MySQL get_lock('test_lock', 0) always returns 1

Craig Smith :

As I understand it, get_lock('test_lock', 0) should return 1, or success, after the first call. A second call should return 0. After a release_lock('test_lock') is called, it would return 1 again. Is that right? I'm just using MySQL Workbench to run the commands and getting back a 1 each time. I was hoping to use this lock as a semaphore in my application.

Mureinik :

Once you successfully call get_lock, your session owns it, so subsequent calls from the same session will also succeed (and return 1). If you run get_lock and then open another MySQL Workbench session (e.g., by launching another instance of the application) and try to obtain the same lock, it will fail (and return 0).

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