zhengchenyu created YARN-5964:
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Summary: fairscheduler use too many object lock, leads to low
performance
Key: YARN-5964
URL: https://issues.apache.org/jira/browse/YARN-5964
Project: Hadoop YARN
Issue Type: Improvement
Components: fairscheduler
Affects Versions: 2.7.1
Environment: CentOS-7.1
Reporter: zhengchenyu
Priority: Critical
Fix For: 2.7.1
When too many applications are running, we found that client couldn't submit
the application, and a high callqueuelength of port 8032. I catch the jstack of
resourcemanager when callqueuelength is too high. I found that the thread "IPC
Server handler xxx on 8032" are waitting for the object lock of FairScheduler,
nodeupdate holds the lock of the FairScheduler. Maybe high process time leads
to the phenomenon that client can't submit the application.
Here I don't consider the problem that client can't submit the application,
only estimates the performance of the fairscheduler. We can see too many
function which needs object lock are used, the granularity of object lock is
too big. For example, nodeUpdate and getAppWeight wanna hold the same object
lock. It is unresonable and inefficiency. I recommand that the low granularity
lock replaces the current lock.
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