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. 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? -- Thomas Munro https://enterprisedb.com
