[
https://issues.apache.org/jira/browse/MAPREDUCE-3944?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13222518#comment-13222518
]
Robert Joseph Evans commented on MAPREDUCE-3944:
------------------------------------------------
I forgot to address Vinod's question about where the LRU is happening.
loadedJobCache, which holds a mapping between JobId and the CompletedJob is an
instance of LinkedHashMap which I believe removes the least recently used entry
when expungeEldest returns true. I could be wrong about that, it may just
remove the entry that has been in the list the longest.
> JobHistory web services are slower then the UI and can easly overload the JH
> ----------------------------------------------------------------------------
>
> Key: MAPREDUCE-3944
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-3944
> Project: Hadoop Map/Reduce
> Issue Type: Bug
> Components: mrv2
> Affects Versions: 0.23.1, 0.23.2
> Reporter: Robert Joseph Evans
> Assignee: Robert Joseph Evans
> Priority: Blocker
>
> When our first customer started using the Job History web services today the
> History Server ground to a halt. We found 250 Jetty threads stuck on the
> following stack trace.
> {noformat}
> java.lang.Thread.State: BLOCKED (on object monitor)
> at
> org.apache.hadoop.mapreduce.v2.hs.JobHistory.getJob(JobHistory.java:898)
> - waiting to lock <0x00002aaab364ba60> (a
> org.apache.hadoop.mapreduce.v2.hs.JobHistory)
> at
> org.apache.hadoop.mapreduce.v2.hs.webapp.HsWebServices.getJobs(HsWebServices.java:188)
> {noformat}
> HsWebServices.java:188 corresponds to the /mapreduce/jobs service.
> Looking at the code there are a number of optimizations that need to be done
> to improve its performance.
--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators:
https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa
For more information on JIRA, see: http://www.atlassian.com/software/jira
