[MAPREDUCE-3693] Add admin env to mapred-default.xml

• Type: Improvement
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 0.23.0
• Fix Version/s: 0.23.1
• Component/s: mrv2
• Target Version/s: 0.23.1
• Hadoop Flags: Reviewed
• Assignee: Roman Shaposhnik
• Reporter: Roman Shaposhnik
• Created: 19/Jan/12 02:32
• Updated: 28/Mar/12 21:57
• Resolved: 27/Jan/12 08:51

Description

I have noticed that org.apache.hadoop.mapred.MapReduceChildJVM doesn't forward the value of -Djava.library.path= from the parent JVM to the child JVM. Thus if one wants to use native libraries for compression the only option seems to be to manually include relevant java.library.path settings into the mapred-site.xml (as mapred.[map|reduce].child.java.opts).

This seems to be a change in behavior compared to MR1 where TaskRunner.java used to do that:

String libraryPath = System.getProperty("java.library.path");
    if (libraryPath == null) {
      libraryPath = workDir.getAbsolutePath();
    } else {
      libraryPath += SYSTEM_PATH_SEPARATOR + workDir;
    }
    boolean hasUserLDPath = false;
    for(int i=0; i<javaOptsSplit.length ;i++) {
      if(javaOptsSplit[i].startsWith("-Djava.library.path=")) {
        javaOptsSplit[i] += SYSTEM_PATH_SEPARATOR + libraryPath;
        hasUserLDPath = true;
        break;
      }
    }
    if(!hasUserLDPath) {
      vargs.add("-Djava.library.path=" + libraryPath);
    }
    for (int i = 0; i < javaOptsSplit.length; i++) {
      vargs.add(javaOptsSplit[i]);
    }

Is this a regression or a deliberate choice?

Issue Links

• relates to: MAPREDUCE-4072 User set java.library.path seems to overwrite default creating problems native lib loading