[jira] [Resolved] (ACCUMULO-4777) Root tablet got spammed with 1.8 million log entries
[ https://issues.apache.org/jira/browse/ACCUMULO-4777?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ] Ivan Bella resolved ACCUMULO-4777. -- Resolution: Fixed Commits put into branches 1.7, 1.8, and 2.0 > Root tablet got spammed with 1.8 million log entries > > > Key: ACCUMULO-4777 > URL: https://issues.apache.org/jira/browse/ACCUMULO-4777 > Project: Accumulo > Issue Type: Bug >Affects Versions: 1.8.1 >Reporter: Ivan Bella >Assignee: Ivan Bella >Priority: Critical > Labels: pull-request-available > Fix For: 1.7.4, 1.9.0, 2.0.0 > > Time Spent: 6h > Remaining Estimate: 0h > > We had a tserver that was handling accumulo.metadata tablets that somehow got > into a loop where it created over 22K empty wal logs. There were around 70 > metadata tablets and this resulted in around 1.8 million log entries in added > to the accumulo.root table. The only reason it stopped creating wal logs is > because it ran out of open file handles. This took us many hours and cups of > coffee to clean up. > The log contained the following messages in a tight loop: > log.TabletServerLogger INFO : Using next log hdfs://... > tserver.TabletServfer INFO : Writing log marker for hdfs://... > tserver.TabletServer INFO : Marking hdfs://... closed > log.DfsLogger INFO : Slow sync cost ... > ... > Unfortunately we did not have DEBUG turned on so we have no debug messages. > Tracking through the code there are three places where the > TabletServerLogger.close method is called: > 1) via resetLoggers in the TabletServerLogger, but nothing calls this method > so this is ruled out > 2) when the log gets too large or too old, but neither of those checks should > have been hitting here. > 3) In a loop that is executed (while (!success)) in the > TabletServerLogger.write method. In this case when we unsuccessfullty write > something to the wal, then that one is closed and a new one is created. This > loop will go forever until we successfully write out the entry. A > DfsLogger.LogClosedException seems the most logical reason. This is most > likely because a ClosedChannelException was thrown from the DfsLogger.write > methods (around line 609 in DfsLogger). > So the root cause was most likely hadoop related. However in accumulo we > probably should not be doing a tight retry loop around a hadoop failure. I > recommend at a minimum doing some sort of exponential back off and perhaps > setting a limit on the number of retries resulting in a critical tserver > failure. -- This message was sent by Atlassian JIRA (v7.6.3#76005)
[jira] [Resolved] (ACCUMULO-4777) Root tablet got spammed with 1.8 million log entries
[ https://issues.apache.org/jira/browse/ACCUMULO-4777?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ] Ivan Bella resolved ACCUMULO-4777. -- Resolution: Fixed > Root tablet got spammed with 1.8 million log entries > > > Key: ACCUMULO-4777 > URL: https://issues.apache.org/jira/browse/ACCUMULO-4777 > Project: Accumulo > Issue Type: Bug >Affects Versions: 1.8.1 >Reporter: Ivan Bella >Assignee: Ivan Bella >Priority: Critical > Labels: pull-request-available > Fix For: 1.7.4, 1.9.0, 2.0.0 > > Time Spent: 3h 10m > Remaining Estimate: 0h > > We had a tserver that was handling accumulo.metadata tablets that somehow got > into a loop where it created over 22K empty wal logs. There were around 70 > metadata tablets and this resulted in around 1.8 million log entries in added > to the accumulo.root table. The only reason it stopped creating wal logs is > because it ran out of open file handles. This took us many hours and cups of > coffee to clean up. > The log contained the following messages in a tight loop: > log.TabletServerLogger INFO : Using next log hdfs://... > tserver.TabletServfer INFO : Writing log marker for hdfs://... > tserver.TabletServer INFO : Marking hdfs://... closed > log.DfsLogger INFO : Slow sync cost ... > ... > Unfortunately we did not have DEBUG turned on so we have no debug messages. > Tracking through the code there are three places where the > TabletServerLogger.close method is called: > 1) via resetLoggers in the TabletServerLogger, but nothing calls this method > so this is ruled out > 2) when the log gets too large or too old, but neither of those checks should > have been hitting here. > 3) In a loop that is executed (while (!success)) in the > TabletServerLogger.write method. In this case when we unsuccessfullty write > something to the wal, then that one is closed and a new one is created. This > loop will go forever until we successfully write out the entry. A > DfsLogger.LogClosedException seems the most logical reason. This is most > likely because a ClosedChannelException was thrown from the DfsLogger.write > methods (around line 609 in DfsLogger). > So the root cause was most likely hadoop related. However in accumulo we > probably should not be doing a tight retry loop around a hadoop failure. I > recommend at a minimum doing some sort of exponential back off and perhaps > setting a limit on the number of retries resulting in a critical tserver > failure. -- This message was sent by Atlassian JIRA (v7.6.3#76005)
