Allow signal handling for Uv w/o 100% cpu usage

[duckboy81]

Ref #329

To be honest this could lend itself to its own Uv specific example file, but here's something that could work regardless of driver used.

Again, downside is that the end of code execution is not in the signal handling function, but sometime after the Loop::run() line.

[enumag]

Not a very good solution imo. Now the signal handler can't control the exit code.

[kelunik]

What happens if you cancel the signal watcher before existing? Did you look where exactly it hangs in probably an infinite loop causing the 100% CPU usage?

Suggested change

	Loop::onSignal(SIGINT, function () {
	print "Caught SIGINT, exiting..." . PHP_EOL;
	// Check for a Uv driver
	if (Loop::get() instanceof Amp\Loop\UvDriver) {
	// Stop the loop
	Loop::stop();
	// Cannot exit out of a UvDriver loop here, can only stop the loop
	return;
	}
	Loop::onSignal(SIGINT, function ($watcherId) {
	print "Caught SIGINT, exiting..." . PHP_EOL;
	Loop::cancel($watcherId);

[duckboy81]

Not sure where my comment ended up, so sorry if this is a double tap.

Just tried this code and it still seems to get stuck in a loop. I tried debugging it for a couple hours, but I didn't get anywhere. Xdebug seemed to dump the profiler data before it got stuck in the loop, which made me think it was a Uv lib problem. (trying without xdebug loaded results in the same problem)

[kelunik]

I can't reproduce 100% CPU usage, but I get a warning:

Press Ctrl+C to exit...
^CCaught SIGINT, exiting...
PHP Warning:  zend_signal: handler was replaced for signal (2) after startup in Unknown on line 0

[duckboy81]

I can't reproduce 100% CPU usage, but I get a warning:

Press Ctrl+C to exit...
^CCaught SIGINT, exiting...
PHP Warning:  zend_signal: handler was replaced for signal (2) after startup in Unknown on line 0

Using uv as the driver? (I've currently got uv 0.2.4-3 if it matters)

[kelunik]

Please try with the latest master of https://github.com/bwoebi/php-uv.

[duckboy81]

Please try with the latest master of https://github.com/bwoebi/php-uv.

Alright, give me a hot minute to try it.

PS: Thanks for being so active, you guys are awesome.

[duckboy81]

Please try with the latest master of https://github.com/bwoebi/php-uv.

Alright, give me a hot minute to try it.

PS: Thanks for being so active, you guys are awesome.

No luck. Same result.

I'm not sure this is worth putting too much work into unless someone else runs into the same issue. They can reference this conversation.

[kelunik]

Which PHP version do you use?

[duckboy81]

Using the following:

PHP 7.4.2 (cli) (built: Jan 21 2020 11:35:20) ( NTS )
Zend Engine v3.4.0, Copyright (c) Zend Technologies
with Zend OPcache v7.4.2, Copyright (c), by Zend Technologies

If I switch from uv to the native driver, no issues too.

[trowski]

Perhaps there's an issue in ext-uv when calling exit inside a watcher callback? Exit handling changed recently to throw an exception internally (not sure which PHP version this happened in).