899403 - set timeout for killing thumbnail browser to zero

Status: NEW

(Toolkit :: General, defect)

Description

[Mark Hammond [:markh] [:mhammond]]

The background thumbnail service uses a timeout after the last queued capture completes to kill the <browser> element.  The way this service is currently used (ie, only by about:newtab) and given some poor interactions with private browsing mode caused by this bug (eg, bug 899064), it makes sense to reduce this timeout to zero, so the browser is killed immediately after finishing the queue.  At this stage we will keep the timer code in place as we are likely to want it re-enabled later.

Comment 1

[Drew Willcoxon :adw]

Since it seems likely that this would lead to more frequent content process tear downs and spawns, both of which are expensive, I'm worried that this conflicts with our goal of reducing background thumbnailing impact.  But I don't have any data, and it would certainly depend on usage patterns.

Comment 2

[Mark Hammond [:markh] [:mhammond]]

(In reply to Drew Willcoxon :adw from comment #1)
> Since it seems likely that this would lead to more frequent content process
> tear downs and spawns, both of which are expensive, I'm worried that this
> conflicts with our goal of reducing background thumbnailing impact.  But I
> don't have any data, and it would certainly depend on usage patterns.

I was initially thinking that this might lessen the impact of bug 899064 - but I'm not sure that is the case - it seems the profiler might still not be usable after the browser is torn down.  I agree we should only do this if there is something concrete it solves.