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Lucene example source code file (CloseableThreadLocal.java)
The Lucene CloseableThreadLocal.java source codepackage org.apache.lucene.util; /** * 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. */ import java.io.Closeable; import java.lang.ref.WeakReference; import java.util.HashMap; import java.util.Iterator; import java.util.Map; /** Java's builtin ThreadLocal has a serious flaw: * it can take an arbitrarily long amount of time to * dereference the things you had stored in it, even once the * ThreadLocal instance itself is no longer referenced. * This is because there is single, master map stored for * each thread, which all ThreadLocals share, and that * master map only periodically purges "stale" entries. * * While not technically a memory leak, because eventually * the memory will be reclaimed, it can take a long time * and you can easily hit OutOfMemoryError because from the * GC's standpoint the stale entries are not reclaimable. * * This class works around that, by only enrolling * WeakReference values into the ThreadLocal, and * separately holding a hard reference to each stored * value. When you call {@link #close}, these hard * references are cleared and then GC is freely able to * reclaim space by objects stored in it. * * We can not rely on {@link ThreadLocal#remove()} as it * only removes the value for the caller thread, whereas * {@link #close} takes care of all * threads. You should not call {@link #close} until all * threads are done using the instance. * * @lucene.internal */ public class CloseableThreadLocal<T> implements Closeable { private ThreadLocal<WeakReference Other Lucene examples (source code examples)Here is a short list of links related to this Lucene CloseableThreadLocal.java source code file: |
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