Synthing opens a ton of threads to a point of resource exhaustion

Support
1

I’m seeing Synthing opening a ton of threads when scanning a directory. It’s an ever-growing list of threads:

syncthing@ansible1:/$ ps -eLf | grep 'yncthing'  | wc -l
4523

My data dir is a JuiceFS Mount — not sure if that’s relevant.

I’ve set the config to limit resource usage. Copiers and hashers set to 1. copy_file_range enabled. maxConcurrentIncomingRequestKiB set to 32768. pullerMaxPendingKiB set to 16384. progressUpdateIntervalS set to -1. numConnections set to 1.

The list of threads just constantly grows it looks like maybe some jobs aren’t closed once they’re done?

Any help diagnosing the issue is greatly appreciated

2

What Syncthing version are you running?

3

Taking a support bundle would help clarify what’s going on.

4 
syncthing v1.29.5 "Gold Grasshopper" (go1.24.2 linux-amd64) debian@debian 2025-04-20 21:21:27 UTC
5

I think you should try upgrading to the newest version of Syncthing 2.x and see what happens there first. Your version comes from April 2025, so it’s quite outdated, and lot has changed in the code since then.