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https://issues.apache.org/jira/browse/KYLIN-2862?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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liyang resolved KYLIN-2862.
---------------------------
Resolution: Fixed
Fix Version/s: v2.2.0
> BasicClientConnManager in RestClient can't do well with syncing many query
> severs
> ---------------------------------------------------------------------------------
>
> Key: KYLIN-2862
> URL: https://issues.apache.org/jira/browse/KYLIN-2862
> Project: Kylin
> Issue Type: Bug
> Components: General
> Affects Versions: v2.1.0
> Reporter: Fangyuan Deng
> Assignee: Fangyuan Deng
> Fix For: v2.2.0
>
> Attachments: KYLIN-2862.0.patch, KYLIN-2862.1.patch
>
>
> In KYLIN-2814 , it fixs some kinds of sync wipe fails.
> After we use this patch , sync wipe fails still often happen, the log is
> like this.
> 2017-09-08 21:28:13,029 WARN [pool-10-thread-2] cachesync.Broadcaster:137 :
> Thread failed during wipe cache at BroadcastEvent{entity=cube, event=update,
> cacheKey=olap_nh_log_all_di_cube}, error msg:
> java.lang.IllegalStateException: Invalid use of BasicClientConnManager:
> connection still allocated.
> Make sure to release the connection before allocating another one.
> We search the code, then we found , the DefaultHttpClient uses
> BasicClientConnManager as default ConnManager.
> and the BasicClientConnManager is a simple connection manager that maintains
> only one connection at a time. Even though this class is thread-safe it ought
> to be used by one execution thread only.
> if we have many query servers, the BasicClientConnManager will be
> bottleneck.
> so we use PoolingClientConnectionManager instead, which can manages a pool
> of client connections and is able to service connection requests from
> multiple execution threads.
> Then everything goes fine. the code is below
> final PoolingClientConnectionManager cm = new
> PoolingClientConnectionManager();
> cm.setDefaultMaxPerRoute(20);
> cm.setMaxTotal(200);
> client = new DefaultHttpClient(cm, httpParams);
> see more about BasicClientConnManager and PoolingClientConnectionManager
> http://hc.apache.org/httpcomponents-client-ga/tutorial/html/connmgmt.html#d5e619
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