Imagemagick memory allocation failed

[nikkuexe]

When generation previews of larger images, Imagemagick can run into an error: convert-im6.q16: memory allocation failed

Expanding the allowed memory in the policy file would allow larger image files to have previews generated:

/etc/ImageMagick-6/policy.xml

  <policy domain="resource" name="area" value="256MB"/>
  <policy domain="resource" name="memory" value=“1GiB"/>
  <policy domain="resource" name="map" value=“2GiB"/>
  <policy domain="resource" name="disk" value=“4GiB"/>

It may be appropriate for the IM policy to be customized based on the system it runs on, since some servers may be resource limited.

[nikkuexe]

The default imagemagick policy.xml is fairly conservative. It's not meant for handling larger image files that Nextcloud is often used for. A similar Cache resources exhausted error is also related to the policy.xml settings.

Some resources:

https://legacy.imagemagick.org/discourse-server~/viewtopic13c6.html?p=172497#p172497

https://github.com/ImageMagick/ImageMagick/issues/396#issuecomment-326849298

https://stackoverflow.com/a/53699200

[girish]

It seems the defaults are:

  <policy domain="resource" name="memory" value="256MiB"/>
  <policy domain="resource" name="map" value="512MiB"/>
  <policy domain="resource" name="width" value="16KP"/>
  <policy domain="resource" name="height" value="16KP"/>
  <!-- <policy domain="resource" name="list-length" value="128"/> -->
  <policy domain="resource" name="area" value="128MB"/>
  <policy domain="resource" name="disk" value="1GiB"/>

[nikkuexe]

The default imagemagick policy.xml is fairly conservative. It's not meant for handling larger image files that Nextcloud is often used for. A similar Cache resources exhausted error is also related to the policy.xml settings.

Some resources:

https://legacy.imagemagick.org/discourse-server~/viewtopic13c6.html?p=172497#p172497

https://github.com/ImageMagick/ImageMagick/issues/396#issuecomment-326849298

https://stackoverflow.com/a/53699200

[girish]

@nikkuexe I have adjusted it here - https://git.cloudron.io/cloudron/nextcloud-app/-/commit/e7dc56f0fad6bbade59aede429b3ff34096e96b9

[nikkuexe]

@girish It works. Thanks for the update.

[nikkuexe]

@girish
I should mention that on certain systems, Nextcloud's preview generation can push ImageMagick to consume all the cpu resources, freezing the frontend.

To ensure that ImageMagick never hinders Nextcloud, I would recommend these policy changes:

  <policy domain="resource" name="thread" value="1"/>
  <policy domain="resource" name="throttle" value="100"/> 

The first line limits IM to use only one CPU thread. The second line has IM give at least 100ms to other CPU tasks so it's never taking 100% of the CPU.

[girish]

@nikkuexe thanks. Applied the patch here https://git.cloudron.io/cloudron/nextcloud-app/-/commit/1886a32f4d15724cfc3af74fbc0f07772ccba13b