Introduction

• Jobs are executed with JS7 Agents that handle termination of jobs.
  • Shell Jobs and JVM Jobs are under Control of the Agent that reliably terminates running jobs.
  • Jobs implementing use of an SSH Client or use of the JS7 - JITL SSHJob cannot guarantee that a job's child processes are terminated as they are controlled by the SSHD server.
• Termination of jobs can be caused by users from the JOC Cockpit and can performed automatically if a job exceeds a given timeout.
  • As a prerequisite for termination by JOC Cockpit the Controller has to be connected to JOC Cockpit and the Agent has to be accessible to the Controller.

Termination of Jobs

Jobs can be terminated in one of the following ways:

• The job is configured with a timeout setting: if job execution exceeds the timeout then the job will be killed by the Agent.
• Jobs can be killed by use of the GUI operation and and by use of the JS7 - REST Web Service API:
  • The cancel/kill operation kills a running job and fails the order.
  • The suspend/kill operation kills a running job and suspends the order.
  • Failed and suspended orders can be resumed.

Terminating Jobs on Unix

In Unix environments jobs receive the following signals from the Agent:

• When a job should be killed then the Agent sends a SIGTERM signal.
  • This signal can be ignored or can be handled by a job. For shell scripts a trap can be defined to e.g. perform cleanup tasks such as disconnecting from a database or removing temporary files.
• The job configuration includes the Grace timeout setting:
  • The Grace Timeout duration is applied after a SIGTERM signal (corresponding to kill -15) has been sent by the Agent. This allows the job to terminate on its own, for example after some cleanup is performed.
  • Should the job still run after the specified Grace Timeout duration then the Agent sends a SIGKILL signal (corresponding to kill -9) that aborts the OS process.

Job scripts frequently spawn child processes that have to be killed accordingly to their parent process.

• By default the OS removes child processes if the parent process is killed. However, this mechanism is not applicable for all situations, depending on the way how child processes have been spawned.
• To reliably kill child processes the Agent makes use of the kill_task.sh script from its var_<port>/work directory.
  • This script retrieves the process tree of the job script and tries to kill any child processes.
• Though the Agent is platform independent it is evident that retrieval of a process tree does not necessarily use the same command (ps) and options for any Unixes.
  • The Agent therefore allows to specify an individual kill script from a command line option should the built-in kill_task.sh script not be applicable to your Unix platform.

Terminating Jobs on Windows

For Windows environments the following applies when terminating jobs:

• The Agent makes use of the kill_task.cmd script that is available from its var_<port>/work directory.
  • The script makes use of the taskkill command to kill the job's process and its children.
• An individual kill script can be specified with a command line option on Agent startup.