Github user NicoK commented on a diff in the pull request: https://github.com/apache/flink/pull/4581#discussion_r152944166 --- Diff: flink-runtime/src/test/java/org/apache/flink/runtime/io/network/partition/SpillableSubpartitionTest.java --- @@ -320,4 +559,40 @@ void awaitNotifications(long awaitedNumNotifiedBuffers, long timeoutMillis) thro } } } + + /** + * An {@link IOManagerAsync} that creates closed {@link BufferFileWriter} instances in its + * {@link #createBufferFileWriter(FileIOChannel.ID)} method. + * + * <p>These {@link BufferFileWriter} objects will thus throw an exception when trying to add + * write requests, e.g. by calling {@link BufferFileWriter#writeBlock(Object)}. + */ + private static class IOManagerAsyncWithClosedBufferFileWriter extends IOManagerAsync { + @Override + public BufferFileWriter createBufferFileWriter(FileIOChannel.ID channelID) + throws IOException { + BufferFileWriter bufferFileWriter = super.createBufferFileWriter(channelID); + bufferFileWriter.close(); + return bufferFileWriter; + } + } + + /** + * An {@link IOManagerAsync} that creates stalling {@link BufferFileWriter} instances in its + * {@link #createBufferFileWriter(FileIOChannel.ID)} method. + * + * <p>These {@link BufferFileWriter} objects will accept {@link BufferFileWriter#writeBlock(Object)} + * requests but never actually perform any write operation (be sure to clean up the buffers + * manually!). + */ + private static class IOManagerAsyncWithStallingBufferFileWriter extends IOManagerAsync { + @Override + public BufferFileWriter createBufferFileWriter(FileIOChannel.ID channelID) + throws IOException { + BufferFileWriter bufferFileWriter = spy(super.createBufferFileWriter(channelID)); --- End diff -- I don't have (too) hard feelings about it, so there it is - along with some more minor fixes in the tests and one additional test for `AsynchronousBufferFileWriter` itself (the change there was not covered yet)
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