Bug 39285 - High CPU use on the Mac build host appears to cause UI pauses in paired instance of Visual Studio?
Summary: High CPU use on the Mac build host appears to cause UI pauses in paired insta...
Alias: None
Product: Visual Studio Extensions
Classification: Xamarin
Component: XMA ()
Version: 4.0.0 (C6)
Hardware: PC Windows
: Normal normal
Target Milestone: 15.4
Assignee: Bugzilla
Depends on:
Reported: 2016-03-02 03:37 UTC by Brendan Zagaeski (Xamarin Team, assistant)
Modified: 2017-07-28 13:08 UTC (History)
6 users (show)

Tags: papercut
Is this bug a regression?: ---
Last known good build:

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Description Brendan Zagaeski (Xamarin Team, assistant) 2016-03-02 03:37:26 UTC
High CPU use on the Mac build host appears to cause UI pauses in paired instance of Visual Studio?

Based on my initial casual observations, this seems to affect all the projects in the solution (not just iOS projects) as long as at least 1 iOS project is currently loaded.

## "Steps associated with replicating the problem"

- I noticed this behavior today while I was running some CPU intensive tasks (installing software, nothing specific to Xamarin) on the Mac build host.

- I was simultaneously doing some development in Visual Studio on a separate physical Windows machine that did not require the build host. Visual Studio had automatically paired itself with the Mac build host (because it had been paired previously).

## Results

- I noticed that Visual Studio was experiencing pauses and slow UI responsiveness.

- I explicitly disconnected Visual Studio from the build host. That seemed to improve Visual Studio's responsiveness significantly.

## Expected Results

If possible, perhaps the UI responsiveness of Visual Studio can be made less dependent on the CPU load of the Mac build host. Of course there are certain operations that absolutely _require_ the build host (like browsing the available simulators or the available provisioning profiles), so it's OK if those operations still experience pauses when the Mac build host is under high CPU load.


## Version info (brief)

### Visual Studio 2015 Update 1, Windows 10 64-bit
XamarinVS (dcea9c1)

### OS X 10.10.5
Xamarin.iOS (962a050)
Comment 1 Brendan Zagaeski (Xamarin Team, assistant) 2016-03-02 03:42:13 UTC
If I get a chance, I might try to characterize this issue in more precise detail another day, but my initial observations gave me the impression that this problem might be easy to replicate on other environments (e.g., on QA's machines or on the engineers' machines). So I figured it would be good to get a bug filed with this preliminary description, just in case I don't get a chance to come back to it soon, and in case it is indeed something that's easy to replicate locally and fix based on this initial description.
Comment 2 Daniel Cazzulino 2016-05-10 16:54:57 UTC
Yes, sounds like it should be straightforward to replicate. Thanks for reporting it!

Assigning to cycle8 milestone as part of the VS performance push.
Comment 3 Jon Goldberger [MSFT] 2016-05-13 21:35:13 UTC
This _may_ be related to bug 37170 and bug 39344
Comment 5 mag@xamarin.com 2017-01-02 13:49:32 UTC
Moving to future cycle for further investigation since it's probable that, after the performance improvements and fixes around XMA during 2016, this issue could have been fixed.
Comment 6 mag@xamarin.com 2017-06-08 16:26:30 UTC
I will consider this fixed for 15.4 release, since for that release a new version of XMA will be in place, with a big re design on many of its layers, as consequence of the Xamarin IoT feature.

XMA now is not tied to iOS anymore and it's a new separate component that enables to connect to any remote hosts and not only a Mac. With this re design, many issues has been fixed.

Also, the Designer Agent is not part of XVS anymore and acts as a separate component, not tied directly to XMA.

That said, and taking into account that I couldn't get any UI pause as consequence of Mac high CPU usage on the feature branch corresponding to 15.4 version, I consider this issue as Resolved.