RFR (XS): 8236177: assert(status == 0) failed: error ETIMEDOUT(60), cond_wait

[Kim Barrett]

> On May 1, 2020, at 4:59 PM, gerard ziemski <gerard.ziemski at oracle.com> wrote:
> In the fix I introduce MAC_ONLY() macro, as per David's suggestion.
> 
> bug link at https://bugs.openjdk.java.net/browse/JDK-8236177
> open webrev at http://cr.openjdk.java.net/~gziemski/8236177_rev3
> testing: Mach hs-tier1,2,3,4,5 in progress…

I think the macro name should be MACOS_ONLY, as David suggested.

Other than that, this looks good. And thanks for filing the bug with Apple.

The changes to PlatformEvent::park and PlatformParker::park made me
wonder why we don't have the same Apple-specific problem with the
pthread_mutex/condvars there that we had with PlatformMutex/Monitor.
It seems we dodged that because ParkEvent/Parker were already using a
free-list allocator.