Re: Official Linux system wrapper library?

* Adam Borowski:

On Sun, Nov 11, 2018 at 12:46:35PM +0100, Florian Weimer wrote:

quoted

A lot of multi-threaded applications assume that most high-level
functionality remains usable even after fork in a multi-threaded
process.

How would this be even possible?  Currently fork kills all threads
(save for the caller).

glibc's fork acquires several locks around fork.  Other mallocs install
fork handlers, too.

Glibc's manpage also warns:

# After a fork() in a multithreaded program, the child can safely call only
# async-signal-safe functions (see signal-safety(7)) until such time as it
# calls execve(2).

Which makes sense as its malloc uses a mutex, and you can't take a breath
without a library call using malloc somewhere (or in C++, the language
itself).

Right, but applications require a working malloc after fork,
unfortunately.  opendir is often used to enumerate file descriptors
which need closing, for example.

Thanks,
Florian