Re: Cannot allocate memory

Hi,

I would like to come back to you about my memory problem on postgres 12.

We had the same configuration under postgres 11.8, we disabled JIT (enabled by default under postgres 12) for segfault problems.

To illustrate the change in memory behavior, here is a screenshot before / after migration :

Do you have any idea what could change the behavior in this way? another parameter enabled by default under postgres 12 like JIT?

Regards.

Hi Community,

I'm asking for your lights because i'm having memory problems with postgres.

Examples of logs :

FATAL: could not fork new process for connection: Cannot allocate memory could not fork new process for connection: Cannot allocate memory
out of memory  DETAIL:  Failed on request of size 32800 in memory context "HashBatchContext".
out of memory DETAIL Failed on request of size 288 in memory context "CacheMemoryContext".


We use postgresql (primary/standby) with pgbouncer as a pooler, and repmgr as replication manager.

We have ~ 2000 connections at the same time with ~ 20/30 are active. (we need to set a high number of connexion on postgres, because our app uses a lot of different users, and each user on each app server needs multiple and constant connexions).

Here is my configuration :

system :
Debian : 9.13
Memory : 380 Go
Postgres : 12.4-1.pgdg90+1
Pgbouncer : 1.14
kernel.shmmax = 202591600640
kernel.shmall = 49460840

postgres :

dynamic_shared_memory_type = posix    # the default is the first option
max_connections = 2600            # (change requires restart)
work_mem = 96MB                # min 64kB
maintenance_work_mem = 8GB        # min 1MB
shared_buffers = 64GB            # min 128kB
temp_buffers = 32MB            # min 800kB
wal_buffers = 16MB            # min 32kB, -1 sets based on shared_buffers
effective_cache_size = 270GB

pgbouncer :

max_client_conn = 6000
default_pool_size = 2590
reserve_pool_size = 5
pool_mode = session

Do you think that our parameters are not correct compared to our configuration? Do you have an idea ?

Best regards.

Michael.