Go: Story of TryLock Function

Illustration created for “A Journey With Go”, made from the original Go Gopher, created by Renee French.

ℹ️ This article is based on Go 1.18.

Go 1.18 comes with a new function TryLock (for the mutexes sync.Mutex and sync.RWMutex) that allows the developer to try acquiring a lock in a non-blocking mode, i.e. if the lock is already acquired, the function will simply return the boolean false rather than waiting for the lock to be released.

This function piqued my curiosity because, although its name is explicit, its use cases are not obvious. Let’s collect information about it to better understand its usage.

Workflow

To better understand the workflow of a mutex, I suggest you read my article “Go: Mutex and Starvation.”

The lock of a mutex is not available if:

• the lock is currently held by another goroutine.
• the lock is not held but the mutex is in starvation mode; i.e., the lock will be handed off to the next waiter.

In either of these cases, the function TryLock will immediately return false. Here is a diagram that summarizes those two use cases:

TryLock function will return false.