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  1. C# Driver
  2. CSHARP-2556

Reduce memory allocations in BsonSerializerRegistry.GetSerializer()

    • Type: Icon: Improvement Improvement
    • Resolution: Unresolved
    • Priority: Icon: Major - P3 Major - P3
    • None
    • Affects Version/s: 2.8.0
    • Component/s: Performance, Serialization
    • None
    • Fully Compatible
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      1. What would you like to communicate to the user about this feature?
      2. Would you like the user to see examples of the syntax and/or executable code and its output?
      3. Which versions of the driver/connector does this apply to?

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      1. What would you like to communicate to the user about this feature? 2. Would you like the user to see examples of the syntax and/or executable code and its output? 3. Which versions of the driver/connector does this apply to?

      The BsonSerializerRegistry.GetSerializer() gets called repeatedly on the hot path during serialization/deserialization. It allocates memory due to an implicit closure of the current instance variable ("this").

      This allocation can be avoided.

      For the versions of the .NET frameworks which we are dealing with (.NET 4.5.2/.NET Standard 1.5) the following approach would work: https://github.com/dotnet/corefx/issues/394

      From .NET 4.7.2 onwards it is possible to simply switch to a special overload of the ConcurrentDictionary.GetOrAdd() method which accepts a factory argument as described here https://github.com/dotnet/corefx/pull/1783 and documented here (https://docs.microsoft.com/en-us/dotnet/api/system.collections.concurrent.concurrentdictionary-2.getoradd?view=netframework-4.7.2#System_Collections_Concurrent_ConcurrentDictionary_2_GetOrAdd__1__0_System_Func__0___0__1____0_)

            Assignee:
            Unassigned Unassigned
            Reporter:
            daniel.hegener@gmx.net Daniel Hegener
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              Created:
              Updated: