NSDateFormatter crashes when used from different threads

Question

We keep getting a random, weird crash with NSDateFormatter. The relevant stack trace is:

Program received signal:  “EXC_BAD_ACCESS”.
#0  0x00000         


        

Answer 1

I was experiencing weird crashes with _sigtramp which caused to application to appear locked up but still on the screen - completely obstructing the real root cause.

It turned out indeed that we introduced multi-thread data parsing which collided with the main GUI thread trying to parse dates using NSDateFormatter.

Putting some synchronization around the NSDateFormatter formatDate calls resolved the issues.