executive (cygwin1.dll) must maintain a record of the signals that > are pending for the process as a whole, > as well as a record of the signals that are pending for each thread.
Yeah, the latter is missing so far. > A call to sigpending() returns the union of the set of signals that are > pending for the process > and those that are pending for the calling thread. > > Source: 33.2.1 (How the Unix Signal Model maps to threads) of LPI. > > Undoubtedly, the signal mechanism in Cygwin must be "adapted", but > as far as I can tell, there is no requirement to "queue" any of the > standard signals ... I think queing here means just what you outline above. It's kind of a queue of pending signals and in Cygwin it's actually literally a queue. Corinna -- Corinna Vinschen Cygwin Maintainer
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