Non-reentrant functions used after thread suspend

[noahsmartin]

In the Swift version of Tracer, which is not used in production yet, there are some calls to functions that are not async signal safe like dladdr as well as heap allocations. The function getCallStack should be reentrant to avoid deadlocks:

ETTrace/ETTrace/TracerSwift/ThreadHelper.swift

Line 82 in f791b54

static func getCallStack(_ threadId: thread_t) -> [StackFrame]? {

The symbolication step should happen after threads are resumed, and we need to be careful not to allocate any memory on the heap while a thread is suspended, probably that portion of code should be in C since allocations can't be guaranteed to be avoided in Swift

[michaeleisel]

Would it make sense to merge this one with the C++ one?

[noahsmartin]

I think so - not exactly clear why the Swift one was added @Itaybre might know

[Itaybre]

This was created for Snapshots, since that project was already in Swift, I used that.
Didn't realize it could add issues with the threads

[noahsmartin]

This is fixed by #100