001/*
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *     http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018package org.apache.hadoop.hbase.util;
019
020import static org.junit.jupiter.api.Assertions.assertEquals;
021import static org.junit.jupiter.api.Assertions.fail;
022
023import java.util.ArrayList;
024import java.util.HashMap;
025import java.util.List;
026import java.util.Map;
027import java.util.concurrent.ThreadLocalRandom;
028import java.util.concurrent.atomic.AtomicBoolean;
029import org.apache.hadoop.hbase.testclassification.SmallTests;
030import org.junit.jupiter.api.Tag;
031import org.junit.jupiter.api.Test;
032import org.slf4j.Logger;
033import org.slf4j.LoggerFactory;
034
035@Tag(SmallTests.TAG)
036public class TestFastStringPool {
037
038  private static final Logger LOG = LoggerFactory.getLogger(TestFastStringPool.class);
039
040  @Test
041  public void testMultiThread() throws InterruptedException {
042    FastStringPool pool = new FastStringPool();
043    List<String> list1 = new ArrayList<>();
044    List<String> list2 = new ArrayList<>();
045    for (int i = 0; i < 1000; i++) {
046      list1.add("list1-" + i);
047      list2.add("list2-" + i);
048    }
049    Map<String, String> interned1 = new HashMap<>();
050    Map<String, String> interned2 = new HashMap<>();
051    AtomicBoolean failed = new AtomicBoolean(false);
052    int numThreads = 10;
053    List<Thread> threads = new ArrayList<>();
054    for (int i = 0; i < numThreads; i++) {
055      threads.add(new Thread(() -> {
056        ThreadLocalRandom rand = ThreadLocalRandom.current();
057        for (int j = 0; j < 1000000; j++) {
058          List<String> list;
059          Map<String, String> interned;
060          if (rand.nextBoolean()) {
061            list = list1;
062            interned = interned1;
063          } else {
064            list = list2;
065            interned = interned2;
066          }
067          // create a new reference
068          String k = new String(list.get(rand.nextInt(list.size())));
069          String v = pool.intern(k);
070          synchronized (interned) {
071            String prev = interned.get(k);
072            if (prev != null) {
073              // should always return the same reference
074              if (prev != v) {
075                failed.set(true);
076                String msg = "reference not equal, intern failed on string " + k;
077                LOG.error(msg);
078                throw new AssertionError(msg);
079              }
080            } else {
081              interned.put(k, v);
082            }
083          }
084        }
085      }));
086    }
087    for (Thread t : threads) {
088      t.start();
089    }
090    for (Thread t : threads) {
091      t.join();
092    }
093    LOG.info("interned1 size {}, interned2 size {}, pool size {}", interned1.size(),
094      interned2.size(), pool.size());
095    assertEquals(interned1.size() + interned2.size(), pool.size());
096    interned1.clear();
097    list1.clear();
098    LOG.info("clear interned1");
099    // wait for at most 30 times
100    for (int i = 0; i < 30; i++) {
101      // invoke gc manually
102      LOG.info("trigger GC");
103      System.gc();
104      Thread.sleep(1000);
105      // should have cleaned up all the references for list1
106      if (interned2.size() == pool.size()) {
107        return;
108      }
109    }
110    fail("should only have list2 strings in pool, expected pool size " + interned2.size()
111      + ", but got " + pool.size());
112  }
113}