Jean-Daniel Cryans created HBASE-6240:
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Summary: Race in HCM.getMaster stalls clients
Key: HBASE-6240
URL: https://issues.apache.org/jira/browse/HBASE-6240
Project: HBase
Issue Type: Bug
Affects Versions: 0.94.0
Reporter: Jean-Daniel Cryans
Priority: Critical
Fix For: 0.94.1
I found this issue trying to run YCSB on 0.94, I don't think it exists on any
other branch. I believe that this was introduced in HBASE-5058 "Allow
HBaseAdmin to use an existing connection".
The issue is that in HCM.getMaster it does this recipe:
# Check if the master is null and runs (if so, return)
# Grab a lock on masterLock
# nullify this.master
# try to get a new master
The issue happens at 3, it should re-run 1 since while you're waiting on the
lock someone else could have already fixed it for you. What happens right now
is that the threads are all able to set the master to null before others are
able to get out of getMaster and it's a complete mess.
Figuring it out took me some time because it doesn't manifest itself right
away, silent retries are done in the background. Basically the first clue was
this:
{noformat}
Error doing get: org.apache.hadoop.hbase.client.RetriesExhaustedException:
Failed after attempts=10, exceptions:
Tue Jun 19 23:40:46 UTC 2012, org.apache.hadoop.hbase.client.HTable$3@571a4bd4,
java.io.IOException:
org.apache.hadoop.hbase.client.HConnectionManager$HConnectionImplementation@2eb0a3f5
closed
Tue Jun 19 23:40:47 UTC 2012, org.apache.hadoop.hbase.client.HTable$3@571a4bd4,
java.io.IOException:
org.apache.hadoop.hbase.client.HConnectionManager$HConnectionImplementation@2eb0a3f5
closed
Tue Jun 19 23:40:48 UTC 2012, org.apache.hadoop.hbase.client.HTable$3@571a4bd4,
java.io.IOException:
org.apache.hadoop.hbase.client.HConnectionManager$HConnectionImplementation@2eb0a3f5
closed
Tue Jun 19 23:40:49 UTC 2012, org.apache.hadoop.hbase.client.HTable$3@571a4bd4,
java.io.IOException:
org.apache.hadoop.hbase.client.HConnectionManager$HConnectionImplementation@2eb0a3f5
closed
Tue Jun 19 23:40:51 UTC 2012, org.apache.hadoop.hbase.client.HTable$3@571a4bd4,
java.io.IOException:
org.apache.hadoop.hbase.client.HConnectionManager$HConnectionImplementation@2eb0a3f5
closed
Tue Jun 19 23:40:53 UTC 2012, org.apache.hadoop.hbase.client.HTable$3@571a4bd4,
java.io.IOException:
org.apache.hadoop.hbase.client.HConnectionManager$HConnectionImplementation@2eb0a3f5
closed
Tue Jun 19 23:40:57 UTC 2012, org.apache.hadoop.hbase.client.HTable$3@571a4bd4,
java.io.IOException:
org.apache.hadoop.hbase.client.HConnectionManager$HConnectionImplementation@2eb0a3f5
closed
Tue Jun 19 23:41:01 UTC 2012, org.apache.hadoop.hbase.client.HTable$3@571a4bd4,
java.io.IOException:
org.apache.hadoop.hbase.client.HConnectionManager$HConnectionImplementation@2eb0a3f5
closed
Tue Jun 19 23:41:09 UTC 2012, org.apache.hadoop.hbase.client.HTable$3@571a4bd4,
java.io.IOException:
org.apache.hadoop.hbase.client.HConnectionManager$HConnectionImplementation@2eb0a3f5
closed
Tue Jun 19 23:41:25 UTC 2012, org.apache.hadoop.hbase.client.HTable$3@571a4bd4,
java.io.IOException:
org.apache.hadoop.hbase.client.HConnectionManager$HConnectionImplementation@2eb0a3f5
closed
{noformat}
This was caused by the little dance up in HBaseAdmin where it deletes "stale"
connections... which are not stale at all.
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