Author: enis
Date: Fri Apr 11 13:46:59 2014
New Revision: 1586653
URL: http://svn.apache.org/r1586653
Log:
HBASE-10785 Metas own location should be cached
Modified:
hbase/branches/hbase-10070/hbase-client/src/main/java/org/apache/hadoop/hbase/client/ConnectionManager.java
Modified:
hbase/branches/hbase-10070/hbase-client/src/main/java/org/apache/hadoop/hbase/client/ConnectionManager.java
URL:
http://svn.apache.org/viewvc/hbase/branches/hbase-10070/hbase-client/src/main/java/org/apache/hadoop/hbase/client/ConnectionManager.java?rev=1586653&r1=1586652&r2=1586653&view=diff
==============================================================================
---
hbase/branches/hbase-10070/hbase-client/src/main/java/org/apache/hadoop/hbase/client/ConnectionManager.java
(original)
+++
hbase/branches/hbase-10070/hbase-client/src/main/java/org/apache/hadoop/hbase/client/ConnectionManager.java
Fri Apr 11 13:46:59 2014
@@ -592,6 +592,8 @@ class ConnectionManager {
// package protected for the tests
ClusterStatusListener clusterStatusListener;
+ private final Object metaRegionLock = new Object();
+
private final Object userRegionLock = new Object();
// We have a single lock for master & zk to prevent deadlocks. Having
@@ -1117,7 +1119,7 @@ class ConnectionManager {
}
if (tableName.equals(TableName.META_TABLE_NAME)) {
- return this.registry.getMetaRegionLocation();
+ return locateMeta(tableName, useCache, replicaId);
} else {
// Region not in the cache - have to go to the meta RS
return locateRegionInMeta(TableName.META_TABLE_NAME, tableName, row,
@@ -1125,6 +1127,37 @@ class ConnectionManager {
}
}
+ private RegionLocations locateMeta(final TableName tableName,
+ boolean useCache, int replicaId) throws IOException {
+ // HBASE-10785: We cache the location of the META itself, so that we are
not overloading
+ // zookeeper with one request for every region lookup. We cache the META
with empty row
+ // key in MetaCache.
+ byte[] metaCacheKey = HConstants.EMPTY_START_ROW; // use byte[0] as the
row for meta
+ RegionLocations locations = null;
+ if (useCache) {
+ locations = getCachedLocation(tableName, metaCacheKey);
+ if (locations != null) {
+ return locations;
+ }
+ }
+
+ // only one thread should do the lookup.
+ synchronized (metaRegionLock) {
+ // Check the cache again for a hit in case some other thread made the
+ // same query while we were waiting on the lock.
+ locations = getCachedLocation(tableName, metaCacheKey);
+ if (locations != null) {
+ return locations;
+ }
+ // Look up from zookeeper
+ locations = this.registry.getMetaRegionLocation();
+ if (locations != null) {
+ cacheLocation(tableName, locations);
+ }
+ }
+ return locations;
+ }
+
/*
* Search hbase:meta for the HRegionLocation info that contains the table
and
* row we're seeking. It will prefetch certain number of regions info and
@@ -1211,7 +1244,7 @@ class ConnectionManager {
HRegionLocation metaLocation = null;
try {
// locate the meta region
- RegionLocations metaLocations = locateRegion(parentTable, metaKey,
true, false);
+ RegionLocations metaLocations = locateRegion(parentTable, metaKey,
tries == 0, false);
metaLocation = metaLocations == null ? null :
metaLocations.getDefaultRegionLocation();
// If null still, go around again.
if (metaLocation == null) continue;
