Integration with Symfony - memory leak

[rmikalkenas]

Hi all!

Recently I started playing around RoadRunner and so far I'm impressed with all the capabilities it provides:)
While working with vanilla php examples everything works fine and the memory consumption is stable across multiple http requests.
But lately tried to run fresh Symfony installation and faced increasing memory between http requests. At first I thought it's because of custom php extensions I have locally (Xdebug and Datadog), but removing them didn't help. Afterwards I tried to execute gc_collect_cycles(); after each request - the memory became stable, but overall performance degraded.

Curious is it expected behavior using Symfony framework and is gc_collect_cycles(); the best approach for solving memory leaks..?
Maybe someone had similar issues and could guide me how to properly configure RR to use with Symfony?

Reproduced for memory leak: https://github.com/rmikalkenas/roadrunner-leak-reproducer
My local env:

rr -v               
rr version 2.12.2 (build time: 2023-01-12T12:07:45+0000, go1.19.5), OS: linux, arch: amd64

php -v
PHP 8.1.14 (cli) (built: Jan 11 2023 08:10:46) (NTS)
Copyright (c) The PHP Group
Zend Engine v4.1.14, Copyright (c) Zend Technologies
    with Zend OPcache v8.1.14, Copyright (c), by Zend Technologies

[rustatian]

Hey, @rmikalkenas 👋🏻 Nice to meet you, thanks for using RoadRunner ❤️

Have you tried ./rr workers -i ? How did you measure memory consumption?

[rustatian]

I guess it's better to ask the author of this integration: https://github.com/Baldinof/roadrunner-bundle. You may also uncomment this section: https://github.com/rmikalkenas/roadrunner-leak-reproducer/blob/master/.rr.yaml#L34 and double check the memory consumption via ./rr workers -i command. But also, I don't think that gc_collect_cycles(); is expected behavior.

[rmikalkenas]

Some interesting findings:
rr workers -i indicates a stable memory consuption of 42MB (even on more than 50k+ execs) - so it's great!
But memory_get_usage(); shows fluctuating memory usage:
I did 10k requests, after each memory_get_usage(); increases, but once it reaches ~14MB it drops to ~5MB.. Looks like somebody is clearing the memory. To minimize impact of Baldinof/roadrunner-bundle I removed it completely and manually implemented worker based on docs example. The result was exactly the same. So the only assumption that comes to my mind is that php has some kind of additional GC clearing policy which is based on memory consumption.

[rustatian]

Basically, ./rr workers -i works like a supervisor and shows the correct RSS memory usage (because it is obtained from your OS). I'm not a PHP, so, that's hard for me to say, what's happening inside the PHP and what method to use, but I guess this is the PHP GC. It might be you need to check the memory_limit in your php.ini.

[wolfy-j]

memory_get_usage() shows memory allocated by PHP and it's affected by GC. So it's OK for it to drop, use RR memory metrics (see above) for a RSS usage which includes engine memory. That's more reliable way.

[rmikalkenas]

Appreciate for the help! Marked discussion as answered