# Cannot request additional shared memory outside shmem\_request\_hook

**URL:** <https://forums.percona.com/t/cannot-request-additional-shared-memory-outside-shmem-request-hook/23444>\
**Category:** pg\_stat\_monitor\
**Created:** [July 7, 2023, 12:35pm UTC](https://forums.percona.com/t/cannot-request-additional-shared-memory-outside-shmem-request-hook/23444 "2023-07-07T12:35:55Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![khaled\_ghazy](https://sea1.discourse-cdn.com/flex019/user_avatar/forums.percona.com/khaled_ghazy/32/11532_2.png) [@khaled\_ghazy](https://forums.percona.com/u/khaled_ghazy)\
**Post date:** [July 7, 2023, 12:35pm UTC](https://forums.percona.com/t/cannot-request-additional-shared-memory-outside-shmem-request-hook/23444/1 "2023-07-07T12:35:55Z")

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I have PostgreSQL 15.3. Then I install pg\_stat\_monitor. Then when I restart the database, it can’t start with this error:

```auto
-- Unit postgresql-15.service has begun starting up.
Jun 20 13:58:12 PostgresqlDB01 postmaster[1864274]: 2023-06-20 13:58:12.997 EEST [1864274] LOG: pgaudit extension initialized
Jun 20 13:58:13 PostgresqlDB01 postmaster[1864274]: 2023-06-20 13:58:12.998 EEST [1864274] FATAL: cannot request additional shared memory outside shmem_request_hook
Jun 20 13:58:13 PostgresqlDB01 postmaster[1864274]: 2023-06-20 13:58:12.998 EEST [1864274] LOG: database system is shut down
Jun 20 13:58:13 PostgresqlDB01 systemd[1]: postgresql-15.service: Main process exited, code=exited, status=1/FAILURE
Jun 20 13:58:13 PostgresqlDB01 systemd[1]: postgresql-15.service: Failed with result 'exit-code'.

```

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<div class="post-metadata">

**Author:** ![khaled\_ghazy](https://sea1.discourse-cdn.com/flex019/user_avatar/forums.percona.com/khaled_ghazy/32/11532_2.png) [@khaled\_ghazy](https://forums.percona.com/u/khaled_ghazy)\
**Post date:** [July 7, 2023, 12:45pm UTC](https://forums.percona.com/t/cannot-request-additional-shared-memory-outside-shmem-request-hook/23444/2 "2023-07-07T12:45:42Z")

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what is the solution for this problem ?

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**Author:** ![Robert\_Bernier](https://sea1.discourse-cdn.com/flex019/user_avatar/forums.percona.com/robert_bernier/32/1367_2.png) [@Robert\_Bernier](https://forums.percona.com/u/Robert_Bernier)\
**Post date:** [July 7, 2023, 1:43pm UTC](https://forums.percona.com/t/cannot-request-additional-shared-memory-outside-shmem-request-hook/23444/3 "2023-07-07T13:43:12Z")

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Hi,

> what is the solution for this problem ?

Ah, this problem crops up from time to time when postgres demands OS resources that are not available. pg\_stat\_monitor isn’t the only use case that can cause this problem, increasing the maximun number of connections is a common cause of this issue too.

There are two solutions:

- Not ideal: reduce the number of maximum connections, freeing up kernel resources.
- Increase kernel resources

Here’s a couple of reference URLs that I hope can help you out:

- [here](https://unix.stackexchange.com/questions/265428/extremely-high-shmem-usage)
- [here](https://www.postgresql.org/docs/current/kernel-resources.html)
- The CLI administering kernel resources is [sysctl](https://man7.org/linux/man-pages/man8/sysctl.8.html)

Hope this helps.

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<div class="post-metadata">

**Author:** ![khaled\_ghazy](https://sea1.discourse-cdn.com/flex019/user_avatar/forums.percona.com/khaled_ghazy/32/11532_2.png) [@khaled\_ghazy](https://forums.percona.com/u/khaled_ghazy)\
**Post date:** [July 21, 2023, 1:36pm UTC](https://forums.percona.com/t/cannot-request-additional-shared-memory-outside-shmem-request-hook/23444/4 "2023-07-21T13:36:02Z")

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> [@Robert\_Bernier](#):
>
> sources

thanks for your information ,  
but which parameter kernel should i edit it ?  
and max connection for me is default 100