How can I set a breakpoint on _NSLockError() [duplicate]

This question already has answers here: Break on _NSLockError() to debug ... How to? (3 answers) Closed 6 years ago.

I am trying to debug multiple threads.

 *** -[NSLock lock]: deadlock (<NSLock:开发者_如何学JAVA 0xc388ab0> '(null)')
 *** Break on _NSLockError() to debug.

How can I debug this?

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If you're using the Xcode debugger (which uses gdb under the hood), pause the app and in the console enter:

b _NSLockError

Then the debugger will stop the app when _NSLockError happens, which you should be able to check the backtrace.