Firefox Core Engineering

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The purpose of this team is to address needs that fall between Toolkit and Platform, with an emphasis (currently) on improving stability, quality, and performance – supported by empirical data. As such, we overlap a bit with everyone from Gecko, Desktop, Data, and more.

This team grew out of, in part, the Performance Engineering team, and owns some of that team's infrastructure – some performance-related dashboards on, crash analysis, hang visualization, etc. It also includes the installer & updater applications.


  • Neil Deakin (:enn)
  • Adam Gashlin (:agashlin)
  • Felipe Gomes (:felipe)
  • Matt Howell (:mhowell)
  • Chris HC (:chutten) -- honorary
  • Kirk Steuber (:bytesized)
  • Robert Strong (:rstrong)
  • Gabriele Svelto (:gsvelto)
  • Doug Thayer (:dthayer)
  • David Durst (:ddurst)


  1. Enabling stability
    In general, things we do should be tied to enabling stability – so, making it measurable and/or addressing issues.
  2. Supporting performance improvements
    Improving performance is certainly everyone's job—not just our team—but we hold the keys for some distinct historical pieces of the analysis that allow people to understand what needs to be improved. This is primarily, but not limited to, telemetry and data analysis.
  3. Improving the user/contributor experience
    This one is the weirdest: it covers things that we can do to further the web, and improve the experience for our users – both end users and code contributors (some examples: Flash blocking, XUL performance analysis). This category is the most open-ended for future expansion.


You can typically find us in:


  • #fce (primary)
  • #developers
  • #e10s
  • #fx-team
  • #perf
  • #releng
  • #telemetry
  • #uptime

Mailing lists

  • dev-platform
  • fhr-dev
  • firefox-dev

Process and Queuing

There is currently no regimented process for regular triage of candidate work. Needs usually filter down through performance analysis and experimentation.

All actively tracked work is marked with the whiteboard "[fce-active]" (for now). Or look at the #Active Bug List on this page.

Major initiatives are listed on this page.

Owned Infrastructure (needs updating per 1298080) Dashboards

  • Update Orphaning: functional

This is the symbolication server (aka "Snappy Symbolication Server") used by platform developers and performance dashboards. It is not used for the analogous process on Socorro. This is currently slated to be replaced by the owner of symbols, peterbe. See Tecken.

Historical knowledge areas

  • back-end of the user interface/XUL, et al (enn)
  • e10s system add-ons & system add-ons for feature rollout (felipe)
  • e10s data analysis (chutten)
  • install and update (rstrong, mhowell)
  • telemetry, histograms, pings, and data reporting (chutten)
  • stack-walking, breakpad, and crash pings (gsvelto, ccorcoran)
  • flash plugin-related (bytesized, felipe, dthayer)


Get More Data Faster

We need to reduce known blind spots and barriers to getting data AND commit to non-ADI based metrics. For this, our goals are to:

  • enable client-side stackwalking and send basic stack traces with crash pings (beginning in Nightly/Aurora, see 1280484)
  • enable content process crash reports (1293656)
  • differentiate between process types in crash pings (1310664)
  • process stack data in crash pings into a queryable result (1310695)
  • create pingSender to handle crash pings instead of Gecko (1310703)
  • enable client-side stackwalking and send basic stack traces with crash pings on all channels

See the roadmap here.

Set Flash to CTA by default

This includes:

  • prefer fallback content to Flash (1277346)
  • establish allowedlists and deniedlists (1307604, 1307605)
  • use heuristics to control when Flash is set to Click To Activate (1307606)
  • geography-specific SHIELD study in FF53 release to understand user response and impact (1335232)

See the details here.

App Updater and Installers

Update Orphan remediation

Remediation efforts have been tested for both system add-on capable and non (44.x and 43.0.1, respectively). Efforts are identified by ongoing analysis, including the update orphaning dashboard. This has yielded such things as:

  • continue the download instead of starting over after other networking errors occur (1309124)
  • create an Update Agent, responsible for running independently, daily, and downloading an update if found (1343669)
  • continue the download instead of starting over after NS_ERROR_DOCUMENT_NOT_CACHED occurs (1272585) (FF49)
  • download the update MAR file unthrottled (already landed) (1309125, 1309668)
  • serve a partial MAR file to Firefox 43.0.1 clients (1309130)
  • push either a system or hotfix add-on that changed the download throttle preference to 0 for FF 50+
  • run another method (non sysaddon, non SHIELD?, etc) to urge 43.0.1 users to upgrade
  • Updater UI is outdated, too big, and needs to be updated (893505) (FF55)
  • change compression to LZMA for updates (641212) (FF56)
  • move to SHA-384 for MAR signing (1324498) (FF56)

Installer UI

  • Streamlined installer testing in QX onboarding funnelcake (1328445)

Windows 64

We want to start moving users to 64-bit when appropriate:

  • stub installer should automatically select 32-bit or 64-bit (797208)

Current projects

2017 Q3 goals

  • APP UPDATE (see roadmap):
    • improve update security and performance via LZMA for MAR file compression and SHA384 certificates for MAR file signing
    • Increase visibility for update telemetry
    • Allow update download to continue in the background (beyond Firefox session)
  • INSTALLER (see roadmap):
    • Support onboarding
  • CRASH MACHINERY (see roadmap):
    • Optimize crash data that we send
    • Implement crash ping signatures
    • Start querying stacks received from crash pings for stability monitoring
    • Assist with measuring (and identifying) jank and hang via BHR
    • Assist with Quantum Flow and Photon Performance efforts for FF57 and FF58

Potential future projects

This list should be considered a work in progress. Decisions will be reflected for a particular quarter.

  • cmore is pitching that Firefox optimizes the user paths that support retention -- which could also include fixing paths where retention drops. This work probably involves a system add-on that initiates event-based recordation, as well as the analysis and remediation of the root cause (this is pending dcamp approval).
  • Firefox needs a "policy engine" (with API) to facilitate enterprise admins using Group Policies to ease deployment of Firefox in enterprise settings.
  • Update (rstrong) needs help with -- ideally for FF58.
  • DLL injection (see needs investigation/implementation of a dynamically updateable DLL blocklist (possibly using Kinto?).
  • On a personal note, if anyone experiences sluggishness in FF (on any channel) when you don’t restart it for a few days (maybe with several tabs open?), especially on Windows, please let me know (1398652).
  • Mossop (& browser arch) has begun the de-XBL. Overall browser architecture (& UI architecture) could be game in the near future.

(partial) Active Bug List

ID Product Summary Priority Status Whiteboard Keywords Assigned to
798847 Firefox "Time Remaining" missing while downloading P3 NEW [stubv3-][fce-active] uiwanted
799861 Firefox Stub installer does not detect proxy (Win7) P3 NEW [stubv3-][fce-active]
998721 Release Engineering Consider serving updates for 3.x and lower as minor updates to avoid displaying the billboard. P3 NEW [kanban:engops:] [fce-active] Nick Thomas [:nthomas] (UTC+13)
1256952 Core [e10s] Caret breaks in contenteditable elements when I drag anything over them (without dropping) P2 REOPENED [fce-active] Neil Deakin
1258895 Core Make test_bug426082.html and test_bug656379-1.html work with e10s -- NEW btpp-active [fce-active]
1280469 Firefox [meta] Client-side stack walking P2 NEW [fce-active] meta Gabriele Svelto [:gsvelto]
1282776 Core Some plugin-process crashes are not marked as plugin crashes (submitted-from-infobar related?) P2 REOPENED [fce-active] qawanted Gabriele Svelto [:gsvelto]
1296274 Toolkit Evalute symbolicating stack traces when doing client-side stack walking -- NEW [fce-active]
1301572 Toolkit Stop update staging when there is a shutdown request P2 NEW [fce-active]
1307153 Toolkit Add support for gathering client-side stack traces to Fennec -- NEW [fce-active]
1310674 Core [meta] Get more data faster. P2 NEW [fce-active] meta
1310680 Mozilla Metrics Update all usage of datasets that rely on crash ping aggregation -- NEW [fce-active]
1316366 Toolkit include information from update-settings.ini in update ping? -- NEW [fce-active]
1323979 Firefox Re-engineer the crash handling code to make the crash dump lifecycle robust -- ASSIGNED [fce-active] Gabriele Svelto [:gsvelto]
1324801 Toolkit Telemetry should throttle pings to a sane limit per day P3 NEW [measurement:client][fce-active]
1325121 Firefox Properly document stub installer ping P3 NEW [fce-active]
1330462 Firefox Using a different search engine to search for the same thing one just searched for is painful P3 NEW [fxsearch][fce-active] Doug Thayer [:dthayer]
1336587 Data Platform and Tools Signatures for crash pings P2 ASSIGNED [fce-active] Adam Gashlin [:agashlin]
1348273 Toolkit Make AnnotateCrashReport() more robust by turning annotations into a well known list of constants -- ASSIGNED [fce-active] Gabriele Svelto [:gsvelto]
1351509 Toolkit Reorganise information on the Flash plugin preferences page -- NEW [fce-active], triaged Bram Pitoyo [:bram]

20 Total; 20 Open (100%); 0 Resolved (0%); 0 Verified (0%);