Event loop is not working anymore on macOS Sierra

[szkrd]

Maybe I'm missing something: cloned the repo, npm i, npm start and I get an nsexception error. Tried to do a standalone hello world, but the same happened - I'm on OSX, Sierra, will give it a try on Arch too. Do I have to install something else, or is my node version unsupported?

szkurdi ~/Projects/sandbox/libui-node $ npm start

> libui-node@0.0.12 start /Users/szkurdi/Projects/sandbox/libui-node
> node examples/control-gallery.js

2016-11-20 20:29:38.703 node[6245:111927] *** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'nextEventMatchingMask should only be called from the Main Thread!'
*** First throw call stack:
(
	0   CoreFoundation                      0x00007fffd538048b __exceptionPreprocess + 171
	1   libobjc.A.dylib                     0x00007fffe9ae2cad objc_exception_throw + 48
	2   AppKit                              0x00007fffd369350c -[NSApplication(NSEvent) shouldBeTreatedAsInkEvent:] + 0
	3   nbind.node                          0x00000001043bd801 _Z10pollEventsPv + 273
	4   libsystem_pthread.dylib             0x00007fffea5d8aab _pthread_body + 180
	5   libsystem_pthread.dylib             0x00007fffea5d89f7 _pthread_body + 0
	6   libsystem_pthread.dylib             0x00007fffea5d8221 thread_start + 13
)
libc++abi.dylib: terminating with uncaught exception of type NSException
Abort trap: 6
szkurdi ~/Projects/sandbox/libui-node $ node --version
v7.1.0
szkurdi ~/Projects/sandbox/libui-node $ uname -a
Darwin Szabolcss-Air 16.1.0 Darwin Kernel Version 16.1.0: Thu Oct 13 21:26:57 PDT 2016; root:xnu-3789.21.3~60/RELEASE_X86_64 x86_64

Edit: yes, it works fine on Arch :)

[RockyF]

who to fix it?

[parro-it]

This is related to how the event loop is actually implemented by libui-node.

Actually, on macOS and linux libui-node spawn a background thread that does a blocking GUI system call to check if there is some GUI event pending. If there are any, it send a message to node main thread, that in turn process these events.

This blocking give libui-node a great speed boost compared to a polling one (that is still used on Windows), but it can on be done in a background thread.

This used to work until Yosemite, but after that Apple introduces a hard limitation that such a check for GUI event loop status can be done only in main thread.

There is a previous, more complicated implementation that used an undocumented macOS feature but work without background threads. I could try to restore it in next relase.

[mischnic]

Works now