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https://issues.apache.org/jira/browse/MAPREDUCE-2236?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Harsh J Chouraria updated MAPREDUCE-2236:
-----------------------------------------
Attachment: MAPREDUCE-2236.r1.diff
Patch that caps maximum attempts at 100.
> No task may execute due to an Integer overflow possibility
> ----------------------------------------------------------
>
> Key: MAPREDUCE-2236
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-2236
> Project: Hadoop Map/Reduce
> Issue Type: Bug
> Affects Versions: 0.20.2
> Environment: Linux, Hadoop 0.20.2
> Reporter: Harsh J Chouraria
> Assignee: Harsh J Chouraria
> Priority: Critical
> Fix For: 0.23.0
>
> Attachments: MAPREDUCE-2236.r1.diff
>
>
> If the attempts is configured to use Integer.MAX_VALUE, an overflow occurs
> inside TaskInProgress, and thereby no task is attempted by the cluster and
> the map tasks stay in pending state forever.
> For example, here's a job driver that causes this:
> {code}
> import java.io.IOException;
> import org.apache.hadoop.fs.FSDataOutputStream;
> import org.apache.hadoop.fs.FileSystem;
> import org.apache.hadoop.fs.Path;
> import org.apache.hadoop.mapred.FileInputFormat;
> import org.apache.hadoop.mapred.JobClient;
> import org.apache.hadoop.mapred.JobConf;
> import org.apache.hadoop.mapred.TextInputFormat;
> import org.apache.hadoop.mapred.lib.IdentityMapper;
> import org.apache.hadoop.mapred.lib.NullOutputFormat;
> @SuppressWarnings("deprecation")
> public class IntegerOverflow {
> /**
> * @param args
> * @throws IOException
> */
> @SuppressWarnings("deprecation")
> public static void main(String[] args) throws IOException {
> JobConf conf = new JobConf();
>
> Path inputPath = new Path("ignore");
> FileSystem fs = FileSystem.get(conf);
> if (!fs.exists(inputPath)) {
> FSDataOutputStream out = fs.create(inputPath);
> out.writeChars("Test");
> out.close();
> }
>
> conf.setInputFormat(TextInputFormat.class);
> conf.setOutputFormat(NullOutputFormat.class);
> FileInputFormat.addInputPath(conf, inputPath);
>
> conf.setMapperClass(IdentityMapper.class);
> conf.setNumMapTasks(1);
> // Problem inducing line follows.
> conf.setMaxMapAttempts(Integer.MAX_VALUE);
>
> // No reducer in this test, although setMaxReduceAttempts leads
> to the same problem.
> conf.setNumReduceTasks(0);
>
> JobClient.runJob(conf);
> }
> }
> {code}
> The above code will not let any map task run. Additionally, a log would be
> created inside JobTracker logs with the following information that clearly
> shows the overflow:
> {code}
> 2010-12-30 00:59:07,836 WARN org.apache.hadoop.mapred.TaskInProgress:
> Exceeded limit of -2147483648 (plus 0 killed) attempts for the tip
> 'task_201012300058_0001_m_000000'
> {code}
> The issue lies inside the TaskInProgress class
> (/o/a/h/mapred/TaskInProgress.java), at line 1018 (trunk), part of the
> getTaskToRun(String taskTracker) method.
> {code}
> public Task getTaskToRun(String taskTracker) throws IOException {
> // Create the 'taskid'; do not count the 'killed' tasks against the job!
> TaskAttemptID taskid = null;
> /* ============ THIS LINE v ====================================== */
> if (nextTaskId < (MAX_TASK_EXECS + maxTaskAttempts + numKilledTasks)) {
> /* ============ THIS LINE ^====================================== */
> // Make sure that the attempts are unqiue across restarts
> int attemptId = job.getNumRestarts() * NUM_ATTEMPTS_PER_RESTART +
> nextTaskId;
> taskid = new TaskAttemptID( id, attemptId);
> ++nextTaskId;
> } else {
> LOG.warn("Exceeded limit of " + (MAX_TASK_EXECS + maxTaskAttempts) +
> " (plus " + numKilledTasks + " killed)" +
> " attempts for the tip '" + getTIPId() + "'");
> return null;
> }
> {code}
> Since all three variables being added are integer in type, one of them being
> Integer.MAX_VALUE makes the condition fail with an overflow, thereby logging
> and returning a null as the result is negative.
> One solution would be to make one of these variables into a long, so the
> addition does not overflow?
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