Hi,
We had similar issues with asterisk just continually using more and more
memory, switched from standard glibc malloc() to tcmalloc, and in cases
where memory usage (RSS) would go from 200MB to >8GB in a day it now
runs stable at around 400MB.
Probably won't be as severe in the case of mariadb, but memory
fragmentation is an issue, and more fragments, the harder the allocators
job becomes which then also starts to degrade in terms of CPU
performance (more work per alloc/de-alloc due to larger structures to
traverse).
Kind regards,
Jaco
On 2025/03/17 14:13, Derick Turner via discuss wrote:
Thanks for the response Sergie!
I switched over to jemalloc in an effort to try and resolve the issue
- as I had seen some posts suggesting that as a potential option to
deal with memory leaks. I've removed this from one of the servers
which has set it back to system. On the next rotation of restarts I'll
change another to tmalloc, so I can track any differences between the
three.
In case this is also related: we do not get any instances in the logs
for InnoDB: Memory pressure events. The listener is being started on
all instances. I'm assuming this is where the memory in the InnoDB
cache is being released back to the OS? There were logged instances
of this running when all of the memory was consumed and the system was
starting to use swap. However, OOM killer eventually kicked in and
killed the DB process, which is too much of a risk for us to have
happen at the moment.
Kind regards
Derick
On 17/03/2025 11:55, Sergei Golubchik wrote:
Hi, Derick,
According to your SHOW GLOBAL STATUS
Memory_used 15460922288
That is the server thinks it uses about 15GB
The difference could be due to memory fragmentation, when the server
frees the memory, but it cannot be returned to the OS. In this case
using a different memory allocator could help (try system or tcmalloc).
Regards,
Sergei
Chief Architect, MariaDB Server
and [email protected]
On Mar 17, Derick Turner via discuss wrote:
Hi all,
I was pointed to this list from a question I raised on StackExchange
(https://dba.stackexchange.com/questions/345743/why-does-my-mariadb-application-use-more-memory-than-configured)
I have a cluster of MariaDB (11.4.5) primary/primary servers running on
Ubuntu. I updated the OS on Saturday to 24.04 from 22.04 (and patched
the DB to the 11.4.5 noble version) as we were occasionally hitting an
OOM event which was causing the database process to be killed. Since
then, the DB process takes all of the available server memory before
being killed by the OOM killer.
DB is configured to use about 15GB of RAM (from config calculations)
Servers currently have 50GB of RAM and 95% of this is used within about
an hour an a half.
Link to document with configuration settings, global status,
mariadb.service override and InnoDB status is here -
https://docs.google.com/spreadsheets/d/1ev9KRWP8l54FpRrhFeX4uxFhJnOlFkV4_vTCZWipcXA/edit?usp=sharing
Any help would be gratefully received.
Thanks in advance.
Derick
--
Derick Turner - He/Him
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