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Posted to commits@hbase.apache.org by en...@apache.org on 2014/06/28 02:31:21 UTC
[35/49] git commit: HBASE-10785 Metas own location should be cached
HBASE-10785 Metas own location should be cached
git-svn-id: https://svn.apache.org/repos/asf/hbase/branches/hbase-10070@1586653 13f79535-47bb-0310-9956-ffa450edef68
Project: http://git-wip-us.apache.org/repos/asf/hbase/repo
Commit: http://git-wip-us.apache.org/repos/asf/hbase/commit/48ffa4d5
Tree: http://git-wip-us.apache.org/repos/asf/hbase/tree/48ffa4d5
Diff: http://git-wip-us.apache.org/repos/asf/hbase/diff/48ffa4d5
Branch: refs/heads/master
Commit: 48ffa4d5e615c78f6db8f6c2beddd93460887642
Parents: 579f305
Author: Enis Soztutar <en...@apache.org>
Authored: Fri Apr 11 13:46:59 2014 +0000
Committer: Enis Soztutar <en...@apache.org>
Committed: Fri Jun 27 16:39:39 2014 -0700
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.../hadoop/hbase/client/ConnectionManager.java | 36 +++++++++++++++++++-
1 file changed, 35 insertions(+), 1 deletion(-)
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http://git-wip-us.apache.org/repos/asf/hbase/blob/48ffa4d5/hbase-client/src/main/java/org/apache/hadoop/hbase/client/ConnectionManager.java
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diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/ConnectionManager.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/ConnectionManager.java
index ff30ef4..d6d6491 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/ConnectionManager.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/ConnectionManager.java
@@ -560,6 +560,9 @@ class ConnectionManager {
// package protected for the tests
ClusterStatusListener clusterStatusListener;
+
+ private final Object metaRegionLock = new Object();
+
// We have a single lock for master & zk to prevent deadlocks. Having
// one lock for ZK and one lock for master is not possible:
// When creating a connection to master, we need a connection to ZK to get
@@ -1085,13 +1088,44 @@ 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, row, useCache, retry, replicaId);
}
}
+ 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 the hbase:meta table for the HRegionLocation
* info that contains the table and row we're seeking.