[HBASE-9322] Contention on the SoftValueSortedMap with multiple clients

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Won't Fix
• Affects Version/s: 0.95.2
• Fix Version/s: 0.98.0, 0.96.1
• Assignee: Unassigned
• Reporter: Jean-Daniel Cryans
• Created: 23/Aug/13 18:10
• Updated: 16/Dec/13 18:46
• Resolved: 23/Nov/13 20:06

Description

I've been running tests on clusters with "lots" of regions, about 400, and I'm seeing weird contention in the client.

This one shows up a lot around the SoftValueSortedMap.

First I have this blocked thread on I'm not sure what:

"TestClient-12" prio=10 tid=0x00007fb268872000 nid=0x3add waiting for monitor entry [0x00007fb251416000]
   java.lang.Thread.State: BLOCKED (on object monitor)
	at org.apache.hadoop.hbase.util.SoftValueSortedMap.isEmpty(SoftValueSortedMap.java:210)
	- locked <0x00000000c1b70318> (a java.util.TreeMap)
	at org.apache.hadoop.hbase.client.HConnectionManager$HConnectionImplementation.getCachedLocation(HConnectionManager.java:1263)
	at org.apache.hadoop.hbase.client.HConnectionManager$HConnectionImplementation.locateRegionInMeta(HConnectionManager.java:1103)
	at org.apache.hadoop.hbase.client.HConnectionManager$HConnectionImplementation.locateRegion(HConnectionManager.java:1036)
	at org.apache.hadoop.hbase.client.HConnectionManager$HConnectionImplementation.locateRegion(HConnectionManager.java:993)

This client waits on it:

"TestClient-14" prio=10 tid=0x00007fb268876000 nid=0x3adf waiting for monitor entry [0x00007fb251214000]
   java.lang.Thread.State: BLOCKED (on object monitor)
	at org.apache.hadoop.hbase.util.SoftValueSortedMap.lowerValueByKey(SoftValueSortedMap.java:189)
	- waiting to lock <0x00000000c1b70318> (a java.util.TreeMap)
	- locked <0x00000000c1b82120> (a org.apache.hadoop.hbase.util.SoftValueSortedMap)
	at org.apache.hadoop.hbase.client.HConnectionManager$HConnectionImplementation.getCachedLocation(HConnectionManager.java:1272)
	at org.apache.hadoop.hbase.client.HConnectionManager$HConnectionImplementation.locateRegionInMeta(HConnectionManager.java:1103)
	at org.apache.hadoop.hbase.client.HConnectionManager$HConnectionImplementation.locateRegion(HConnectionManager.java:1036)
	at org.apache.hadoop.hbase.client.HConnectionManager$HConnectionImplementation.locateRegion(HConnectionManager.java:993)

As you can see it's also holding a lock, which I have 11 other clients waiting on:

"TestClient-13" prio=10 tid=0x00007fb268874000 nid=0x3ade waiting for monitor entry [0x00007fb251315000]
   java.lang.Thread.State: BLOCKED (on object monitor)
	at org.apache.hadoop.hbase.util.SoftValueSortedMap.lowerValueByKey(SoftValueSortedMap.java:189)
	- waiting to lock <0x00000000c1b82120> (a org.apache.hadoop.hbase.util.SoftValueSortedMap)
	at org.apache.hadoop.hbase.client.HConnectionManager$HConnectionImplementation.getCachedLocation(HConnectionManager.java:1272)
	at org.apache.hadoop.hbase.client.HConnectionManager$HConnectionImplementation.locateRegionInMeta(HConnectionManager.java:1103)
	at org.apache.hadoop.hbase.client.HConnectionManager$HConnectionImplementation.locateRegion(HConnectionManager.java:1036)
	at org.apache.hadoop.hbase.client.HConnectionManager$HConnectionImplementation.locateRegion(HConnectionManager.java:993)