[HBASE-10785] Metas own location should be cached

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 0.99.0, hbase-10070
• Hadoop Flags: Reviewed
• Assignee: Enis Soztutar
• Reporter: Enis Soztutar
• Created: 18/Mar/14 21:33
• Updated: 25/Aug/15 23:21
• Resolved: 11/Apr/14 13:48

Description

With ROOT table gone, we no longer cache the location of the meta table (in MetaCache) in 96+. I've checked 94 code, and there we cache meta, but not root.

However, not caching the metas own location means that we are doing a zookeeper request every time we want to look up a regions location from meta. This means that there is a significant spike in zk requests whenever a region server goes down.

This affects trunk,0.98 and 0.96 as well as hbase-10070 branch. I've discovered the issue in hbase-10070 because of the integration test (HBASE-10572) results in 150K requests to zk in 10min.

A thread dump from one of the runs have 100+ threads from client in this stack trace:

	"TimeBoundedMultiThreadedReaderThread_20" prio=10 tid=0x00007f852c2f2000 nid=0x57b6 in Object.wait() [0x00007f85059e7000]
	   java.lang.Thread.State: WAITING (on object monitor)
		at java.lang.Object.wait(Native Method)
		at java.lang.Object.wait(Object.java:503)
		at org.apache.zookeeper.ClientCnxn.submitRequest(ClientCnxn.java:1309)
		- locked <0x00000000ea71aa78> (a org.apache.zookeeper.ClientCnxn$Packet)
		at org.apache.zookeeper.ZooKeeper.getData(ZooKeeper.java:1149)
		at org.apache.hadoop.hbase.zookeeper.RecoverableZooKeeper.getData(RecoverableZooKeeper.java:337)
		at org.apache.hadoop.hbase.zookeeper.ZKUtil.getData(ZKUtil.java:684)
		at org.apache.hadoop.hbase.zookeeper.ZKUtil.blockUntilAvailable(ZKUtil.java:1853)
		at org.apache.hadoop.hbase.zookeeper.MetaRegionTracker.blockUntilAvailable(MetaRegionTracker.java:186)
		at org.apache.hadoop.hbase.client.ZooKeeperRegistry.getMetaRegionLocation(ZooKeeperRegistry.java:60)
		at org.apache.hadoop.hbase.client.ConnectionManager$HConnectionImplementation.locateRegion(ConnectionManager.java:1126)
		at org.apache.hadoop.hbase.client.ConnectionManager$HConnectionImplementation.locateRegion(ConnectionManager.java:1112)
		at org.apache.hadoop.hbase.client.ConnectionManager$HConnectionImplementation.locateRegionInMeta(ConnectionManager.java:1220)
		at org.apache.hadoop.hbase.client.ConnectionManager$HConnectionImplementation.locateRegion(ConnectionManager.java:1129)
		at org.apache.hadoop.hbase.client.RpcRetryingCallerWithReadReplicas.getRegionLocations(RpcRetryingCallerWithReadReplicas.java:321)
		at org.apache.hadoop.hbase.client.RpcRetryingCallerWithReadReplicas.call(RpcRetryingCallerWithReadReplicas.java:257)
		- locked <0x00000000e9bcf238> (a org.apache.hadoop.hbase.client.RpcRetryingCallerWithReadReplicas)
		at org.apache.hadoop.hbase.client.HTable.get(HTable.java:818)
		at org.apache.hadoop.hbase.util.MultiThreadedReader$HBaseReaderThread.queryKey(MultiThreadedReader.java:288)
		at org.apache.hadoop.hbase.util.MultiThreadedReader$HBaseReaderThread.readKey(MultiThreadedReader.java:249)
		at org.apache.hadoop.hbase.util.MultiThreadedReader$HBaseReaderThread.runReader(MultiThreadedReader.java:192)
		at org.apache.hadoop.hbase.util.MultiThreadedReader$HBaseReaderThread.run(MultiThreadedReader.java:150)
	

Issue Links

• is duplicated by: HBASE-11758 Meta region location should be cached
• is related to: HBASE-10701 Cache invalidation improvements from client side
• is related to: HBASE-10070 HBase read high-availability using timeline-consistent region replicas