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  1. Couchbase Server
  2. MB-49284

Performance: Plasma constructors shallow copy huge Config object many times

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    Description

      plasma.go constructors New(), New2(), New3() all accept argument cfg Config, which is a struct, therefore it is being passed by value not by reference. This means each call, and each child this is passed to that does the same thing, makes a new shallow copy of the entire Config struct. By my count this struct currently contains 113 fields, so these copies are doing a lot of extra CPU work and consuming significant stack.

      E.g. a call to New(cfg) triggers the following copies (at least the first 5, and possibly up to 7, assuming none of the great-grandchildren copy it further):

      1. New(cfg) – arg copied on call
      2. New2(cfg, ...) – copied to child call
      3. New3(cfg, ...) – copied to grandchild call
      4. applyConfigDefaults(cfg, ...) – copied to first great-grandchild call
      5. cfg = applyConfigDefaults(...) – and copied again assigning the returned copy back to New3's cfg variable
      6. doRecovery(..., cfg, ...) – copied to second great-grandchild if this call is made
      7. newPlasmaSkeleton(cfg, ...) – copied to third great-grandchild if this call is made

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        Activity

          kevin.cherkauer Kevin Cherkauer (Inactive) created issue -
          jliang John Liang made changes -
          Field Original Value New Value
          Assignee John Liang [ jliang ] Dmitriy Kalugin-Balashov [ dmitriy.kalugin-balashov ]
          jliang John Liang made changes -
          Labels plasma
          kevin.cherkauer Kevin Cherkauer (Inactive) made changes -
          Description plasma.go constructors *New(), New2(), New3()* all accept argument *cfg Config*, which is a struct, therefore it is being passed by value not by reference. This means each call, and each child this is passed to that does the same thing, makes a new shallow copy of the entire Config struct. By my count this struct currently contains 113 fields, so these copies are doing a lot of extra CPU work and consuming significant stack.

          E.g. a call to New(cfg) triggers the following copies (at least the first 5, and possibly up to 7, assuming none of the grandchildren copy it further):
           # New({color:#ff0000}*cfg*{color}) – arg copied on call
           # New2({color:#ff0000}*cfg*{color}, ...) – copied to child call
           # New3({color:#ff0000}*cfg*{color}, ...) – copied to grandchild call
           # applyConfigDefaults({color:#ff0000}*cfg*{color}, ...) – copied to first grandchild call
           # {color:#ff0000}*cfg*{color} = applyConfigDefaults(...) – and copied again assigning the returned copy back to New3's cfg variable
           # doRecovery(..., {color:#ff0000}*cfg*{color}, ...) – copied to second grandchild if this call is made
           # newPlasmaSkeleton({color:#ff0000}*cfg*{color}, ...) – copied to third grandchild if this call is made
          plasma.go constructors *New(), New2(), New3()* all accept argument *cfg Config*, which is a struct, therefore it is being passed by value not by reference. This means each call, and each child this is passed to that does the same thing, makes a new shallow copy of the entire Config struct. By my count this struct currently contains 113 fields, so these copies are doing a lot of extra CPU work and consuming significant stack.

          E.g. a call to New(cfg) triggers the following copies (at least the first 5, and possibly up to 7, assuming none of the great-grandchildren copy it further):
           # New({color:#ff0000}*cfg*{color}) – arg copied on call
           # New2({color:#ff0000}*cfg*{color}, ...) – copied to child call
           # New3({color:#ff0000}*cfg*{color}, ...) – copied to grandchild call
           # applyConfigDefaults({color:#ff0000}*cfg*{color}, ...) – copied to first great-grandchild call
           # {color:#ff0000}*cfg*{color} = applyConfigDefaults(...) – and copied again assigning the returned copy back to New3's cfg variable
           # doRecovery(..., {color:#ff0000}*cfg*{color}, ...) – copied to second great-grandchild if this call is made
           # newPlasmaSkeleton({color:#ff0000}*cfg*{color}, ...) – copied to third great-grandchild if this call is made
          Dmitriy.Kalugin-Balashov Dmitriy Kalugin-Balashov made changes -
          Status Open [ 1 ] In Progress [ 3 ]
          Dmitriy.Kalugin-Balashov Dmitriy Kalugin-Balashov made changes -
          Resolution Fixed [ 1 ]
          Status In Progress [ 3 ] Resolved [ 5 ]
          ritam.sharma Ritam Sharma made changes -
          Labels plasma plasma request-dev-verify
          srinath.duvuru Srinath Duvuru made changes -
          Status Resolved [ 5 ] Closed [ 6 ]

          People

            Dmitriy.Kalugin-Balashov Dmitriy Kalugin-Balashov
            kevin.cherkauer Kevin Cherkauer (Inactive)
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              Resolved:

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