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.beam.sdk.options;
  
  import com.fasterxml.jackson.annotation.JsonIgnore;
  import java.util.concurrent.ScheduledExecutorService;
  import org.apache.beam.sdk.util.UnboundedScheduledExecutorService;
  
  /**
   * Options for configuring the {@link ScheduledExecutorService} used throughout the Java runtime.
   */
  public interface ExecutorOptions extends PipelineOptions {
  
    /**
     * The {@link ScheduledExecutorService} instance to use to create threads, can be overridden to
     * specify a {@link ScheduledExecutorService} that is compatible with the user's environment. If
     * unset, the default is to create an {@link UnboundedScheduledExecutorService}.
     */
    @JsonIgnore
    @Description(
        "The ScheduledExecutorService instance to use to create threads, can be overridden to specify "
            + "a ScheduledExecutorService that is compatible with the user's environment. If unset, "
            + "the default is to create an UnboundedScheduledExecutorService.")
    @Default.InstanceFactory(ScheduledExecutorServiceFactory.class)
    @Hidden
    ScheduledExecutorService getScheduledExecutorService();
  
    void setScheduledExecutorService(ScheduledExecutorService value);
  
    /** Returns the default {@link ScheduledExecutorService} to use within the Apache Beam SDK. */
    class ScheduledExecutorServiceFactory implements DefaultValueFactory<ScheduledExecutorService> {
      @Override
      public ScheduledExecutorService create(PipelineOptions options) {
        /* The SDK requires an unbounded thread pool because a step may create X writers
         * each requiring their own thread to perform the writes otherwise a writer may
         * block causing deadlock for the step because the writers buffer is full.
         * Also, the MapTaskExecutor launches the steps in reverse order and completes
         * them in forward order thus requiring enough threads so that each step's writers
         * can be active.
         */
        return new UnboundedScheduledExecutorService();
      }
    }
  }
  