New timerFunc in rc7 is laggy

[xelia]

New timerFunc in rc7 intoduced random lags and 100-1000ms delays before nexttick happens in my application where old timerFunc in rc6 worked just fine.

[posva]

Well, that's definitely a shame. Please follow the Issue Reporting Guidelines and provide a minimal JSFiddle or JSBin containing a set of reproducible steps that can lead to the behaviour you described.

[xelia]

Looks like window.postMessage in chromium sometimes has random delays. The problem is it happens with about 10% chance on my project and i still havent found reliable way to reproduce it.

[posva]

If that's the case, it may be a bug with chromium. Have you tried on a stable version of any other browser?

[xelia]

Delays reproduce in chromium based browsers(chrome, opera). There is no delays in firefox. Have not tried IE yet.

[posva]

That's a starting point for a repro

[wonderful-panda]

I faced similar problem too in Windows 10 / Chrome 53.0.2785.116 m (64-bit).

rc6: https://jsfiddle.net/k6bgu2z6/4/
rc7: https://jsfiddle.net/v9q9L0hw/2/

In the rc6's example, yellow square don't move when scrolling container element.
In the rc7's one, yellow square swings vertically when scrolling.

1.0.27 has same problem.

[xelia]

Well, that reproduction is only part of my problem(small lag), sometimes delay gets bigger. But its still same problem.

[yyx990803]

Sigh, we may need to revert this...

The primary reason I changed the implementation is because MutationObserver (which is the original implementation) is buggy in iOS UIWebView >= 9.3.3 - it simply breaks after scrolling the page for a bit. However in iOS10 sniffing it apart from other environments like WKWebView and native iOS Safari is extremely tricky.

1.0.27 / 2.0.0-rc.7 uses a setImmediate shim using window.postMessage, which uses the macrotask queue instead of the microtask queue (used by MutationObserver). The difference being that macrotasks are queued after current browser rendering/IO jobs (e.g. repaint on scroll event) while microtasks are queued before that. This leads to the behavior seen in @wonderful-panda 's jsfiddles and the delays seen by @xelia (most likely associated with heavy repaints on scroll).

I guess we will have to revert to MutationObserver with more UIWebView sniffing...