Dmitry Sivachenko created YARN-3066:

             Summary: Hadoop leaves orphaned tasks running after job is killed
                 Key: YARN-3066
             Project: Hadoop YARN
          Issue Type: Bug
          Components: nodemanager
         Environment: Hadoop 2.4.1 (probably all later too), FreeBSD-10.1
            Reporter: Dmitry Sivachenko

When spawning user task, node manager checks for setsid(1) utility and spawns 
task program via it. See 
 for instance:

String exec = Shell.isSetsidAvailable? "exec setsid" : "exec";

FreeBSD, unlike Linux, does not have setsid(1) utility.  So plain "exec" is 
used to spawn user task.  If that task spawns other external programs (this is 
common case if a task program is a shell script) and user kills job via mapred 
job -kill <Job>, these child processes remain running.

1) Why do you silently ignore the absence of setsid(1) and spawn task process 
via exec: this is the guarantee to have orphaned processes when job is 
prematurely killed.
2) FreeBSD has a replacement third-party program called ssid (which does almost 
the same as Linux's setsid).  It would be nice to detect which binary is 
present during configure stage and put @SETSID@ macros into java file to use 
the correct name.

I propose to make Shell.isSetsidAvailable test more strict and fail to start if 
it is not found:  at least we will know about the problem at start rather than 
guess why there are orphaned tasks running forever.

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