Hi, I recently found out, while refactoring some parts of `make package`, that since Firefox 38, we've stopped shipping startup cache data for all the browser javascript modules and components. This turned out to be the consequence of resource://app/ having been overridden to point somewhere different from where it's supposed to point to.
I landed a fix for this issue this morning (bug 1224000 ; the fun part is that it uncovered another bug: bug 1226119) Anyways, there are three things that I take out of this: - Startup cache is either useless, or we failed to measure the startup time regression in Firefox 38. Either way, something should be done: either we don't need the startup cache anymore and we should plain remove it, or talos should catch such regressions if they exist. I guess we'll see if talos catches some improvements on the fix... Can the perf team look into this? Note the startup cache only matters on the first startup for a given build, and that might be a reason why we fail to track its performance impact. - resource:///, resource://gre/ and resource://app/, which are used by chrome code and possibly addons, are not fixed in stone and can be replaced by mistake. This should not be possible, and I filed bug 1225384 for that (patch pending review). - The change of meaning for resource://app/ may inadvertently have broken addons relying on it, and if it did, it's a problem that we haven't gotten aware of it earlier. ISTR we can do code search on addons, but I never know where to look for this. Most code in Firefox itself fortunately uses resource:/// instead of resource://app/ (they have the same meaning, or at least were supposed to, since the bug broke this promise), so it was fortunately not a direct problem for Firefox itself. There's kind of a 4th item to add to the list: that we can have missing startup cache is also a problem on itself, but it's really tied to the second issue, since the startup cache generation script relies on resource://app/ resolving to what it's supposed to in the first place. Cheers, Mike _______________________________________________ dev-platform mailing list dev-platform@lists.mozilla.org https://lists.mozilla.org/listinfo/dev-platform
