On Thu, Apr 11, 2019 at 12:48:35PM +1200, Thomas Munro wrote: > On Mon, Apr 8, 2019 at 6:42 PM Noah Misch <n...@leadboat.com> wrote: > > - AIX animals failed two ways. First, I missed a "use" statement such that > > poll_start() would fail if it needed more than one attempt. Second, I > > assumed $pid would be gone as soon as kill(9, $pid) returned[1]. > > > [1] POSIX says "sig or at least one pending unblocked signal shall be > > delivered to the sending thread before kill() returns." I doubt the > > postmaster had another signal pending often enough to explain the failures, > > so > > AIX probably doesn't follow POSIX in this respect. > > It looks like you fixed this, but I was curious about this obversation > as someone interested in learning more about kernel stuff and > portability... Maybe I misunderstood, but isn't POSIX referring to > kill(sig, $YOUR_OWN_PID) there? That is, if you signal *yourself*, > and no other thread exists that could handle the signal, it will be > handled by the sending thread, and in the case of SIGKILL it will > therefore never return. But here, you were talking about a perl > script that kills the postmaster, no? If so, that passage doesn't > seem to apply.
You're right. I revoke the footnote. > In any case, regardless of whether the signal handler > has run to completion when kill() returns, doesn't the pid have to > continue to exist in the process table until it is reaped by its > parent (possibly in response to SIGCHLD), with one of the wait*() > family of system calls? True. I'll add that to the code comment.
