How to dump status of jemalloc on Android

[Jason Evans]

On Jul 27, 2015, at 2:56 AM, LiHaifeng <omycle at gmail.com> wrote:
> It's known that the jemalloc is adopted by Android. Recently I want to dump some jemalloc status information with the thread exit. Fortunately, the function of status dump has been done by jemalloc.
> 
> After tuned the variable of opt_stats_print into true in malloc_init_hard(), the stats_print_atexit() was registered as an hook for atexit(). But, there is nothing status information dumped when the process exit and there is only the warning on the console like below.
> 
> "W/libc    (  859): WARNING: generic atexit() called from legacy shared library"
> 
> So, how to dump the jemalloc status on Android?

There appears to have been some change to glibc within the past two years that causes stdin/stdout/stderr to be closed before atexit-registered functions run.  To work around this you can directly call malloc_stats_print() directly in your application before it exits.  I ran into this a few days ago on an Ubuntu 15.04 system, and found this related bug report while trying to diagnose the issue:

	https://code.google.com/p/address-sanitizer/issues/detail?id=263

Jason