2.12 About How Condor Jobs Vacate Machines

  When Condor needs a job to vacate a machine for whatever reason, it sends the job an asynchronous signal specified in the KillSig attribute of the job's ClassAd. The value of this attribute can be specified by the user at submit time by placing the kill_sig option in the Condor submit description file.

If a program wanted to do some special work when required to vacate a machine, the program may set up a signal handler to use a trappable signal as an indication to clean up. When submitting this job, this clean up signal is specified to be used with kill_sig. Note that the clean up work needs to be quick. If the job takes too long to go away, Condor follows up with a SIGKILL signal which immediately terminates the process.

  A job that is linked using condor_compile and is subsequently submitted into the standard universe, will checkpoint and exit upon receipt of a SIGTSTP signal. Thus, SIGTSTP is the default value for KillSig when submitting to the standard universe. The user's code may still checkpoint itself at any time by calling one of the following functions exported by the Condor libraries:

ckpt()

Performs a checkpoint and then returns.

ckpt_and_exit()

Checkpoints and exits; Condor will then restart the process again later, potentially on a different machine.

For jobs submitted into the vanilla universe, the default value for KillSig is SIGTERM, the usual method to nicely terminate a Unix program.