Github user saintstack commented on a diff in the pull request:
https://github.com/apache/spark/pull/1608#discussion_r16608329
--- Diff:
external/hbase/src/main/scala/org/apache/spark/hbase/HConnectionStaticCache.scala
---
@@ -0,0 +1,149 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.spark.hbase
+
+import org.apache.hadoop.hbase.client.HConnection
+import java.util.concurrent.atomic.AtomicInteger
+import java.util.concurrent.atomic.AtomicLong
+import java.util.Timer
+import org.apache.hadoop.conf.Configuration
+import org.apache.hadoop.hbase.HConstants
+import org.apache.hadoop.hbase.client.HConnectionManager
+import java.util.TimerTask
+import scala.collection.mutable.MutableList
+import org.apache.spark.Logging
+import scala.collection.mutable.SynchronizedMap
+import scala.collection.mutable.HashMap
+
+/**
+ * A static caching class that will manage all HConnection in a worker
+ *
+ * The main idea is there is a hashMap with
+ * HConstants.HBASE_CLIENT_INSTANCE_ID which is
("hbase.client.instance.id")
+ *
+ * In that HashMap there is three things
+ * - HConnection
+ * - Number of checked out users of the HConnection
+ * - Time since the HConnection was last used
+ *
+ * There is also a Timer thread that will start up every 2 minutes
+ * When the Timer thread starts up it will look for HConnection with no
+ * checked out users and a last used time that is older then 1 minute.
+ *
+ * This class is not intended to be used by Users
+ */
+object HConnectionStaticCache extends Logging {
+ @transient private val hconnectionMap =
+ new HashMap[String, (HConnection, AtomicInteger, AtomicLong)] with
SynchronizedMap[String, (HConnection, AtomicInteger, AtomicLong)]
+
+ @transient private val hconnectionTimeout = 60000
+
+ @transient private val hconnectionCleaner = new Timer
+
+ hconnectionCleaner.schedule(new hconnectionCleanerTask,
hconnectionTimeout * 2)
+
+ /**
+ * Gets or starts a HConnection based on a config object
+ */
+ def getHConnection(config: Configuration): HConnection = {
+ val instanceId = config.get(HConstants.HBASE_CLIENT_INSTANCE_ID)
+ var hconnectionAndCounter =
hconnectionMap.get(instanceId).getOrElse(null)
+ if (hconnectionAndCounter == null) {
+ hconnectionMap.synchronized {
+ hconnectionAndCounter =
hconnectionMap.get(instanceId).getOrElse(null)
+ if (hconnectionAndCounter == null) {
+
+ val hConnection = HConnectionManager.createConnection(config)
+ hconnectionAndCounter = (hConnection, new AtomicInteger, new
AtomicLong)
+ hconnectionMap.put(instanceId, hconnectionAndCounter)
+
+ }
+ }
+ logDebug("Created hConnection '" + instanceId + "'");
+ } else {
+ logDebug("Get hConnection from cache '" + instanceId + "'");
+ }
+ hconnectionAndCounter._2.incrementAndGet()
+ return hconnectionAndCounter._1
+ }
+
+ /**
+ * tell us a thread is no longer using a HConnection
+ */
+ def finishWithHConnection(config: Configuration, hconnection:
HConnection) {
+ val instanceId = config.get(HConstants.HBASE_CLIENT_INSTANCE_ID)
+
+ var hconnectionAndCounter =
hconnectionMap.get(instanceId).getOrElse(null)
+ if (hconnectionAndCounter != null) {
+ var usesLeft = hconnectionAndCounter._2.decrementAndGet()
+ if (usesLeft < 0) {
+ hconnectionAndCounter._2.set(0)
+ usesLeft = 0
+ }
+ if (usesLeft == 0) {
+ hconnectionAndCounter._3.set(System.currentTimeMillis())
+ logDebug("Finished last use of hconnection '" + instanceId + "'");
+ } else {
+ logDebug("Finished a use of hconnection '" + instanceId + "' with
" + usesLeft + " uses left");
+ }
+ } else {
+ logWarning("Tried to remove use of '" + instanceId + "' but nothing
was there");
+ }
+ }
+
+ /**
+ * The timer thread that cleans up the HashMap of Collections
+ */
+ protected class hconnectionCleanerTask extends TimerTask {
+ override def run() {
+
+ logDebug("Running hconnectionCleanerTask:" + hconnectionMap.size);
+
+ val removeList = new MutableList[String]
+
+ hconnectionMap.foreach(entry => {
+ if (entry._1 == 0 &&
+ entry._2._3.get() + 60000 < System.currentTimeMillis()) {
+ removeList.+=(entry._1)
+ }
+ })
+
+ if (removeList.length > 0) {
+ hconnectionMap.synchronized {
+ removeList.foreach(key => {
+ val v = hconnectionMap.get(key).getOrElse(null)
+ if (v != null) {
+ if (v._2.get() == 0 &&
+ v._3.get() + 60000 < System.currentTimeMillis()) {
+
+ logDebug("closing hconnection: " + key);
+
+ v._1.close()
+
+ hconnectionMap.remove(key);
+ }
+ } else {
+ logWarning("Tried to remove use of '" + key + "' but nothing
was there");
+ }
+ })
+ }
+ }
+ }
+ }
+
+}
--- End diff --
You don't seem to have unit test for this class. Suggest you add one to
ensure basic ref counting doing its job.
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