Re: [PATCH] malloc: Use correct C11 atomics for fastbin

[DJ Delorie <dj@redhat.com>]

Zack Weinberg via Libc-alpha <libc-alpha@sourceware.org> writes:
> Every time we start talking about fastbins vs tcache again I start 
> wondering, again, what's stopping us from replacing the entire malloc 
> implementation with jemalloc,

There's a couple of things, but they're technical details, not political
ones:

* There's a copy of a "mini-malloc" in the dynamic loader that needs to
  be somewhat compatible with the full copy in libc.so so that data
  allocated in the loader can be used later.

* The current malloc knows a lot about glibc internals like pthreads and
  fork, so as to manage those boundaries properly (thread start/stop,
  etc).

* Benchmarks have shown that the various mallocs each have their strong
  points and weak points, so expect some complaints about performance
  loss when switching mallocs.  Your favorite allocator may perform
  poorly in someone else's favorite application.

* Testing, testing, testing.  Libc's malloc is used in all Linux distros
  *and* Hurd, which means it's known to work with tens if not hundreds of
  thousands of programs.  To propose a new system-wide allocator, you
  need to replicate this level of effective testing.

> or any other implementation designed less than 20 years ago.

Comments like this are not appreciated.  Age does not imply quality.
Please stick to technical points.