1447393 - Keep content process alive even if there are no "tabs"

Status: RESOLVED FIXED

(GeckoView Graveyard :: Sandboxing, enhancement, P1)

Description

[James Willcox (:snorp) ([e-mail]) (he/him)]

Normally, ContentParent will shut down a content process once it is empty. This causes problems with GeckoView because:

1) GeckoView currently supports only one content process, due to the way they are hosted in the Service. We could expand this, but I also think we want to limit it to 1 for memory usage concerns.

2) When a process is abandoned in ContentParent, it is apparently not done synchronously. Consequently, when a new tab is created, we could be waiting for the old process to die when a new one is requested. This fails due to 1). It's also possible that process shut down is completely broken on Android right now, because it's not clear to me how it should be working.

It's possible to set dom.ipc.keepProcessesAlive.web to keep a content process alive even when it is empty. I think we should set that for now to avoid the above problem, pending a more robust solution.

Comment 1

[James Willcox (:snorp) ([e-mail]) (he/him)]

Attachment: Bug 1447393 - Keep empty content process alive on Android

Review commit: https://reviewboard.mozilla.org/r/229460/diff/#index_header
See other reviews: https://reviewboard.mozilla.org/r/229460/

Comment 2

[Blake Kaplan (:mrbkap) (inactive)]

Comment on attachment 8960704 [details]
Bug 1447393 - Keep empty content process alive on Android

https://reviewboard.mozilla.org/r/229460/#review235256

Seems reasonable to me.

Comment 3

[Jim Mathies [:jimm]]

Comment on attachment 8960704 [details]
Bug 1447393 - Keep empty content process alive on Android

https://reviewboard.mozilla.org/r/229460/#review235602

r- on the first issue raised here, easy to patch up.

So looking through here I see this comment which really needs to be removed if we're going to use this setting in production -
https://searchfox.org/mozilla-central/source/dom/ipc/ContentParent.cpp#1856
Also, I think you should turn off the preallocated process manager here for completelness. This code makes its decision to recycle here - 
https://searchfox.org/mozilla-central/source/dom/ipc/ContentParent.cpp#1815
The pref is 'dom.ipc.processPrelaunch.enabled'
code is here if you're curious - 
https://searchfox.org/mozilla-central/source/dom/ipc/PreallocatedProcessManager.cpp

Lastly, are you sure you want to do this? :) Child processes can accumulate a lot of cruft over time. It's a known issue and one of the reasons we recycle content processes on a regular basis.

Comment 4

[James Willcox (:snorp) ([e-mail]) (he/him)]

Comment on attachment 8960704 [details]
Bug 1447393 - Keep empty content process alive on Android

https://reviewboard.mozilla.org/r/229460/#review235602

Yeah, we do eventually want to have more content processes. For now we just want to try to make things stable.

Generally on Android, though, the app will die often enough that we won't have the same problems with a long-running content process. I think this should be especially true with Focus, the first GeckoView-using app.

Comment 5

[James Willcox (:snorp) ([e-mail]) (he/him)]

Comment on attachment 8960704 [details]
Bug 1447393 - Keep empty content process alive on Android

Review request updated; see interdiff: https://reviewboard.mozilla.org/r/229460/diff/1-2/

Comment 6

[Jim Mathies [:jimm]]

Comment on attachment 8960704 [details]
Bug 1447393 - Keep empty content process alive on Android

https://reviewboard.mozilla.org/r/229460/#review236180

Comment 7

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/mozilla-inbound/rev/4c6aa2c88102
Keep empty content process alive on Android r=jimm,mrbkap

Comment 8

[Cristina Coroiu [:ccoroiu]]

https://hg.mozilla.org/mozilla-central/rev/4c6aa2c88102

Comment 9

[Chris Peterson [:cpeterson]]

Moving content process management bugs to the new GeckoView::Sandboxing component.