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PSA: If your Jellyfin is having high memory usage, add MALLOC_TRIM_THRESHOLD_=100000 to environment (lemm.ee)
submitted 4 weeks ago* (last edited 4 weeks ago) by American_Jesus@lemm.ee to c/selfhosted@lemmy.world
14 comments fedilink hide all child comments

Many users reported high memory/RAM usage, some 8GB+.

In my case gone from 1.5GB+ to 400MB or less on Raspberry Pi 4.

Adding MALLOC_TRIM_THRESHOLD_=100000can make a big difference.

With Docker:
Add to your docker-compose.yml and docker compose down && docker compose up -d

...
environment:
  - MALLOC_TRIM_THRESHOLD_=100000
...

With systemd:
Edit /etc/default/jellyfin change the value of MALLOC_TRIM_THRESHOLD_ and restart the service

# Disable glibc dynamic heap adjustment
MALLOC_TRIM_THRESHOLD_=100000

Source: https://github.com/jellyfin/jellyfin/issues/6306#issuecomment-1774093928

Official docker,Debian,Fedora packages already contain MALLOC_TRIM_THRESHOLD_.
Not present on some docker images like linuxserver/jellyfin

Check is container (already) have the variable
docker exec -it jellyfin printenv | grep MALLOC_TRIM_THRESHO LD_

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[-] atzanteol@sh.itjust.works 80 points 4 weeks ago* (last edited 4 weeks ago)

It's bad form to just say "set this variable to this value" without any explanation about what that variable does and why that value helped.

Your configuration may not work or may be detrimental for others.

[-] TheButtonJustSpins@infosec.pub 6 points 4 weeks ago

If you click the source linked, you can read through all the details.

[-] aBundleOfFerrets@sh.itjust.works 10 points 4 weeks ago

The linked source also doesn’t explain what the env variable actually does or why it fixes anything.

[-] litchralee@sh.itjust.works 66 points 4 weeks ago

PS: Reddit doesn't allow edit post titles, needed to repost

But this is Lemmy.

[-] FauxLiving@lemmy.world 27 points 4 weeks ago

OP didn't update their repost bot to understand what it's reposting.

[-] enemenemu@lemm.ee 17 points 4 weeks ago

What does it do?

[-] American_Jesus@lemm.ee 23 points 4 weeks ago

The value of this tunable is the minimum size (in bytes) of the top-most, releasable chunk in an arena that will trigger a system call in order to return memory to the system from that arena.

https://www.gnu.org/software/libc/manual/html_node/Memory-Allocation-Tunables.html

MALLOC_MMAP_THRESHOLD_ is an environment variable that sets the size threshold for using the mmap system call to allocate memory instead of using the heap.

  • Default: 128 KiB
  • Behavior:
    • If a memory request is ≥ 128 KiB, mmap is used.
    • If < 128 KiB, the heap is used.
  • Purpose:
    • Helps manage large memory allocations more efficiently.
    • Can be adjusted to optimize performance for specific applications.
[-] BaroqueInMind@lemmy.one 6 points 4 weeks ago

What's the default value?

[-] American_Jesus@lemm.ee 3 points 4 weeks ago

It could depend on your distro, official packaging (docker,Debian,Fedora) have MALLOC_TRIM_THRESHOLD_=131072 , but different distros could have (or not) ship with different settings.

Official settings for systemd https://github.com/jellyfin/jellyfin-packaging/blob/master/debian/conf/jellyfin

[-] apprehensively_human@lemmy.ca 1 points 4 weeks ago

I've been having memory leak issues with my Jellyfin container, so I fired it up to see if it has a MALLOC variable set and it immediately crashed my server. Now waiting for the OOM killer to do its thing.

[-] TheButtonJustSpins@infosec.pub 1 points 4 weeks ago

Thank you for posting this! I've been increasing the memory for my VM over and over and it was using 24GB RAM + 4GB swap. Hopefully this will let me reclaim some.

[-] boreengreen@lemm.ee 0 points 4 weeks ago* (last edited 4 weeks ago)

How well does jellyfin work on a rpi? How many simultaneous 1080p users with AVC\ACC media can it do? Active cooling?

[-] Hiro8811@lemmy.world 2 points 4 weeks ago

Didn't try but depends on which RPI. 4? 5?

[-] sugar_in_your_tea@sh.itjust.works 1 points 4 weeks ago

Also depends on the storage medium (SD? SSD?), assuming there's no transcoding.

this post was submitted on 31 Mar 2025
101 points (92.4% liked)

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