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  1. Bitbucket Data Center
  2. BSERV-19649

Adaptive throttling for memory usage

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    • Git Hosting
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    • We collect Bitbucket feedback from various sources, and we evaluate what we've collected when planning our product roadmap. To understand how this piece of feedback will be reviewed, see our Implementation of New Features Policy.

      Bitbucket's adaptive throttling sub-system is a system protection mechanism that uses a ticketing system whereby "heavyweight" Git hosting operations (such as clone/fetch/push) are throttled. That is, when the system is too busy to handle a Git hosting operation immediately it will queue the request, then after 5 minutes if that request didn’t make it to the front of the queue and get executed, it will be rejected.

      The data that is included in this dynamic throttling includes:

      • Number of CPU cores
      • %CPU usage
      • Total system memory
      • Various constraints that can be tuned

      One of the more commonly used tunables used is `throttle.resource.scm-hosting.adaptive.limit.max`. This this sets the upper limit on the number of SCM hosting operations, meaning pushes and pulls over HTTP or SSH, which may be running concurrently.

      A common reason for doing this is if a system has insufficient memory relative to the size of the largest repositories. For such a system, if tuning is not carried out it is possible for the Git processes Bitbucket forks to exhaust system memory.

      A useful improvement to adaptive throttling would be to account for RAM in a dynamic manner, potentially taking into account:

      • Available RAM at the time the ticket is granted; not just total ram calculated when Bitbucket starts; and/or
      • Average or maximum RAM usage of forked Git processes for each ticket granted

      This doesn't eliminate the chance of an out-of-memory situation, because Bitbucket can't predict exactly how much memory a Git process may consume, but may reduce the chance of an out-of-memory condition occurring in a system that is not appropriately configured.

              Unassigned Unassigned
              behumphreys Ben Humphreys
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