STAT/LaunchMON occasionally hangs
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- Dominant language
- C++
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- 13
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Description
As noted #43, @lee218llnl: reported.
1.
> Occasionally I get hangs with STAT, particularly after running it multiple times. It appears to be in lmon__fe.cxx on line 4601 in a pthread_cond_timedwait. I don’t know if this is an actual affect or just a correlation, but it seems like if I subsequently attach TV to the job and detach TV, then I am able to attach again with STAT.
2.
> I have also seen hang-like behavior (looping) in cobo on cobo_connect_hostname. This also appears to happen if I aggressively attach/detach/attach STAT multiple times.
I suspect 1 is due to FIFO handling within `jsrun` but I need a simple reproducer to prove or disprove myself.
I suspect 2 is due to a problem with colocation service within `jsrun`, but I need a simple reproducer to prove or disprove myself.
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Research direction
Start by reproducing repeated STAT attach/detach/attach operations and inspect lmon__fe.cxx around line 4601, where pthread_cond_timedwait may hang. Also investigate looping in cobo_connect_hostname and compare the behavior with jsrun FIFO handling and colocation service; done means identifying and preventing the hang or loop with a simple reproducer.
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Assessment
- Tech stack
- cpp
- Domain
- hpc
- Issue type
- Bug
- Difficulty
- 5/5
- Estimated time
- Over a week
- Activity status
- Stale
- Clarity
- Needs clarification
- Newbie friendliness
- 25/100