From: Elad Lahav <e2lahav@gmail.com>
To: perfbook@vger.kernel.org
Subject: 7.5.2.7: Library Functions Used Between fork() and exec()
Date: Fri, 14 Oct 2022 08:14:42 -0400 [thread overview]
Message-ID: <CAJbg=FU6Sa=vc6DRGsewXMP6N1Hz2HHUsKkgNTUzPx9Bh0VuKQ@mail.gmail.com> (raw)
Ah, multi-threaded fork, my arch-nemesis.
A few points, though I'm not sure any of these are worth mentioning in the book:
1. It should perhaps be made clear that the child's copy of the lock
is, in fact, a separate lock. The statement that the lock is held by a
parent thread is somewhat inaccurate. That is, unless the lock is in
explicitly-shared memory (i.e., the result of mmap(MAP_SHARED)), in
which case the lock is indeed the same and is (presumably) meant to be
shared between the parent and child.
2. POSIX explicitly says that you can't execute any
non-async-signal-safe functions between fork() and exec(), which
pretty much eliminates any function that acquires a lock.
3. posix_spawn() is a safer alternative to the fork()/exec() pair
(though not to fork() by itself), at least with sensible
implementations that don't devolve to fork() and exec().
--Elad
next reply other threads:[~2022-10-14 12:15 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-14 12:14 Elad Lahav [this message]
2022-10-19 23:32 ` 7.5.2.7: Library Functions Used Between fork() and exec() Paul E. McKenney
2022-10-19 23:51 ` Elad Lahav
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