Firefox Core Engineering

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Quoting the Platform/UI Team:

"The Platform teams and Firefox teams are co-dependent, but oftentimes priorities between the two groups do not line up perfectly. If Platform has a goal to ship some new feature that requires UI, and the Firefox team has no cycles to help develop the UX or UI, then it that feature will often languish."

This can happen in the opposite direction too, with Toolkit needing support for a feature that doesn't line up with current Platform priorities.

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 Platform through Toolkit, Data, and more.

This team grew out of, in part, the Performance Engineering team, and owns that team's previous infrastructure – performance-related dashboards on, the symbolication server, and more. It also includes the installer & updater applications.


  • Neil Deakin (:enn)
  • Adam Gashlin (:agashlin)
  • Felipe Gomes (:felipe)
  • Matt Howell (:mhowell)
  • Chris HC (:chutten)
  • 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 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 ripe for population.


You can typically find us in:


  • #fce
  • #developers
  • #e10s
  • #fx-team
  • #perf
  • #telemetry
  • #uptime

Mailing lists

  • bsmedberg-team
  • dev-platform
  • fhr-dev

Process and Queuing

There is currently no regimented process for regular triage of candidate work. Needs usually filter down through Benjamin Smedberg's team or tangentially related to 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

All of these dashboards are in the process of transferring ownership. Please contact ddurst if you need data that is currently not functional.

  • Add-on startup correlation: via iacomus; broken on 403 for S3 bucket
  • Add-on shutdown correlation: via iacomus; broken on 403 for S3 bucket
  • Main Thread I/O: via iacomus; broken on 403 for S3 bucket
  • Population Distribution: functional
  • Power Dashboard: functional
  • SlowSQL: functional
  • ChromeHangs: jquery csv issue resolved, backfilled data from 3/07 to 6/05
  • Update Orphaning: functional
  • Stability Dashboard: 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.

Historical knowledge areas

  • back-end of the user interface/XUL, et al (enn)
  • e10s system add-on (felipe)
  • e10s data analysis (chutten)
  • install and update (rstrong, mhowell)
  • telemetry, histograms, pings, and data reporting (chutten)
  • stack-walking and breakpad (gsvelto)
  • we keep moving him around (bytesized)


Current efforts

Get More Data Faster

We need to reduce known blind spots and barriers to getting data. 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 CrashSender to handle crash pings instead of Gecko (1310703)
  • enable client-side stackwalking and send basic stack traces with crash pings on Beta/GA

See the roadmap here.

Stability Dashboard for Relman

Relman has been using and related graphs to understand stability by build and channel; this is fine, but it relies on ADI and crash-stats rather than telemetry, and this is known to be unreliable. For this, our goals are to:

  • create a dashboard like, but based on telemetry (1297146) Stability dashboard:
  • establish confidence levels based on kilousagehours by comparing telemetry-based stability data with ADI-based stability data (ON HOLD)

Stabilize symbolapi.m.o

The symbolication API service is used by platform developers for debugging. It may also be used as part of the processing step for stacks received via crash pings. But there have historically been issues with its performance (1244589). Stabilizing this means:

  • rewrite symbolapi.m.o, adding tests and fixing caching
  • load test rewrite to ensure it improves on current uptime and load handling (PENDING)
  • coordinate with Ops to set up regular deployment process and transfer ownership (ON HOLD)

Experiment with setting Flash to CTA by default

All major browsers are stopping support for Flash; Firefox will stop supporting all NPAPI plugins (except Flash) shortly. Because there can be extreme user impact in blocking all Flash, we want to understand and attempt to smooth the transition to a post-Flash world. 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)

We hope to do a geography-specific SHIELD study in release to understand user response and impact (1277346).

See the details here.

Dashboard (repairs and additions)

Dashboards. So many dashboards.

  • change Update Orphaning dashboard to use MainSummary instead of longitudinal dataset
  • Removing potentially unused dashboards from t.m.o (1324526)
  • Updating dashboards (1324528)

Updater and Orphan remediation

Remediation efforts have been tested for both system add-on capable and non (44.x and 43.0.1, respectively). Analysis thus far confirms the reach but not the effectiveness or rate of conversion that we'd hoped for. This means:

  • continue the download instead of starting over after NS_ERROR_DOCUMENT_NOT_CACHED occurs (already fixed in Firefox 49) (1272585)
  • continue the download instead of starting over after other networking errors occur (1309124)
  • 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)
  • change compression to LZMA for updates (641212)
  • move to SHA-384 for MAR signing (1324498)
  • continue the download of an update if Firefox closes, instead of having to start over

Install 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 Q1 goals

  • update to v2
  • start querying stacks received from crash pings
  • relaunch of symbolapi.m.o (ON HOLD)
  • implement crash ping signatures
  • create "Plugin Safety" (Flash) SHIELD study
  • simplify Updater UI
  • LZMA and SHA384 for MAR files
  • land pingSender and implement for crashes and main pings

Potential future projects

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

  • Assisting with measuring (and addressing) jank and hang

(partial) Active Bug List

ID Product Summary Priority Status Whiteboard Keywords Assigned to
641212 Toolkit LZMA support for updater -- ASSIGNED [fxgrowth][fce-active] Matt Howell [:mhowell]
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]
1138399 Toolkit about:crashes doesn't list reports even if files exist under pending directory -- NEW [fce-active]
1246701 Cloud Services Prepare for log ingestion P3 NEW [SvcOps][fce-active]
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]
1274564 Toolkit Analysis of users with different hangs per minute and engagement ratio -- NEW [fce-active] Chris H-C :chutten
1280469 Firefox [meta] Client-side stack walking -- 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]
1286609 Cloud Services Add-on startup/shutdown dashboards error on accessing s3 file P3 NEW [fce-active] David Durst [:ddurst]
1296274 Toolkit Evalute symbolicating stack traces when doing client-side stack walking -- NEW [fce-active]
1301392 Core [e10s]slower startup when e10s is enabled with add-ons installed (or not) P2 NEW [bugday-20160912][mozfr-community][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. -- NEW [fce-active] meta
1310680 Mozilla Metrics Update all usage of datasets that rely on crash ping aggregation -- NEW [fce-active]
1310684 Cloud Services Verify validity of dataset changes after addition of new crash ping type P3 NEW [fce-active]
1310695 Cloud Services [meta] Process crash ping stacks to queryable result P3 NEW [fce-active]
1310699 Cloud Services Determine if reporting on (basic) stack data from crash pings should be via spark jobs or dedicated dataset P3 NEW [fce-active]
1310700 Cloud Services Determine method of symbolication of basic stacks in crash pings P3 NEW [fce-active]
1316007 Webtools Visualize histogram time-series as heatmap in evolution view of t.m.o -- NEW [fce-active]
1316366 Toolkit include information from update-settings.ini in update ping? -- NEW [fce-active]
1319071 Toolkit CrashManager.pendingDumps() does not recognize Linux minidumps correctly -- ASSIGNED [fce-active] Gabriele Svelto [:gsvelto]
1323979 Firefox Re-engineer the crash handling code to make the crash dump lifecycle robust -- NEW [fce-active]
1324528 Cloud Services Revise "Other dashboards" dashboards linked/shown on telemetry.m.o P2 NEW [fce-active]
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]
1331005 Cloud Services get_pings_properties doesn't work for filtering GPU process histograms P1 NEW [fce-active] George Wright (:gw280) (needinfo me!)
1331736 Firefox Alt+down in location bar searches for original search term rather than selected search term P3 NEW [fce-active][fxsearch] Doug Thayer [:dthayer]
1333128 Firefox Make the pingsender compress the outgoing ping with gzip -- NEW [fce-active]
1336587 Cloud Services Signatures for crash pings P2 ASSIGNED [fce-active] Adam Gashlin [:agashlin]

34 Total; 34 Open (100%); 0 Resolved (0%); 0 Verified (0%);