2015-04-26 12:48:37 +05:30
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# Sidekiq MemoryKiller
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The GitLab Rails application code suffers from memory leaks. For web requests
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this problem is made manageable using
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[unicorn-worker-killer](https://github.com/kzk/unicorn-worker-killer) which
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restarts Unicorn worker processes in between requests when needed. The Sidekiq
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MemoryKiller applies the same approach to the Sidekiq processes used by GitLab
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to process background jobs.
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Unlike unicorn-worker-killer, which is enabled by default for all GitLab
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installations since GitLab 6.4, the Sidekiq MemoryKiller is enabled by default
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_only_ for Omnibus packages. The reason for this is that the MemoryKiller
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relies on Runit to restart Sidekiq after a memory-induced shutdown and GitLab
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installations from source do not all use Runit or an equivalent.
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With the default settings, the MemoryKiller will cause a Sidekiq restart no
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more often than once every 15 minutes, with the restart causing about one
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minute of delay for incoming background jobs.
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## Configuring the MemoryKiller
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The MemoryKiller is controlled using environment variables.
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- `SIDEKIQ_MEMORY_KILLER_MAX_RSS`: if this variable is set, and its value is
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greater than 0, then after each Sidekiq job, the MemoryKiller will check the
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RSS of the Sidekiq process that executed the job. If the RSS of the Sidekiq
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process (expressed in kilobytes) exceeds SIDEKIQ_MEMORY_KILLER_MAX_RSS, a
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delayed shutdown is triggered. The default value for Omnibus packages is set
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[in the omnibus-gitlab
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repository](https://gitlab.com/gitlab-org/omnibus-gitlab/blob/master/files/gitlab-cookbooks/gitlab/attributes/default.rb).
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- `SIDEKIQ_MEMORY_KILLER_GRACE_TIME`: defaults 900 seconds (15 minutes). When
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a shutdown is triggered, the Sidekiq process will keep working normally for
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another 15 minutes.
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- `SIDEKIQ_MEMORY_KILLER_SHUTDOWN_WAIT`: defaults to 30 seconds. When the grace
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time has expired, the MemoryKiller tells Sidekiq to stop accepting new jobs.
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Existing jobs get 30 seconds to finish. After that, the MemoryKiller tells
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Sidekiq to shut down, and an external supervision mechanism (e.g. Runit) must
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restart Sidekiq.
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2016-06-02 11:05:42 +05:30
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- `SIDEKIQ_MEMORY_KILLER_SHUTDOWN_SIGNAL`: defaults to `SIGKILL`. The name of
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2015-09-11 14:41:01 +05:30
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the final signal sent to the Sidekiq process when we want it to shut down.
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