Tuesday, March 1, 2016 [Tweets] [Favorites]

Tracking Tasks With Stack Traces in Swift

Matt Gallagher:

Instead of using log files to track asynchronous tasks, I prefer to use a structure that I call a “task journal”.

[…]

We’d have a bit more flexibility if we could use the C function backtrace but in Swift, we can’t. The backtrace function comes from the “execinfo.h” header and is implemented as part of libSystem on OS X and iOS (which all Swift programs link against) but for whatever reason, the “execinfo.h” contents are not exposed to Swift programs.

[…]

The resulting callStackReturnAddresses function is about twice as fast as NSThread.callStackReturnAddresses on the basic tests I’ve tried (roughly 2 million invocations per second per core on my Mac versus 1 million invocations per second for NSThread.callStackReturnAddresses). It’s easily fast enough to gather lots of data in Debug builds – even for fairly intensive computational paths.

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