HADOOP-15239 S3ABlockOutputStream.flush() be no-op when stream closed. Contributed by Gabor Bota.

hadoop-tools/hadoop-aws/src/main/java/org/apache/hadoop/fs/s3a/S3ABlockOutputStream.java

@@ -238,7 +238,12 @@ void checkOpen() throws IOException {
    */
   @Override
   public synchronized void flush() throws IOException {
+    try {
       checkOpen();
+    } catch (IOException e) {
+      LOG.warn("Stream closed: " + e.getMessage());
+      return;
+    }
     S3ADataBlocks.DataBlock dataBlock = getActiveBlock();
     if (dataBlock != null) {
       dataBlock.flush();

hadoop-tools/hadoop-aws/src/test/java/org/apache/hadoop/fs/s3a/TestS3ABlockOutputStream.java

@@ -0,0 +1,66 @@
+/*
+ * 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.hadoop.fs.s3a;
+
+import org.apache.hadoop.fs.s3a.commit.PutTracker;
+import org.apache.hadoop.util.Progressable;
+import org.junit.Before;
+import org.junit.Test;
+
+import java.io.IOException;
+import java.util.concurrent.ExecutorService;
+
+import static org.junit.Assert.*;
+import static org.mockito.Mockito.doThrow;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.spy;
+
+/**
+ * Unit tests for {@link S3ABlockOutputStream}.
+ */
+public class TestS3ABlockOutputStream extends AbstractS3AMockTest {
+
+  private S3ABlockOutputStream stream;
+
+  @Before
+  public void setUp() throws Exception {
+    ExecutorService executorService = mock(ExecutorService.class);
+    Progressable progressable = mock(Progressable.class);
+    S3ADataBlocks.BlockFactory blockFactory =
+        mock(S3ADataBlocks.BlockFactory.class);
+    long blockSize = Constants.DEFAULT_MULTIPART_SIZE;
+    S3AInstrumentation.OutputStreamStatistics statistics = null;
+    WriteOperationHelper oHelper = mock(WriteOperationHelper.class);
+    PutTracker putTracker = mock(PutTracker.class);
+    stream = spy(new S3ABlockOutputStream(fs, "", executorService,
+      progressable, blockSize, blockFactory, statistics, oHelper,
+      putTracker));
+  }
+
+  @Test
+  public void testFlushNoOpWhenStreamClosed() throws Exception {
+    doThrow(new IOException()).when(stream).checkOpen();
+
+    try {
+      stream.flush();
+    } catch (Exception e){
+      fail("Should not have any exception.");
+    }
+  }
+}