Allen Wittenauer commented on YARN-3066:

So yes, it's still sealed off without a contract. Meh.

> Hadoop leaves orphaned tasks running after job is killed
> --------------------------------------------------------
>                 Key: YARN-3066
>                 URL: https://issues.apache.org/jira/browse/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 
> hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-nodemanager/src/main/java/org/apache/hadoop/yarn/server/nodemanager/DefaultContainerExecutor.java
>  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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