Github user chinmaykolhatkar commented on a diff in the pull request:
https://github.com/apache/incubator-apex-malhar/pull/157#discussion_r49928222
--- Diff:
library/src/main/java/com/datatorrent/lib/async/AbstractAsyncProcessor.java ---
@@ -0,0 +1,344 @@
+/**
+ * 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 com.datatorrent.lib.async;
+
+import java.util.Iterator;
+import java.util.Queue;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.Future;
+import javax.validation.constraints.Min;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import com.google.common.collect.Lists;
+
+import com.datatorrent.api.Context;
+import com.datatorrent.api.Operator.IdleTimeHandler;
+import com.datatorrent.common.util.BaseOperator;
+
+
+/**
+ * This base operator can be used to enqueue tuples for asynchronous and
parallel processing by separate worker threads.
+ *
+ * User can configure number of threads required for async processing. By
default
+ * threads will be created on need basis with no upper limit. These worker
threads, spawned by operator thread,
+ * can also be configured to processing timeout.
+ *
+ * <b>Workflow is as follows:</b>
+ * <ol>
+ * <li>Implementing class can enqueue the tuples of type QUEUETUPLE
using <i>enqueueTupleForProcessing</i>
+ * method.</li>
+ * <li>When a tuple gets its turn for execution,
<i>processTupleAsync</i> gets called
+ * by worker thread. This is asynchronous call</li>
+ * <li>Based on maintainTupleOrder parameter, the results are
consolidated at the end of every window and respective
+ * call to <i>handleProcessedTuple</i> will be made. This callback
is in operator thread.</li>
+ * </ol>
+ *
+ *
+ * <b>Use case examples:</b>
+ * <ul>
+ * <li>Parallel reads from external datastore/database system.</li>
+ * <li>Operations which are long running tasks per tuple but DAG i/o
should not be blocked.</li>
+ * </ul>
+ *
+ * @param <QUEUETUPLE> input type of tuple
+ * @param <RESULTTUPLE> Result of async processing of tuple.
+ */
+public abstract class AbstractAsyncProcessor<QUEUETUPLE, RESULTTUPLE>
extends BaseOperator implements IdleTimeHandler
+{
+ private static final Logger logger =
LoggerFactory.getLogger(AbstractAsyncProcessor.class);
+
+ /**
+ * This is an executor service which holds thread pool and enqueues task
for processing.
+ */
+ private transient ExecutorService executor;
+
+ /**
+ * Number of worker threads for processing
+ * 0 - Threads will be created as per need.
--- End diff --
I agree.What would you suggest a good ma number will be. I'll remove the
cached pool all together.
And put a limit on that.
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