Re: segfault runninng fio against 2048 jobs

[Jens Axboe <axboe@kernel.dk>]

On 2012-04-18 20:16, Roger Sibert wrote:
> Hello Jens,
> 
> Not sure if this is a red herring or not.
> 
> I did a quick check using valgrind with its memcheck on the 1 job sample
> and noted that there appears to be a small memory leak which gets
> noticeably worse when you run against a larger job configuration.
> 
> All the leaks appear to be the same originating line of code so just a
> snippet of the valgrind output is included below.
> 
> 1 job configuration file
> ==19277== 168 bytes in 1 blocks are definitely lost in loss record 9 of
> 10
> ==19277==    at 0x4A0610C: malloc (vg_replace_malloc.c:195)
> ==19277==    by 0x408A44: load_ioengine (ioengines.c:148)
> ==19277==    by 0x409BE2: ioengine_load (init.c:694)
> ==19277==    by 0x409F79: add_job (init.c:765)
> ==19277==    by 0x40BD26: parse_jobs_ini (init.c:1135)
> ==19277==    by 0x40C059: parse_options (init.c:1602)
> ==19277==    by 0x4082F3: main (fio.c:104)
> ==19277==
> .
> .
> ==19277==
> ==19277== LEAK SUMMARY:
> ==19277==    definitely lost: 211 bytes in 6 blocks
> ==19277==    indirectly lost: 0 bytes in 0 blocks
> ==19277==      possibly lost: 272 bytes in 1 blocks
> ==19277==    still reachable: 12 bytes in 3 blocks
> ==19277==         suppressed: 0 bytes in 0 blocks
> ==19277== Reachable blocks (those to which a pointer was found) are not
> shown.
> ==19277== To see them, rerun with: --leak-check=full
> --show-reachable=yes
> 
> 
> 2048 job configuration file.
> ==19365== 50,618,216 (311,144 direct, 50,307,072 indirect) bytes in
> 2,047 blocks are definitely lost in loss record 22 of 22
> ==19365==    at 0x4A0610C: malloc (vg_replace_malloc.c:195)
> ==19365==    by 0x42DA03: setup_log (iolog.c:499)
> ==19365==    by 0x40A9DD: add_job (init.c:846)
> ==19365==    by 0x40BD26: parse_jobs_ini (init.c:1135)
> ==19365==    by 0x40C059: parse_options (init.c:1602)
> ==19365==    by 0x4082F3: main (fio.c:104)
> ==19365==
> ==19365== LEAK SUMMARY:
> ==19365==    definitely lost: 1,843,954 bytes in 22,523 blocks
> ==19365==    indirectly lost: 201,154,560 bytes in 8,185 blocks
> ==19365==      possibly lost: 73,728 bytes in 3 blocks
> ==19365==    still reachable: 580 bytes in 4 blocks
> ==19365==         suppressed: 0 bytes in 0 blocks

Yes, there are a few minor leaks that could grow based on number of
jobs. But it's only really a concern if you run fio as a server backend,
otherwise it's nicely freed when the job is done. And it's not leaking
while a job is running either, it's "just" some of the initialization
memory that isn't freed explicitly on exit.


-- 
Jens Axboe