content: /*
   * 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.bookkeeper.tests.integration.utils;
  
  import java.util.concurrent.Callable;
  import java.util.concurrent.CompletableFuture;
  import java.util.concurrent.atomic.AtomicInteger;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * A thread reaper.
   */
  public class ThreadReaper {
      private static final Logger LOG = LoggerFactory.getLogger(ThreadReaper.class);
      private static AtomicInteger groupId = new AtomicInteger(0);
  
      public static <T> T runWithReaper(Callable<T> callable) throws Exception {
          ThreadGroup tg = new ThreadGroup("reaper-group-" + groupId.incrementAndGet());
          CompletableFuture<T> promise = new CompletableFuture<>();
          Thread t = new Thread(tg, () -> {
                  try {
                      promise.complete(callable.call());
                  } catch (Throwable ex) {
                      promise.completeExceptionally(ex);
                  }
          }, "reapable-thread");
          t.start();
          T ret = promise.get();
  
          int i = 30; // try to clean up for 3 seconds
          while (tg.activeCount() > 0 && i > 0) {
              tg.interrupt();
              Thread.sleep(100);
              LOG.info("{} threads still alive", tg.activeCount());
              i--;
          }
          if (tg.activeCount() == 0) {
              LOG.info("All threads in reaper group dead");
          } else {
              Thread[] threads = new Thread[tg.activeCount()];
              int found = tg.enumerate(threads);
              LOG.info("Leaked {} threads", found);
              for (int j = 0; j < found; j++) {
                  LOG.info("Leaked thread {}", threads[j]);
              }
          }
          return ret;
      }
  }
  