High CPU usage during idle time due to GC
We have a web application using happstack. It always used ~1% CPU, which was fine. Recently, we started caching more things in memory, and CPU usage during idle time rose to 15-30%. We eventually determined this was due to the idle time GC (we compile with -threaded). Using +RTS -I2 removed the problem.
This is similar to #3408 (closed), except that that says it is fixed in 6.12, and that the interval is set to 5s. The docs [1] still mention 0.3s, though, and since changing it to 2s fixes our problem, it seems it's not 5s by default.
It is difficult to attach a simple test case, but I can test things if needed.
[1] http://www.haskell.org/ghc/docs/6.12.2/html/users_guide/runtime-control.html#rts-options-gc
Trac metadata
Trac field | Value |
---|---|
Version | 6.12.3 |
Type | Bug |
TypeOfFailure | OtherFailure |
Priority | normal |
Resolution | Unresolved |
Component | Runtime System |
Test case | |
Differential revisions | |
BlockedBy | |
Related | |
Blocking | |
CC | |
Operating system | |
Architecture |