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  1. Hadoop Map/Reduce
  2. MAPREDUCE-7076

TestNNBench#testNNBenchCreateReadAndDelete failing in our internal build

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    Details

    • Type: Bug
    • Status: Resolved
    • Priority: Minor
    • Resolution: Fixed
    • Affects Version/s: 2.8.0
    • Fix Version/s: 2.10.0, 3.3.0, 3.2.1, 3.1.3
    • Component/s: test
    • Labels:
    • Hadoop Flags:
      Reviewed

      Description

      TestNNBench#testNNBenchCreateReadAndDelete failed couple of times in our internal jenkins build.

      java.lang.AssertionError: create_write should create the file
      	at org.junit.Assert.fail(Assert.java:88)
      	at org.junit.Assert.assertTrue(Assert.java:41)
      	at org.apache.hadoop.hdfs.TestNNBench.testNNBenchCreateReadAndDelete(TestNNBench.java:55)
      

      Below is my analysis for why it didn't create the file.

      NNBench.java
      // Some comments here
        public void map(Text key, 
                  LongWritable value,
                  OutputCollector<Text, Text> output,
                  Reporter reporter) throws IOException {
            if (barrier()) {
              String fileName = "file_" + value;
              if (op.equals(OP_CREATE_WRITE)) {
                startTimeTPmS = System.currentTimeMillis();
                doCreateWriteOp(fileName, reporter);
              } ...
            } else {
              output.collect(new Text("l:latemaps"), new Text("1"));
            }
        // Below are the relevant parts of barrier() method
        private boolean barrier() {
          ..
          // If the sleep time is greater than 0, then sleep and return
          ...
          LOG.info("Waiting in barrier for: " + sleepTime + " ms");
          return retVal;
        }
        // Below are the relevant parts of the doCreateWriteOp
        private void doCreateWriteOp(String name,
                                       Reporter reporter) {
          FSDataOutputStream out;
          byte[] buffer = new byte[bytesToWrite];  
          for (long l = 0l; l < numberOfFiles; l++) {
            Path filePath = new Path(new Path(baseDir, dataDirName), 
                    name + "_" + l);
          }
        ....
        }
      

      This file BASE_DIR/data/file_0_0 is getting created only if the map task starts before the time mentioned by startTime.
      Refer the chunk which I pasted above.
      map(..) --> barrier() and only if barrier() evaluates to true it will call doCreateWriteOp which will eventually create the file.
      In test case, the delay value is 3 seconds as per "-startTime", "" + (Time.now() / 1000 + 3)
      In this failing test case, I can see the task starting minimum 6 seconds after the test case started.

      2017-01-27 03:11:15,387 INFO  [Thread-4] mapreduce.JobSubmitter (JobSubmitter.java:printTokens(289)) - Submitting tokens for job: job_local1711545156_0001
      2017-01-27 03:11:23,405 INFO  [Thread-4] mapreduce.Job (Job.java:submit(1345)) - The url to track the job: http://localhost:8080/
      

      Also when I run this test on my laptop, I see the following line being printed.

      2017-01-27 17:09:27,982 INFO  [LocalJobRunner Map Task Executor #0] hdfs.NNBench (NNBench.java:barrier(676)) - Waiting in barrier for: 1018 ms
      

      This line will be printed only in barrier() method and I don't see this line in the logs of failed test.

       
      In our environment, the jenkins server was very slow and it took more than 6 seconds to launch a map task.
      The correct fix in my opinion would be to return true in case there is no sleep in barrier() method. Only in exception, it should return false.

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              • Assignee:
                pingsutw kevin su
                Reporter:
                shahrs87 Rushabh Shah
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                • Created:
                  Updated:
                  Resolved: