On and off I've been trying to figure out how to do hang detection in-application (at least from the user's point of view). Qualitatively what I'd like to do is have a process which runs sample(1) on the application after it's been unresponsive for more than a second or so. Basically, an in-app replacement for Spin Control. The problem I've been stuck on is: how do I tell?
There used to be Core Graphics SPI (CGSRegisterNotifyProc with a value of kCGSEventNotificationAppIsUnresponsive) for doing this, but it doesn't work anymore (either due to sandboxing or system-wide security changes, I can't tell which but it doesn't matter).
One thought I had was to have an XPC service which would expect to receive a checkin once per second from the host (via a timer set up by the host). If it didn't, it would start sample(1). This seems pretty heavyweight to me, since it means that once per second, I'm going to be consuming cycles to check in with the service. But I haven't been able to come up with a scheme that doesn't include some kind of check-in by the target process.
Are there any APIs or strategies that I could use to accomplish this? Or is there some entitlement which would allow the application to request "application became unresponsive"/"application became responsive" notifications from the window server?