[YARN-8706] DelayedProcessKiller is executed for Docker containers even though docker stop sends a KILL signal after the specified grace period

• Type: Sub-task
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 3.2.0
• Labels: docker
• Target Version/s: 3.2.0
• Assignee: Chandni Singh
• Reporter: Chandni Singh
• Created: 23/Aug/18 20:52
• Updated: 14/Sep/18 16:12
• Resolved: 14/Sep/18 15:48

Description

DockerStopCommand adds a grace period of 10 seconds.

10 seconds is also the default grace time use by docker stop
https://docs.docker.com/engine/reference/commandline/stop/

Documentation of the docker stop:

the main process inside the container will receive SIGTERM, and after a grace period, SIGKILL.

There is a DelayedProcessKiller in ContainerExcecutor which executes for all containers after a delay when sleepDelayBeforeSigKill>0. By default this is set to 250 milliseconds and so irrespective of the container type, it will always get executed.

For a docker container, docker stop takes care of sending a SIGKILL after the grace period

• when sleepDelayBeforeSigKill > 10 seconds, then there is no point of executing DelayedProcessKiller
• when sleepDelayBeforeSigKill < 1 second, then the grace period should be the smallest value, which is 1 second, because anyways we are forcing kill after 250 ms

Issue Links

• is related to: YARN-7644 NM gets backed up deleting docker containers
• relates to: YARN-8744 In some cases docker kill is used to stop non-privileged containers instead of sending the signal directly