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Hadoop QA commented on HADOOP-9956: ----------------------------------- {color:green}+1 overall{color}. Here are the results of testing the latest attachment http://issues.apache.org/jira/secure/attachment/12613204/HADOOP-9956.patch against trunk revision . {color:green}+1 @author{color}. The patch does not contain any @author tags. {color:green}+1 tests included{color}. The patch appears to include 1 new or modified test files. {color:green}+1 javac{color}. The applied patch does not increase the total number of javac compiler warnings. {color:green}+1 javadoc{color}. The javadoc tool did not generate any warning messages. {color:green}+1 eclipse:eclipse{color}. The patch built with eclipse:eclipse. {color:green}+1 findbugs{color}. The patch does not introduce any new Findbugs (version 1.3.9) warnings. {color:green}+1 release audit{color}. The applied patch does not increase the total number of release audit warnings. {color:green}+1 core tests{color}. The patch passed unit tests in hadoop-common-project/hadoop-common. {color:green}+1 contrib tests{color}. The patch passed contrib unit tests. Test results: https://builds.apache.org/job/PreCommit-HADOOP-Build/3272//testReport/ Console output: https://builds.apache.org/job/PreCommit-HADOOP-Build/3272//console This message is automatically generated. > RPC listener inefficiently assigns connections to readers > --------------------------------------------------------- > > Key: HADOOP-9956 > URL: https://issues.apache.org/jira/browse/HADOOP-9956 > Project: Hadoop Common > Issue Type: Sub-task > Components: ipc > Affects Versions: 2.0.0-alpha, 3.0.0 > Reporter: Daryn Sharp > Assignee: Daryn Sharp > Attachments: HADOOP-9956.patch, HADOOP-9956.patch > > > The socket listener and readers use a complex synchronization to update the > reader's NIO {{Selector}}. Updating active selectors is not thread-safe so > precautions are required. > However, the current locking choreography results in a serialized > distribution of new connections to the parallel socket readers. A > slower/busier reader can stall the listener and throttle performance. > The problem manifests as unexpectedly low cpu utilization by the listener and > readers (~20-30%) under heavy load. The call queue is shallow when it should > be overflowing. -- This message was sent by Atlassian JIRA (v6.1#6144)