PreloadSlowThings is called before Nuwa freeze now. This function produces many asynchronous messages from parent to frozen Nuwa. For a short term solution, we can move the code of invoking PreloadSlowThings to the new process forked from Nuwa.

Comment on attachment 8340316 [details] [diff] [review] Proposed Patch >From 3318c7156999b60f35ec2c6acfedfd10034f279f Mon Sep 17 00:00:00 2001 >From: Patrick Wang <kk1fff@patrickz.net> >Date: Fri, 29 Nov 2013 17:28:54 +0800 >Subject: [PATCH 5/5] Move common initialization routine into a function and > invoke PreloadSlowThings after nuwa forked > >--- > dom/ipc/ContentChild.cpp | 27 ++++--- > dom/ipc/ContentParent.cpp | 188 ++++++++++++++++++++++++--------------------- > dom/ipc/ContentParent.h | 5 ++ > 3 files changed, 122 insertions(+), 98 deletions(-) > >diff --git a/dom/ipc/ContentChild.cpp b/dom/ipc/ContentChild.cpp >index fd558e1..b55eb0f 100644 >--- a/dom/ipc/ContentChild.cpp >+++ b/dom/ipc/ContentChild.cpp >@@ -1362,17 +1351,31 @@ ContentChild::RecvAppInfo(const nsCString& version, const nsCString& buildID, > mAppInfo.UAName.Assign(UAName); > // If we're part of the mozbrowser machinery, go ahead and start > // preloading things. We can only do this for mozbrowser because > // PreloadSlowThings() may set the docshell of the first TabChild > // inactive, and we can only safely restore it to active from > // BrowserElementChild.js. > if ((mIsForApp || mIsForBrowser) && > Preferences::GetBool("dom.ipc.processPrelaunch.enabled", false)) { >- PreloadSlowThings(); >+#ifdef MOZ_NUWA_PROCESS >+ if (IsNuwaProcess()) { >+ // Perform GC before freezing the Nuwa process to reduce memory usage. >+ ContentChild::GetSingleton()->RecvGarbageCollect(); >+ >+ MessageLoop::current()-> >+ PostTask(FROM_HERE, >+ NewRunnableFunction(OnFinishNuwaPreparation)); >+ } else { >+ // This is a forked process, do preloading here. >+ PreloadSlowThings(); >+ } >+#else // !MOZ_NUWA_PROCESS >+ PreloadSlowThings(); >+#endif > } > return true; > } > I will prefer if ((mIsForApp || mIsForBrowser) && Preferences::GetBool("dom.ipc.processPrelaunch.enabled", false) #ifdef MOZ_NUWA_PROCESS && !IsNuwaProcess() #endif ) { PreloadSlowThings(); } And also, posting a delayed task should be moved out of the if block.

As discussion on bug 941466, this would be a short term solution to make Nuwa enabled on try server.

Have we measured how much this increases memory consumption (USS specifically) in the forked processes? Do we have a bug on file on undoing this and fixing it correctly?

I guess those measurements are in bug 941466.

Comment on attachment 8341603 [details] [diff] [review] Part 2: don't call PreloadSlowThings before nuwa fork. Review of attachment 8341603 [details] [diff] [review]: ----------------------------------------------------------------- ::: dom/ipc/ContentChild.cpp @@ +1363,5 @@ > PreloadSlowThings(); > } > + > +#ifdef MOZ_NUWA_PROCESS > + if (Preferences::GetBool("dom.ipc.processPrelaunch.enabled", false) && This is nit picky, but I would move this up further and do if (!Preferences::GetBool(...)) { return true; } if ((mIsForApp .... ... #ifdef MOZ_NUWA_PROCESS ...

(In reply to Kyle Huey [:khuey] (khuey@mozilla.com) from comment #8) > I guess those measurements are in bug 941466. Yes, they are. And bug 941466 is tracking the work for making the preloading work properly as well.

https://hg.mozilla.org/integration/b2g-inbound/rev/9275a2efc9e3 https://hg.mozilla.org/integration/b2g-inbound/rev/a21b57c78253

https://hg.mozilla.org/mozilla-central/rev/9275a2efc9e3 https://hg.mozilla.org/mozilla-central/rev/a21b57c78253

Backed out in https://hg.mozilla.org/mozilla-central/rev/06b3a7aea2c0 for frequent (somewhere between 20 and 50%) xpcshell shutdown crashes like https://tbpl.mozilla.org/php/getParsedLog.php?id=31651189&tree=B2g-Inbound

https://hg.mozilla.org/integration/b2g-inbound/rev/da8c926f7e4d https://hg.mozilla.org/integration/b2g-inbound/rev/e6b52f9d4138

https://hg.mozilla.org/mozilla-central/rev/da8c926f7e4d https://hg.mozilla.org/mozilla-central/rev/e6b52f9d4138

1.3+ for rel eng.

https://hg.mozilla.org/releases/mozilla-aurora/rev/2e63dfbf3661 https://hg.mozilla.org/releases/mozilla-aurora/rev/252715dcde18

status-b2g-v1.3T: fixed indicated that its in tarako. remove [tarako] whiteboard