668634 - Discard decoded images in foreground tab on memory pressure

Status: RESOLVED WONTFIX

(Core :: Graphics: ImageLib, defect)

Description

[Justin Lebar (not reading bugmail)]

Split off from bug 666317 comment 9:

Bug 666317 makes us discard images in background tabs when we receive a memory-pressure notification.  We might also want to discard images in the foreground tab, because:

 * Android fires a memory-pressure notification when the app goes into the background.
 * A page might have many large images on one tab.

To plagiarize myself:

On desktop, if memory is low, we will fire low-memory notifications once a second.  Surely we don't want to drop all images and re-decode those in the viewport once a second, especially if we're paging and already running slowly.

Optimally, we'd discard all images except those in the viewport, but my understanding is that this is currently hard to do.

We could do something like drop foreground images on the first memory-pressure call within 60s, but then only drop background images on other memory-pressure notifications.

Comment 1

[lopardo]

BTW, this is tagged as "Me*n*Shrink". :P

Comment 2

[Nicholas Nethercote [inactive]]

The bugs depending on bug 689623 are likely to be much more effective for this kind of thing.