Dmitry Sivachenko created YARN-3066:
Summary: Hadoop leaves orphaned tasks running after job is killed
Project: Hadoop YARN
Issue Type: Bug
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
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
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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