Something has to drain blocks sent to the main queue.
You can run a Foundation run loop. That should drain the main queue. I believe
it also ensures blocks sent to the main queue always run on the main thread.
Dispatch includes its own lower-level function to pump the main queue:
Is https://github.com/apple/swift/blob/master/utils/symbolicate-linux-fatal not
working for you?
This script works around the unfortunate interaction between dladdr and ELF
local symbols. It was added a year ago. The explanation is in the SR, and the
PR with the workaround was linked from the
