[HBASE-2966] HBase client stuck on org.apache.zookeeper.ClientCnxn.submitRequest(ClientCnxn.java:1278) holding regionLockObject lock

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Cannot Reproduce
• Assignee: Unassigned
• Reporter: Kannan Muthukkaruppan
• Created: 08/Sep/10 05:46
• Updated: 12/Jun/22 00:10
• Resolved: 16/Jul/14 23:03

Description

We noticed in one case the HBase client program got stuck on Zookeeper.exists() call.

One of the threads was stuck here on the ZK call while holding an HBase level lock (regionLockObject in locateRegionInMeta()).

 
"thrift-0-thread-8" prio=10 tid=0x00007f189ca4c000 nid=0x550f in Object.wait() [0x0000000044241000]
   java.lang.Thread.State: WAITING (on object monitor)
                at java.lang.Object.wait(Native Method)
                at java.lang.Object.wait(Object.java:485)
                at org.apache.zookeeper.ClientCnxn.submitRequest(ClientCnxn.java:1278)
                - locked <0x00007f1903a0c280> (a org.apache.zookeeper.ClientCnxn$Packet)
                at org.apache.zookeeper.ZooKeeper.exists(ZooKeeper.java:804)
                at org.apache.zookeeper.ZooKeeper.exists(ZooKeeper.java:837)
                at org.apache.hadoop.hbase.zookeeper.ZooKeeperWrapper.getRSDirectoryCount(ZooKeeperWrapper.java:765)
                at org.apache.hadoop.hbase.client.HTable.getCurrentNrHRS(HTable.java:173)
                at org.apache.hadoop.hbase.client.HTable.<init>(HTable.java:147)
                at org.apache.hadoop.hbase.client.MetaScanner.metaScan(MetaScanner.java:124)
                at org.apache.hadoop.hbase.client.MetaScanner.metaScan(MetaScanner.java:89)
                at org.apache.hadoop.hbase.client.HConnectionManager$TableServers.prefetchRegionCache(HConnectionManager.java:734)
                at org.apache.hadoop.hbase.client.HConnectionManager$TableServers.locateRegionInMeta(HConnectionManager.java:785)
                - locked <0x00007f190d868848> (a java.lang.Object)
                at org.apache.hadoop.hbase.client.HConnectionManager$TableServers.locateRegion(HConnectionManager.java:679)
                at org.apache.hadoop.hbase.client.HConnectionManager$TableServers.locateRegion(HConnectionManager.java:646)
                at org.apache.hadoop.hbase.client.HConnectionManager$TableServers.getRegionLocation(HConnectionManager.java:472)
                at org.apache.hadoop.hbase.client.ServerCallable.instantiateServer(ServerCallable.java:57)
                at org.apache.hadoop.hbase.client.HConnectionManager$TableServers.getRegionServerWithRetries(HConnectionManager.java:1147)
                at org.apache.hadoop.hbase.client.HTable.get(HTable.java:503)

The remaining other threads are all waiting on the regionLockObject lock (held by the above thread) with stacks like:

thrift-0-thread-7" prio=10 tid=0x00007f189ca4a800 nid=0x550e waiting for monitor entry [0x0000000044141000]
   java.lang.Thread.State: BLOCKED (on object monitor)
                at org.apache.hadoop.hbase.client.HConnectionManager$TableServers.locateRegionInMeta(HConnectionManager.java:783)
                - waiting to lock <0x00007f190d868848> (a java.lang.Object)
                at org.apache.hadoop.hbase.client.HConnectionManager$TableServers.locateRegion(HConnectionManager.java:679)
                at org.apache.hadoop.hbase.client.HConnectionManager$TableServers.locateRegion(HConnectionManager.java:646)
                at org.apache.hadoop.hbase.client.HConnectionManager$TableServers.getRegionLocation(HConnectionManager.java:472)
                at org.apache.hadoop.hbase.client.ServerCallable.instantiateServer(ServerCallable.java:57)
                at org.apache.hadoop.hbase.client.HConnectionManager$TableServers.getRegionServerWithRetries(HConnectionManager.java:1147)
                at org.apache.hadoop.hbase.client.HTable.get(HTable.java:503)

Any ideas?

Meanwhile, I'll look into the ZK logs from the relevant time some more and get back if I have more information.

Issue Links

• relates to: ZOOKEEPER-846 zookeeper client doesn't shut down cleanly on the close call