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From "Geoff Hendrey" <ghend...@decarta.com>
Subject FW: Put slows down and eventually blocks
Date Wed, 19 May 2010 21:12:39 GMT
Sorry for the cross-post. Just wanted to make sure I addressed my
question to the currently active mailing list. (see question below)


From: Geoff Hendrey 
Sent: Tuesday, May 18, 2010 11:56 PM
To: hbase-user@hadoop.apache.org
Subject: Put slows down and eventually blocks

I am experiencing a problem in which Put operations transition from
working just fine, to blocking forever. I am doing Put from a reducer. I
have tried the following, but none of them prevents the Puts from
eventually blocking totally in all the reducers, until the task tracker
kills the task due to 10 minute timeout.
1) try using just one reducer (didn't help)
2) try Put.setWriteToWall both true and false (didn't help)
3) try autoflush true and false. When true, experiment with different
flush buffer sizes (didn't help)
I'v been watching the HDFS namenode and datanode logs, and also the
HBase master and region servers. I am running a 3-node HDFS cluster
(20.2) sharing same 3 nodes with HBase 20.3. I see no problems in any
logs, except that the datanode logs eventually stop showing WRITE
operations (corresponding to the Put operations eventually coming to a
halt). The HBase shell remains snappy and I can do list and status
operations and scans without any issue from the shell.
Anyone ever seen anything like this?




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