| package org.apache.lucene.index; |
| |
| /* |
| * 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.util.IdentityHashMap; |
| import java.util.Map; |
| |
| import org.apache.lucene.index.DocumentsWriterPerThreadPool.ThreadState; |
| import org.apache.lucene.util.ThreadInterruptedException; |
| |
| /** |
| * Controls the health status of a {@link DocumentsWriter} sessions. This class |
| * used to block incoming indexing threads if flushing significantly slower than |
| * indexing to ensure the {@link DocumentsWriter}s healthiness. If flushing is |
| * significantly slower than indexing the net memory used within an |
| * {@link IndexWriter} session can increase very quickly and easily exceed the |
| * JVM's available memory. |
| * <p> |
| * To prevent OOM Errors and ensure IndexWriter's stability this class blocks |
| * incoming threads from indexing once 2 x number of available |
| * {@link ThreadState}s in {@link DocumentsWriterPerThreadPool} is exceeded. |
| * Once flushing catches up and the number of flushing DWPT is equal or lower |
| * than the number of active {@link ThreadState}s threads are released and can |
| * continue indexing. |
| */ |
| final class DocumentsWriterStallControl { |
| |
| private volatile boolean stalled; |
| private int numWaiting; // only with assert |
| private boolean wasStalled; // only with assert |
| private final Map<Thread, Boolean> waiting = new IdentityHashMap<>(); // only with assert |
| |
| /** |
| * Update the stalled flag status. This method will set the stalled flag to |
| * <code>true</code> iff the number of flushing |
| * {@link DocumentsWriterPerThread} is greater than the number of active |
| * {@link DocumentsWriterPerThread}. Otherwise it will reset the |
| * {@link DocumentsWriterStallControl} to healthy and release all threads |
| * waiting on {@link #waitIfStalled()} |
| */ |
| synchronized void updateStalled(boolean stalled) { |
| this.stalled = stalled; |
| if (stalled) { |
| wasStalled = true; |
| } |
| notifyAll(); |
| } |
| |
| /** |
| * Blocks if documents writing is currently in a stalled state. |
| * |
| */ |
| void waitIfStalled() { |
| if (stalled) { |
| synchronized (this) { |
| if (stalled) { // react on the first wakeup call! |
| // don't loop here, higher level logic will re-stall! |
| try { |
| assert incWaiters(); |
| wait(); |
| assert decrWaiters(); |
| } catch (InterruptedException e) { |
| throw new ThreadInterruptedException(e); |
| } |
| } |
| } |
| } |
| } |
| |
| boolean anyStalledThreads() { |
| return stalled; |
| } |
| |
| |
| private boolean incWaiters() { |
| numWaiting++; |
| assert waiting.put(Thread.currentThread(), Boolean.TRUE) == null; |
| |
| return numWaiting > 0; |
| } |
| |
| private boolean decrWaiters() { |
| numWaiting--; |
| assert waiting.remove(Thread.currentThread()) != null; |
| return numWaiting >= 0; |
| } |
| |
| synchronized boolean hasBlocked() { // for tests |
| return numWaiting > 0; |
| } |
| |
| boolean isHealthy() { // for tests |
| return !stalled; // volatile read! |
| } |
| |
| synchronized boolean isThreadQueued(Thread t) { // for tests |
| return waiting.containsKey(t); |
| } |
| |
| synchronized boolean wasStalled() { // for tests |
| return wasStalled; |
| } |
| } |