WCF. Overhead of ConcurrencyMode.Multiple

I have a WCF service which is used synchronously, but its ConcurrencyMode is set to ConcurrencyMode.Multiple value, because the service is stat开发者_JAVA技巧eless actually. How much overhead does this mode impose? Does it make sense to change the mode to ConcurrencyMode.Single?

It doesn't really impose any overhead - other than the fact that the single service instance must handle concurrent access, it has to be 200% thread safe - and that's fairly tricky programming.

Switching to ConcurrencyMode.Single makes programming it simpler - no more worries about concurrency in the service class. But it serializes all requests - only one at a time can ever be handled and thus will become a performance bottleneck quickly.

You mention your service is stateless - so why not make it use the usually agreed upon best practice - not a singleton, but a regular "per-call" service class. In that mode, each request gets a fresh new instance of your service class, there's no fussing about multithreaded programming needed (all the multithreading is handled by the WCF runtime), you get concurrent handling of multiple requests - to me, that's only benefits and no down sides!