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Avoid atexit(3) when possible, disable prof_final by default.

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atexit(3) can deadlock internally during its own initialization if
jemalloc calls atexit() during jemalloc initialization.  Mitigate the
impact by restructuring prof initialization to avoid calling atexit()
unless the registered function will actually dump a final heap profile.

Additionally, disable prof_final by default so that this land mine is
opt-in rather than opt-out.

This resolves #144.
This commit is contained in:
Jason Evans 2014-10-08 17:57:19 -07:00
parent 3a8b9b1fd9
commit 57efa7bb0e
4 changed files with 26 additions and 14 deletions
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18
doc/jemalloc.xml.in
View File

@ -857,8 +857,14 @@ for (i = 0; i < nbins; i++) {
<option>--enable-stats</option> is specified during configuration, this
has the potential to cause deadlock for a multi-threaded process that
exits while one or more threads are executing in the memory allocation
functions. Therefore, this option should only be used with care; it is
primarily intended as a performance tuning aid during application
functions. Furthermore, <function>atexit<parameter/></function> may
allocate memory during application initialization and then deadlock
internally when jemalloc in turn calls
<function>atexit<parameter/></function>, so this option is not
univerally usable (though the application can register its own
<function>atexit<parameter/></function> function with equivalent
functionality). Therefore, this option should only be used with care;
it is primarily intended as a performance tuning aid during application
development. This option is disabled by default.</para></listitem>
</varlistentry>
@ -1155,7 +1161,13 @@ malloc_conf = "xmalloc:true";]]></programlisting>
<filename>&lt;prefix&gt;.&lt;pid&gt;.&lt;seq&gt;.f.heap</filename>,
where <literal>&lt;prefix&gt;</literal> is controlled by the <link
linkend="opt.prof_prefix"><mallctl>opt.prof_prefix</mallctl></link>
option. This option is enabled by default.</para></listitem>
option. Note that <function>atexit<parameter/></function> may allocate
memory during application initialization and then deadlock internally
when jemalloc in turn calls <function>atexit<parameter/></function>, so
this option is not univerally usable (though the application can
register its own <function>atexit<parameter/></function> function with
equivalent functionality). This option is disabled by
default.</para></listitem>
</varlistentry>
<varlistentry id="opt.prof_leak">

17
src/prof.c
View File

@ -20,7 +20,7 @@ bool opt_prof_thread_active_init = true;
size_t opt_lg_prof_sample = LG_PROF_SAMPLE_DEFAULT;
ssize_t opt_lg_prof_interval = LG_PROF_INTERVAL_DEFAULT;
bool opt_prof_gdump = false;
bool opt_prof_final = true;
bool opt_prof_final = false;
bool opt_prof_leak = false;
bool opt_prof_accum = false;
char opt_prof_prefix[
@ -1487,17 +1487,17 @@ prof_fdump(void)
char filename[DUMP_FILENAME_BUFSIZE];
cassert(config_prof);
assert(opt_prof_final);
assert(opt_prof_prefix[0] != '\0');
if (!prof_booted)
return;
tsd = tsd_fetch();
if (opt_prof_final && opt_prof_prefix[0] != '\0') {
malloc_mutex_lock(&prof_dump_seq_mtx);
prof_dump_filename(filename, 'f', VSEQ_INVALID);
malloc_mutex_unlock(&prof_dump_seq_mtx);
prof_dump(tsd, false, filename, opt_prof_leak);
}
malloc_mutex_lock(&prof_dump_seq_mtx);
prof_dump_filename(filename, 'f', VSEQ_INVALID);
malloc_mutex_unlock(&prof_dump_seq_mtx);
prof_dump(tsd, false, filename, opt_prof_leak);
}
void
@ -2023,7 +2023,8 @@ prof_boot2(void)
if (malloc_mutex_init(&prof_dump_mtx))
return (true);
if (atexit(prof_fdump) != 0) {
if (opt_prof_final && opt_prof_prefix[0] != '\0' &&
atexit(prof_fdump) != 0) {
malloc_write("<jemalloc>: Error in atexit()\n");
if (opt_abort)
abort();

2
test/unit/prof_active.c
View File

@ -2,7 +2,7 @@
#ifdef JEMALLOC_PROF
const char *malloc_conf =
"prof:true,prof_thread_active_init:false,lg_prof_sample:0,prof_final:false";
"prof:true,prof_thread_active_init:false,lg_prof_sample:0";
#endif
static void

3
test/unit/prof_thread_name.c
View File

@ -1,8 +1,7 @@
#include "test/jemalloc_test.h"
#ifdef JEMALLOC_PROF
const char *malloc_conf =
"prof:true,prof_active:false,prof_final:false";
const char *malloc_conf = "prof:true,prof_active:false";
#endif
static void