How do I choose between Semaphore and SemaphoreSlim?

c# multithreading semaphore
Michael Hedgpeth picture Michael Hedgpeth · Nov 11, 2010 · Viewed 22.8k times · Source

Their public interfaces appear similar. The documentation states that the SemaphoreSlim is a lightweight alternative and doesn't use Windows Kernel semaphores. This resource states that the SemaphoreSlim is much faster. In what situations does the SemaphoreSlim make more sense over the Semaphore and vice versa?

Answer

Andrew Barber picture Andrew Barber · Nov 11, 2010

One difference is that SemaphoreSlim does not permit named semaphores, which can be system-wide. This would mean that a SemaphoreSlim could not be used for cross-process synchronization.

The MSDN documentation also indicates that SemSlim should be used when "wait times are expected to be very short". That would usually dovetail nicely with the idea that the slim version is more lightweight for most of the trade offs.

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