NC 23 upgrade crashes php-fpm > server reached pm.max_children setting (10), consider raising it

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Upgrade NC to version 23.0.0 (Beta channel)

The issue you are facing:

PHP-PFM crashed with segfault. a restart of php resolves the issue

Is this the first time you’ve seen this error? No

Steps to replicate it:

  1. I had php configured with the standard values: for pm.max_children = 5
    /etc/php/7.4/fpm/pool.d/www.conf
  2. log in to NC, and click on the Picture tab, then NC goes off and renders the thumbnail. After about 20 images, the php process crashed
  • this has worked fine before for about 9 months!
  1. Workaround: pm.max_children = 80 (and others values increased)

The output of your Nextcloud log in Admin > Logging:

nothing..

The output of your config.php file in /path/to/nextcloud (make sure you remove any identifiable information!):

default configuration

The output of your Apache/nginx/system log in /var/log/____:

nothing
1 Like
2

Do you get more information regarding the segfault? How many images are in a folder, are there thousands of thumbnails created?

On less powerful machines, the generation can be a problem. There is a nice post about the preview generation for raspberry pi: Understanding and improving Nextcloud Previews – Own your bits

3

Many thanks for your reply.
I run a AMD Ryzen 5 2400G with 32GB of RAM, so not really a RasPI like machine.

There could have been a “large” maybe hundreds of images (sycing my mobile) in a single folder.

The main problem seams to be that for each thumbnail, a new php thread is created, and this kind of kills php! (which in my opinion should not).
maybe Nextcloud should have a max-concurrent-thumbnail creator value.

the strange thing is that this has worked fine for the last year, and just since the upgrade to NC23.0.0.0 the problem started.

I see if I can get a segfault
roman

4

I got the same problem when upgrading to 23.0.0 docker image. It keeps crashing with segfault. I have a folder with a lot of images too.

5

Solution:

on my 32GB server I changed these values in the file:
/etc/php/7.4/fpm/pool.d/www.conf
to:

pm.max_children = 128

; The number of child processes created on startup.
; Note: Used only when pm is set to ‘dynamic’
; Default Value: (min_spare_servers + max_spare_servers) / 2
; 15
pm.start_servers = 32

; The desired minimum number of idle server processes.
; Note: Used only when pm is set to ‘dynamic’
; Note: Mandatory when pm is set to ‘dynamic’
; 15
pm.min_spare_servers = 32

; The desired maximum number of idle server processes.
; Note: Used only when pm is set to ‘dynamic’
; Note: Mandatory when pm is set to ‘dynamic’
; 8
pm.max_spare_servers = 96

This will create a lot more tasks on the server, but it’s now stable. Also these numbers are kind of reflecting the size of memory which the application can use. Never the less, I’m a single person using Nextcloud! so I’m not sure if this is the right way, for a large installation. And this only happend after the upgrade to v23!

roman

6

You have 32GB of RAM. Use it! :wink:

The pm.max_children value is probably still a bit low, given the amount of RAM you have in your server.

Found this article, which might be helpful:

Personally I use the calculation from C. Riegers guide. Nextcloud 23 Installationsanleitung mit Apache2 - Carsten Rieger IT-Services which lead to the following values on my server with 8GB of RAM:

pm.max_children = 281
pm.start_servers = 140
pm.min_spare_servers = 93
pm.max_spare_servers = 187
2 Likes
7

It’s not working for me, I’m using nextcloud:23.0.0 docker images, which I believe is build on apache. And I changed the config at /usr/local/etc/php/conf.d/nextcloud.ini (there is no folder under /etc/php/7.4/fpm/pool.d/www.conf) and it is still showing segmentation fault.

app_1    | Initializing nextcloud 23.0.0.10 ...
app_1    | Upgrading nextcloud from 22.2.3.0 ...
app_1    | Segmentation fault (core dumped)
app_1    | Segmentation fault (core dumped)
nextcloud_app_1 exited with code 139
app_1    | Initializing nextcloud 23.0.0.10 ...
app_1    | Upgrading nextcloud from 22.2.3.0 ...
app_1    | Segmentation fault (core dumped)
app_1    | Segmentation fault (core dumped)
app_1    | Initializing nextcloud 23.0.0.10 ...
app_1    | Upgrading nextcloud from 22.2.3.0 ...
app_1    | Segmentation fault (core dumped)
app_1    | Segmentation fault (core dumped)
app_1    | Initializing nextcloud 23.0.0.10 ...
app_1    | Upgrading nextcloud from 22.2.3.0 ...
app_1    | Segmentation fault (core dumped)
app_1    | Segmentation fault (core dumped)
nextcloud_app_1 exited with code 139
8

On a bare metal Ubuntu installation the config files for PHP-FPM are in a separate directory, and the values have to be added to the www.conf file, not to the php.ini. Unfortunately I can’t tell you what the corresponding paths and files in the Docker container are, because I don’t use it…

9

Hi Guys,

I run a Ubuntu 20.04 LTS:

The path of the www.conf file is here:
sudo nano /etc/php/7.4/fpm/pool.d/www.conf

then you need to restart the service.

roman

10

for those using docker fpm here’s what you can add

command: >-
      sh -c '
        {
          echo pm=dynamic;
          echo pm.max_children=120;
          echo pm.start_servers=12;
          echo pm.min_spare_servers=6;
          echo pm.max_spare_servers=18;
        } >> /usr/local/etc/php-fpm.d/www.conf;
        exec /entrypoint.sh php-fpm
      '

see example: Updates fix reached children limit by lastlink · Pull Request #19 · lastlink/nextcloud-docker-ml-example · GitHub