objectForKey:block: fails to call completion block when asked to process "large" numbers of requests about tmcache

[jstn]

Great catch, thank you!

What's happening is that GCD is hitting its thread limit (~= 64). Here's some brief discussion:
http://stackoverflow.com/questions/7213845/number-of-threads-created-by-gcd

Basically, TMCache has been using TMMemoryCache with a synchronous call to objectForKey:, which should theoretically be fine because it's happening on another queue (that is, until it's waiting for more objects than there are threads and they all get blocked).

The fix was to switch everything in objectForKey: to asynchronous calls, which is messier but ultimately safer and avoids this problem. I've also added a unit test to hopefully catch this if it happens in the future. Here's the commit: e44251f

[prendio2]

Thanks so much @jstn for resolving this so quickly and letting me know what was going wrong. Glad I could help in some small way.