Performance/MemShrink
MemShrink is a project that aims to reduce the memory consumption of Firefox (on desktop and mobile). There are three potential benefits.
- Speed. Firefox will be faster due to less cache pressure, less paging, and fewer/smaller GC and CC pauses. Changes that reduce memory consumption but make Firefox slower are not desirable.
- Stability. Firefox will suffer fewer aborts/crashes due to virtual or physical memory exhaustion. The former is mostly a problem on 32-bit Windows builds with a 2GB or 4GB virtual memory limit, the latter is mostly a problem on mobile devices that lack swap space.
- Reputation. Fewer people will complain that Firefox is a memory hog and that Mozilla ignores memory usage.
This blog post describes these benefits in more detail.
There are two main ways to reduce memory consumption.
- "Slim down" memory usage, e.g. make data structures more space-efficient.
- Avoid "leaks". This loose use of the term (which is used throughout this document) includes:
- True leaks, where memory is lost forever.
- Lifetime issues, where memory is not reclaimed until you close the page/tab/window/process.
- Collection heuristic issues (e.g. GC is too infrequent).
- Bad cache algorithms and poorly tuned caches.
- Fragmentation.
Leaks are generally more important, because they are more likely to lead to horrible performance.
Meetings
Meetings happen every second Wednesday at 11am Pacific time (countdown in your timezone)
- Dial-in: Audio-only conference# 95346
- People with Mozilla phones or softphones please dial x4000 Conf# 95346
- US/Toll-free: +1 800 707 2533, (pin 4000) Conf# 95346
- US/California/Mountain View: +1 650 903 0800, x4000 Conf# 95346
- US/California/San Francisco: +1 415 762 5700, x4000 Conf# 95346
- US/Oregon/Portland: +1 971 544 8000, x4000 Conf# 95346
- CA/British Columbia/Vancouver: +1 778 785 1540, x4000 Conf# 95346
- CA/Ontario/Toronto: +1 416 848 3114, x4000 Conf# 95346
- UK/London: +44 (0)207 855 3000, x4000 Conf# 95346
- FR/Paris: +33 1 84 88 37 37, x4000 Conf# 95346
- Gmail Chat (requires Flash and the Google Talk plugin): paste +1 650 903 0800 into the Gmail Chat box that doesn't look like it accepts phone numbers
- SkypeOut is free if you use the 800 number
- zoom: 310 455 675
- IRC: #memshrink
Bug Tracking
Bugs are prioritized during MemShrink meetings.
If you want a bug that is related to memory usage to be triaged in a MemShrink meeting, add "[MemShrink]" to the bug whiteboard. After prioritization, this whiteboard marking will be changed to one of "[MemShrink:P1]", "[MemShrink:P2]", "[MemShrink:P3]" or "[MemShrink:meta]". The meaning of these markings, and links to all such bugs, is as follows.
- Unprioritized MemShrink bugs. These are prioritized regularly in meetings.
- MemShrink:P1 bugs. Once prioritized, these will be revisited and discussed occasionally in meetings.
- MemShrink:P2 bugs. Once prioritized, these will be revisited and discussed rarely in meetings. P2 is the default priority.
- MemShrink:P3 bugs. Once prioritized, these are unlikely to be revisited and discussed again in meetings.
- MemShrink:meta bugs. Once prioritized, these will be revisited and discussed occasionally in meetings.
Some other interesting bug lists that overlap with the ones above.
- All MemShrink bugs.
- Unconfirmed MemShrink bugs. These are problems reported by users and generally require some kind of additional work to confirm.
- MemShrink bugs with a "mentor" annotation. These are bugs that someone has identified as reasonable easy, and that person is willing to help a newcomer fix the bug.
- Unassigned MemShrink bugs. These need someone to work on them.
Tools
All the tools that we use to measure and improve memory usage are described on MDN, under "Memory profiling and leak detection tools".
Meeting Minutes, Progress Reports and Presentations
We no longer take meeting minutes nor make progress reports, but the meetings still happen. Brief MemShrink updates are given in the minutes of the weekly Platform meeting (wiki, blog). And nnethercote still blogs about major MemShrink occurrences.
Here is the historical record from when we did take minutes and make progress reports.
| Date | Minutes | Progress report |
|---|---|---|
| 2014-06-16 | - | MemShrink's 3rd Birthday (includes the fourth "Big Ticket Items" list) |
| 2013-11-26 | - | The final progress report |
| 2013-10-29 | - | Week 121--124 |
| 2013-09-30 | - | Week 117--120 |
| 2013-09-03 | - | Week 113--116 |
| 2013-08-06 | - | Week 109--112 |
| 2013-07-09 | - | Week 105--108 |
| 2013-06-14 | - | MemShrink's 2nd Birthday (includes the third "Big Ticket Items" list) |
| 2013-06-11 | - | Week 103--104 |
| 2013-05-28 | - | Week 99--102 (guest post) |
| 2013-04-30 | - | Week 97--98 (guest post) |
| 2013-04-16 | - | Week 95--96 |
| 2013-04-02 | - | Week 93--94 |
| 2013-03-19 | - | Week 91--92 |
| 2013-03-05 | - | Week 89--90 |
| 2013-02-19 | - | Week 87--88 |
| 2013-02-05 | - | Week 85--86 |
| 2013-01-22 | - | Week 83--84 |
| 2013-01-08 | - | Week 79--82 |
| 2012-12-11 | - | Week 77--78 |
| 2012-11-27 | - | Week 75--76 |
| 2012-11-13 | - | Week 73--74 |
| 2012-10-30 | - | Week 71--72 |
| 2012-10-16 | - | Week 69--70 |
| 2012-10-02 | - | Week 67--68 |
| 2012-09-18 | - | Week 65--66 |
| 2012-09-04 | - | Week 63--64 |
| 2012-08-21 | - | Week 61--62 |
| 2012-08-07 | - | Week 57--60 |
| 2012-07-10 | - | Week 55--56 (includes the second "Big Ticket Items" list) |
| 2012-06-26 | - | Week 53--54 |
| 2012-06-14 | - | MemShrink's 1st Birthday |
| 2012-06-12 | - | Week 51--52 |
| 2012-05-29 | - | Week 49--50 |
| 2012-05-15 | - | Week 47--48 |
| 2012-05-01 | - | Week 45--46 |
| 2012-04-17 | - | Week 43--44 |
| 2012-04-03 | - | Week 42 |
| 2012-03-27 | - | Week 41 |
| 2012-03-20 | - | Week 40 |
| 2012-03-13 | - | Week 39 |
| 2012-03-06 | - | Week 38 |
| 2012-02-28 | - | Week 37 |
| 2012-02-21 | - | Week 36 |
| 2012-02-14 | - | Week 35 |
| 2012-02-07 | - | Week 34 |
| 2012-01-31 | - | Week 33 |
| 2012-01-24 | - | Week 32 (includes the first "Big Ticket Items" list) |
| 2012-01-17 | - | Week 31 |
| 2012-01-10 | - | Week 30 |
| 2012-01-03 | - | Weeks 28--29 |
| 2011-12-20 | - | Week 27 |
| 2011-12-13 | minutes | Week 26 |
| 2011-12-06 | minutes | Week 25 |
| 2011-11-29 | minutes | Week 24 |
| 2011-11-22 | - | Week 23 |
| 2011-11-15 | - | Week 22 |
| 2011-11-08 | minutes | Week 21 |
| 2011-11-01 | minutes | Week 20 |
| 2011-10-25 | minutes | Week 19 |
| 2011-10-18 | minutes | Weeks 13--18 |
| 2011-10-11 | minutes | - |
| 2011-10-04 | minutes | - |
| 2011-09-27 | - | - |
| 2011-09-20 | minutes | - |
| 2011-09-13 | - | - |
| 2011-09-06 | minutes | Week 12 |
| 2011-08-30 | minutes | Week 11 |
| 2011-08-23 | minutes | Week 10 |
| 2011-08-16 | minutes | Week 9 |
| 2011-08-09 | minutes | Week 8 |
| 2011-08-02 | - | Week 7 |
| 2011-07-26 | minutes | Week 6 |
| 2011-07-19 | minutes | Week 5 |
| 2011-07-12 | minutes | Week 4 |
| 2011-07-05 | minutes | Week 3 |
| 2011-06-28 | - | Week 2 |
| 2011-06-21 | - | Week 1 |
| 2011-06-14 | - | - |
Presentations.
- 2012-01-16 "Notes on Reducing Firefox's Memory Consumption", presented at linux.conf.au Browser MiniConf
