Datanode active connections never returns to 0
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Key: HADOOP-2341
URL: https://issues.apache.org/jira/browse/HADOOP-2341
Project: Hadoop
Issue Type: Bug
Components: dfs
Affects Versions: 0.16.0
Reporter: Paul Saab
On trunk i continue to see the following in my data node logs:
2007-12-03 15:46:47,696 DEBUG dfs.DataNode - XX.XX.XX.XXX:50010:Number of
active connections is: 42
2007-12-03 15:46:48,135 DEBUG dfs.DataNode - XX.XX.XX.XXX:50010:Number of
active connections is: 41
2007-12-03 15:46:48,439 DEBUG dfs.DataNode - XX.XX.XX.XXX:50010:Number of
active connections is: 40
2007-12-03 15:46:48,479 DEBUG dfs.DataNode - XX.XX.XX.XXX:50010:Number of
active connections is: 39
2007-12-03 15:46:48,611 DEBUG dfs.DataNode - XX.XX.XX.XXX:50010:Number of
active connections is: 38
2007-12-03 15:46:48,898 DEBUG dfs.DataNode - XX.XX.XX.XXX:50010:Number of
active connections is: 37
2007-12-03 15:46:48,989 DEBUG dfs.DataNode - XX.XX.XX.XXX:50010:Number of
active connections is: 36
2007-12-03 15:46:51,010 DEBUG dfs.DataNode - XX.XX.XX.XXX:50010:Number of
active connections is: 35
2007-12-03 15:46:51,758 DEBUG dfs.DataNode - XX.XX.XX.XXX:50010:Number of
active connections is: 34
2007-12-03 15:46:52,148 DEBUG dfs.DataNode - XX.XX.XX.XXX:50010:Number of
active connections is: 33
This number never returns to 0, even after many hours of no new data being
manipulated or added into the DFS.
Looking at netstat -tn i see significant amount of data in the send-q that
never goes away:
tcp 0 34240 ::ffff:XX.XX.XX.XXX:50010 ::ffff:YY.YY.YY.YY:55792
ESTABLISHED
tcp 0 38968 ::ffff:XX.XX.XX.XXX:50010 ::ffff:YY.YY.YY.YY:38169
ESTABLISHED
tcp 0 38456 ::ffff:XX.XX.XX.XXX:50010 ::ffff:YY.YY.YY.YY:35456
ESTABLISHED
tcp 0 29640 ::ffff:XX.XX.XX.XXX:50010 ::ffff:YY.YY.YY.YY:59845
ESTABLISHED
tcp 0 50168 ::ffff:XX.XX.XX.XXX:50010 ::ffff:YY.YY.YY.YY:44584
ESTABLISHED
When sniffing the network I see that the remote side (YY.YY.YY.YY) is returning
a window size of 0
16:11:41.760474 IP XX.XX.XX.XXX.50010 > YY.YY.YY.YY.44584: . ack 3339984123 win
46 <nop,nop,timestamp 1786247180 885681789>
16:11:41.761597 IP YY.YY.YY.YY.44584 > XX.XX.XX.XXX.50010: . ack 1 win 0
<nop,nop,timestamp 885801786 1775711351>
Then we look at the stack traces on each datanode, I will have tons of threads
that *never* go away in the following trace:
{code}
Thread 6516 ([EMAIL PROTECTED]):
State: RUNNABLE
Blocked count: 0
Waited count: 0
Stack:
java.net.SocketOutputStream.socketWrite0(Native Method)
java.net.SocketOutputStream.socketWrite(SocketOutputStream.java:92)
java.net.SocketOutputStream.write(SocketOutputStream.java:136)
java.io.BufferedOutputStream.flushBuffer(BufferedOutputStream.java:65)
java.io.BufferedOutputStream.write(BufferedOutputStream.java:109)
java.io.DataOutputStream.write(DataOutputStream.java:90)
org.apache.hadoop.dfs.DataNode$BlockSender.sendChunk(DataNode.java:1400)
org.apache.hadoop.dfs.DataNode$BlockSender.sendBlock(DataNode.java:1433)
org.apache.hadoop.dfs.DataNode$DataXceiver.readBlock(DataNode.java:904)
org.apache.hadoop.dfs.DataNode$DataXceiver.run(DataNode.java:849)
java.lang.Thread.run(Thread.java:619)
{code}
Unfortunately there's very little in the logs with exceptions that could point
to this. I have some exceptions the following, but nothing that points to
problems between XX and YY:
{code}
2007-12-02 11:19:47,889 WARN dfs.DataNode - Unexpected error trying to delete
block blk_4515246476002110310. Block not found in blockMap.
2007-12-02 11:19:47,922 WARN dfs.DataNode - java.io.IOException: Error in
deleting blocks.
at org.apache.hadoop.dfs.FSDataset.invalidate(FSDataset.java:750)
at org.apache.hadoop.dfs.DataNode.processCommand(DataNode.java:675)
at org.apache.hadoop.dfs.DataNode.offerService(DataNode.java:569)
at org.apache.hadoop.dfs.DataNode.run(DataNode.java:1720)
at java.lang.Thread.run(Thread.java:619)
{code}
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