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    SubjectRe: [PATCH][RFC] Pollable /proc/<pid>/ - avoid SIGCHLD/poll() races
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    On Sat, 13 Oct 2001 17:36:19 +0200, Jamie Lokier
    <lk@tantalophile.demon.co.uk> wrote:

    >Mattias Engdegård wrote:
    >> I don't think it's contrived --- writing not a byte, but the pid and
    >> return status of the dead child to a pipe is an old but useful trick.
    >> It gives a natural serialisation of child deaths, and also eliminates
    >> the common race where a child dies before its parent has recorded its
    >> pid in a data structure. See it as a safe way of converting an
    >> asynchronous signal to a queued event.
    >>
    >> Using pipes to wake up blocking select()s is a useful thing in general,
    >> and often a lot cleaner than using signals when dealing with threads.
    >
    >This mistake is exactly the reason that Netscape 4.x freezes from time
    >to time on Linux.
    >
    >It tries to write too many things to a pipe, making the assumption that
    >this will never happen.

    At one point a few years ago, someone implemented a loadable library
    which "fixed" the Netscape problem by knowing what the bug was, doing
    things the right way, and presenting the interface Netscape expected.

    john
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