Re: [PATCH] nextfd(2)

[Colin Walters]

On Mon, 2012-04-02 at 16:17 -0700, KOSAKI Motohiro wrote:

> we can only call async-signal-safe functions after fork() when multi threads and
> opendir() call malloc() internally.
> 
> As far as I know, OpenJDK has a such fork-readdir-exec code and it can
> make deadlock
> when spawnning a new process. Unfortunately Java language perfeter to
> make a lot of threads rather than other language.
> 
> This patch can solve such multi threaded case.
> 
> offtopic, glibc malloc is a slightly clever. It reinitialize its
> internal lock when fork by
> using thread_atfork() hook. It mean glibc malloc can be used after
> fork() and the
> technique can avoid this issue. 

Yeah, a *lot* of code out there depends on this glibc malloc
implementation detail.  We uncovered our dependency on this in
GNOME a while back while investigating getenv/setenv/fork and threads:
https://bugzilla.gnome.org/show_bug.cgi?id=659326


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