FS notification watch aggregator stuck spinning on timers ("CPU Usage High with no mission") #9927
Description
What happened?
I encountered this issue on both v1.20 and v1.27.7. Currently, the situation is that I don't have any tasks (there might have been some in the past, but at least right now there are no tasks), and CPU usage randomly spikes to very high levels. At this point, restarting syncthing resolves the issue, but whether it will reoccur or how long it will take to appear is uncertain.
This is the pprof I captured：
cpu pprof
heap pprof
This is the top output:
flat flat% sum% cum cum%
8130ms 20.71% 20.71% 8130ms 20.71% math.archExp
7710ms 19.64% 40.35% 7710ms 19.64% runtime.memclrNoHeapPointers
3730ms 9.50% 49.85% 3980ms 10.14% math.log1p
1310ms 3.34% 53.18% 3970ms 10.11% runtime.scanobject
1240ms 3.16% 56.34% 1240ms 3.16% math.archLog
1160ms 2.95% 59.30% 16150ms 41.14% github.com/greatroar/blobloom.fpRate
590ms 1.50% 60.80% 2340ms 5.96% github.com/greatroar/blobloom.logPoisson
540ms 1.38% 62.18% 810ms 2.06% runtime.findObject
530ms 1.35% 63.53% 530ms 1.35% runtime.(*mspan).base (inline)
490ms 1.25% 64.77% 490ms 1.25% runtime.futexSyncthing version
v1.27.7
Platform & operating system
Linux amd64 Debian
Browser version
Safari, Chrome