org.apache.hive.service.server.ThreadFactoryWithGarbageCleanup Maven / Gradle / Ivy
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* to you under the Apache License, Version 2.0 (the
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* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
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*/
package org.apache.hive.service.server;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ThreadFactory;
import org.apache.hadoop.hive.metastore.RawStore;
/**
* A ThreadFactory for constructing new HiveServer2 threads that lets you plug
* in custom cleanup code to be called before this thread is GC-ed.
* Currently cleans up the following:
* 1. ThreadLocal RawStore object:
* In case of an embedded metastore, HiveServer2 threads (foreground & background)
* end up caching a ThreadLocal RawStore object. The ThreadLocal RawStore object has
* an instance of PersistenceManagerFactory & PersistenceManager.
* The PersistenceManagerFactory keeps a cache of PersistenceManager objects,
* which are only removed when PersistenceManager#close method is called.
* HiveServer2 uses ExecutorService for managing thread pools for foreground & background threads.
* ExecutorService unfortunately does not provide any hooks to be called,
* when a thread from the pool is terminated.
* As a solution, we're using this ThreadFactory to keep a cache of RawStore objects per thread.
* And we are doing clean shutdown in the finalizer for each thread.
*/
public class ThreadFactoryWithGarbageCleanup implements ThreadFactory {
private static Map threadRawStoreMap = new ConcurrentHashMap();
private final String namePrefix;
public ThreadFactoryWithGarbageCleanup(String threadPoolName) {
namePrefix = threadPoolName;
}
@Override
public Thread newThread(Runnable runnable) {
Thread newThread = new ThreadWithGarbageCleanup(runnable);
newThread.setName(namePrefix + ": Thread-" + newThread.getId());
return newThread;
}
public static Map getThreadRawStoreMap() {
return threadRawStoreMap;
}
}