Dash startup time can have a large delay

[Pat McGowan]

While testing fixes for bug #1578283 there was a large discrepancy in how long it took to initialize the scope contents from boot to boot. Often a black screen was shown for up to 10 secs followed by the scope icon then the content, total time well over 12 secs.

While there were some crash files at boot that was not consistent with the symptom

MX4 proposed v319

[Pat McGowan (pat-mcgowan)]

Black screen on unlock

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Paweł Stołowski (stolowski)]

There are two aspects of these symptomps:
1) black screen with Scopes icon is shown before Dash is loaded and started I believe;
2) white screen (blank) is shown when Dash is loaded and is getting initialized (scope-registry is queried for installed scopes, then first two scopes are loaded, queried & prepopulated to show content immediately after unclock).

Both cases are largely affected by the fact that many other processes are started at about the same time and the CPU gets pretty busy. The 2nd case may be impacted if scope uses network (or a slow backend); it's not normally visible unless you unlock really fast (immediately after unity8 start).

Attaching bootchart graph (data was collected on the BQ phone from 9 boot sequences).

I'm not ruling out any possibility for an improvement, but it's unlikely to be a single thing which suddenly improves the situation, but rather a bunch of smaller improvements here and there (such as perhaps re-arranging how things are initialized in unity8 or elsewhere?).