Relative performance of ReaderWriterLockSlim


I’ve recently wanted to demonstrate the relevance of the .Net ReaderWriterLock[Slim] synchronization primitives.
It’s good to hear from the vendor that it’s better, faster, stronger, but when you can it’s always good to evaluate it yourself; not that I don’t trust vendors, but because I like to have hard numbers, particularly when I assert something that can be critical for my participants’ developments.

So I’ve built a small, simple and I hope relevant benchmark to measure the performance impact of ReaderWriterLock[Slim] compared to the naive and uniform use of a Monitor using the C# lock construct.

I wanted to check these two things:

  • that the RW locks behave as advertised,
  • what is the profile of the gain function.

In this article I’ll explain the rationales behind the benchmark, how I’ve implemented it and finally present the results.

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