idle GC causes large CPU usage if run more frequently than 1 second
I have a web server which exhibits unusual CPU usage. When it first starts it loads a bunch of state from disk -- around 800MB. It then sits idle consuming no CPU. If I make any request to the server, it starts using 30-60% of the CPU and never goes back down -- even if the request does not interact with the state system at all.
If I disable idle GC, then the problem goes away. If I set idle GC time using, +RTS -I1
, the problem goes away. If I set it to, +RTS -I0.9999999
, then I see the CPU usage issue.
Setting the +RTS -I1
option is sufficient for now, but the documentation says I should report any weirdness.
I do not have a simple test case for this.
Trac metadata
Trac field | Value |
---|---|
Version | 6.10.4 |
Type | Bug |
TypeOfFailure | OtherFailure |
Priority | normal |
Resolution | Unresolved |
Component | Runtime System |
Test case | |
Differential revisions | |
BlockedBy | |
Related | |
Blocking | |
CC | |
Operating system | |
Architecture |