It's not a memory leak. You have to run sessions2trash.py periodically,
even if you're using Redis and setting and expiration time for every
session:
https://groups.google.com/g/web2py/c/IFjr-VQoyAE/m/VoihkT1NAgAJ
El lunes, 25 de julio de 2022 a la(s) 18:23:37 UTC-3, Lisandro escribió:
> I'm running web2py in production and I use a Redis server to store a
> couple of millons sessions, but I'm facing a memory problem that I haven't
> been able to fix.
>
> I use session_expiry=172800 (two days). The application load is very
> stable (it handles about 60 requests per second). I thought that after a
> few weeks running I would know how much memory I need for Redis. However
> the memory used by Redis keeps increasing indefinitely.
>
> I don't use sessions for anything more than a very small percentage of
> users that can login and do some administrative tasks. The vast majority of
> users can't login.
>
> Just in case, I checked and every key in redis has an expiration time:
> $ redis-cli info keyspace
> # Keyspace
> db0:keys=1549547,expires=1548249,avg_ttl=89380135
>
> I've also checked a few session keys and I saw that a session ocuppies
> about 250 bytes. However, the memory used by Redis grows slowly and
> constantly: in a whole year it reached the 24 gigabytes of RAM that the
> server has, which is insane, right?
>
> I had Redis configured to limit the amount of RAM it can use:
> maxmemory 20gb
> maxmemory-policy volatile-lru
>
> However, as I commented before, after a whole year it reached that limit,
> and my app started throwing this error:
>
> Traceback (most recent call last): File "/var/www/medios/gluon/main.py",
> line 462, in wsgibase session._try_store_in_db(request, response) File
> "/var/www/medios/gluon/globals.py", line 1226, in _try_store_in_db
> record_id = table.insert(**dd) File
> "/var/www/medios/gluon/contrib/redis_session.py", line 138, in insert newid
> = str(self.db.r_server.incr(self.serial)) File
> "/var/www/medios/venv_medios/lib/python2.7/site-packages/redis/client.py",
> line 651, in incr return self.execute_command('INCRBY', name, amount) File
> "/var/www/medios/venv_medios/lib/python2.7/site-packages/redis/client.py",
> line 394, in execute_command return self.parse_response(connection,
> command_name, **options) File
> "/var/www/medios/venv_medios/lib/python2.7/site-packages/redis/client.py",
> line 404, in parse_response response = connection.read_response() File
> "/var/www/medios/venv_medios/lib/python2.7/site-packages/redis/connection.py",
>
> line 316, in read_response raise response ResponseError: OOM command not
> allowed when used memory > 'maxmemory'.
>
>
> I thought that error was impossible giving that Redis has a maxmemory
> limit and it is instructed to evict keys when the limit is reached. However
> I realised that these types of scenarios (lot of keys being written and
> also lot of keys being deleted) can lead to memory fragmentation. And redis
> has a defragmentation option, so I made some changes.
>
> I reduced the maxmemory Redis limit and activated the auto defragmentation:
> maxmemory 1gb
> maxmemory-policy volatile-lru
> activedefrag yes
>
> Redis auto defragmentation works like a charm: when it wasn't active I
> could see that the mem_fragmentation_ratio was slowly increasing. After
> activating it, it stayed in a stable and optimal value of 1.05.
>
> After a week running (remember all the sessions expire in two days) Redis
> was using about 600mb of RAM. But the usage kept growing and reached the
> maxmemory limit a few days later.
> At that point, I could verify that Redis started evicting keys to make
> space (that was expected accordingly to the configuration).
> However a few days later my apps again started to throw the error with the
> exact same traceback I posted before :/
>
> What could be happening? I'm pretty sure that I don't need more than 1 or
> 2gb of RAM for handling the sessions with Redis. So why does it crash?
> Could it be a memory leak in gluon/contrib/redis_session.py adapter?
>
> One thing: I've never run sessions2trash.py
> But if I understand the documentation
> <http://web2py.com/books/default/chapter/29/13?search=cache#Sessions-in-Redis>
>
> right, I don't need to run it as I set an expiration time for every session.
>
> Let me know what you think, any help will be much appreciated.
> Thanks!
> Warm regards,
> Lisandro
>
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