Enables disabling of old workers while allowing them to finish currently running tasks #1137
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LGTM, can you just fix the small comment on variable name? |
When updating worker code, I often want to kill the currently running workers so that they won't run the old code anymore. However, I'm usually ok with them finishing what they're currently working on, as that will often include long running jobs that aren't related to the changes I'm deploying. Killing these jobs throws away a lot of work. Instead, we can send SIGUSR1 to the worker and it will stop requesting new work and die when it's done running its current jobs.
I only want one assistant running at a time, and I want it running the latest code. In order to simplify deployment of new assistants, this adds a --take-lock command-line argument which will have the worker send SIGUSR1 to all other workers being run with the same command. This prevents other assistants run on the same machine with the same command from getting new jobs after this one starts. I've been using this to launch a new assistant alongside code deploys in order to ensure that old code stops getting run.
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Fixed the variable name. |
Tarrasch
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Aug 17, 2015
Enables disabling of old workers while allowing them to finish currently running tasks
This was referenced Oct 29, 2015
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This PR is split into two commits. The first one adds a signal handler for SIGUSR1 to workers, which prevents them from calling get_work. This allows old workers to be replaced without killing currently running tasks. By doing this, we prevent old code from being run going forward without losing progress on long-running tasks.
The second commit adds a --take-lock argument that causes a job to send SIGUSR1 to jobs that would otherwise occupy its lock. I've been using this successfully with an assistant that is automatically run with code deploys to ensure that the latest code is always being run without continuous deployment constantly killing all of my jobs.