860196 - Mega.co.nz download stresses … everything

Status: RESOLVED INCOMPLETE

(Core :: JavaScript Engine, defect)

Description

[John Drinkwater (:beta)]

User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:22.0) Gecko/20130409 Firefox/22.0
Build ID: 20130409004013

Steps to reproduce:

Visited this download URL https://mega.co.nz/#!lJ4U1SiS!QUjb7EUuICwXi_G0io8J3yPRF0NjnGEKdlcyEI9apCo
( It’s a 2.2GB Battlefield 4 video from http://www.eurogamer.net/articles/digitalfoundry-watch-bf4-at-60fps )


Actual results:

Causes significant jank while its running in the background, as well as heavy memory usage.

At 18% of download complete, about:memory looks like:
1,033.24 MB (100.0%) -- explicit
├────857.31 MB (82.97%) -- window-objects
│    ├──842.43 MB (81.53%) -- top(https://mega.co.nz/#!lJ4U1SiS!QUjb7EUuICwXi_G0io8J3yPRF0NjnGEKdlcyEI9apCo, id=8)
│    │  ├──837.72 MB (81.08%) -- active/window(https://mega.co.nz/#!lJ4U1SiS!QUjb7EUuICwXi_G0io8J3yPRF0NjnGEKdlcyEI9apCo)
│    │  │  ├──833.32 MB (80.65%) -- js-compartment(https://mega.co.nz/#!lJ4U1SiS!QUjb7EUuICwXi_G0io8J3yPRF0NjnGEKdlcyEI9apCo)
│    │  │  │  ├──824.93 MB (79.84%) -- objects-extra
│    │  │  │  │  ├──824.16 MB (79.76%) ── elements/non-asm.js
│    │  │  │  │  └────0.77 MB (00.07%) ── slots
│    │  │  │  └────8.40 MB (00.81%) -- (6 tiny)
│    │  │  │       ├──5.28 MB (00.51%) ++ gc-heap
│    │  │  │       ├──1.61 MB (00.16%) ++ type-inference
│    │  │  │       ├──1.10 MB (00.11%) ++ shapes-extra
│    │  │  │       ├──0.37 MB (00.04%) ── script-data
│    │  │  │       ├──0.03 MB (00.00%) ── regexp-compartment
│    │  │  │       └──0.01 MB (00.00%) ── other-sundries
│    │  │  └────4.39 MB (00.42%) -- (4 tiny)
│    │  │       ├──2.13 MB (00.21%) ── style-sheets
│    │  │       ├──1.35 MB (00.13%) ++ layout
│    │  │       ├──0.90 MB (00.09%) ++ dom
│    │  │       └──0.01 MB (00.00%) ── property-tables
│    │  └────4.71 MB (00.46%) -- (2 tiny)
│    │       ├──3.92 MB (00.38%) ++ js-zone(7f0b6c4ee800)
│    │       └──0.80 MB (00.08%) ++ cached/window(about:home)
│    └───14.88 MB (01.44%) ++ (6 tiny)
├─────68.24 MB (06.60%) -- workers
│     ├──64.67 MB (06.26%) -- workers(mega.co.nz)
│     │  ├──16.66 MB (01.61%) -- worker(decrypter.js, 0x7f0b54b21800)
│     │  │  ├──13.97 MB (01.35%) -- zone(7f0b5655e800)
│     │  │  │  ├──13.69 MB (01.32%) -- compartment(web-worker)
│     │  │  │  │  ├──12.08 MB (01.17%) -- gc-heap
│     │  │  │  │  │  ├──12.03 MB (01.16%) -- objects
│     │  │  │  │  │  │  ├──12.00 MB (01.16%) ── dense-array
│     │  │  │  │  │  │  └───0.02 MB (00.00%) ── function
│     │  │  │  │  │  └───0.05 MB (00.00%) ++ (2 tiny)
│     │  │  │  │  └───1.61 MB (00.16%) ++ (8 tiny)
│     │  │  │  └───0.28 MB (00.03%) ++ (3 tiny)
│     │  │  └───2.69 MB (00.26%) ++ (4 tiny)
│     │  ├──16.66 MB (01.61%) -- worker(decrypter.js, 0x7f0b52039000)
│     │  │  ├──13.97 MB (01.35%) -- zone(7f0b555ab000)
│     │  │  │  ├──13.69 MB (01.32%) -- compartment(web-worker)
│     │  │  │  │  ├──12.08 MB (01.17%) -- gc-heap
│     │  │  │  │  │  ├──12.03 MB (01.16%) -- objects
│     │  │  │  │  │  │  ├──12.00 MB (01.16%) ── dense-array
│     │  │  │  │  │  │  └───0.02 MB (00.00%) ── function
│     │  │  │  │  │  └───0.05 MB (00.00%) ++ (2 tiny)
│     │  │  │  │  └───1.61 MB (00.16%) ++ (8 tiny)
│     │  │  │  └───0.28 MB (00.03%) ++ (3 tiny)
│     │  │  └───2.69 MB (00.26%) ++ (4 tiny)
│     │  ├──16.66 MB (01.61%) -- worker(decrypter.js, 0x7f0b532b7000)
│     │  │  ├──13.97 MB (01.35%) -- zone(7f0b5321d000)
│     │  │  │  ├──13.69 MB (01.32%) -- compartment(web-worker)
│     │  │  │  │  ├──12.08 MB (01.17%) -- gc-heap
│     │  │  │  │  │  ├──12.03 MB (01.16%) -- objects
│     │  │  │  │  │  │  ├──12.00 MB (01.16%) ── dense-array
│     │  │  │  │  │  │  └───0.02 MB (00.00%) ── function
│     │  │  │  │  │  └───0.05 MB (00.00%) ++ (2 tiny)
│     │  │  │  │  └───1.61 MB (00.16%) ++ (8 tiny)
│     │  │  │  └───0.28 MB (00.03%) ++ (3 tiny)
│     │  │  └───2.69 MB (00.26%) ++ (4 tiny)
│     │  └──14.70 MB (01.42%) -- worker(decrypter.js, 0x7f0b598b0000)
│     │     ├──13.48 MB (01.30%) -- gc-heap
│     │     │  ├──12.00 MB (01.16%) ── unused-chunks
│     │     │  └───1.48 MB (00.14%) ++ (2 tiny)
│     │     └───1.22 MB (00.12%) ++ (4 tiny)
│     └───3.57 MB (00.35%) -- workers()
│         ├──1.79 MB (00.17%) ++ worker(resource://gre/modules/osfile/osfile_async_worker.js, 0x7f0b749eb800)
│         └──1.78 MB (00.17%) ++ worker(resource://gre/modules/PageThumbsWorker.js, 0x7f0b6bdde800)
├─────48.09 MB (04.65%) ── heap-unclassified
├─────40.00 MB (03.87%) -- js-non-window
│     ├──23.67 MB (02.29%) -- zones
│     │  ├──19.79 MB (01.92%) ++ zone(7f0b7a137000)
│     │  └───3.88 MB (00.38%) ++ (2 tiny)
│     ├──10.95 MB (01.06%) ++ runtime
│     └───5.38 MB (00.52%) ++ gc-heap
├─────10.62 MB (01.03%) ++ storage
└──────8.97 MB (00.87%) ++ (16 tiny)


Expected results:

A smooth ‘download’. Bug 832732 may mitigate this problem, but some of the problems here could be this:
│    │  │  │  ├──824.93 MB (79.84%) -- objects-extra
│    │  │  │  │  ├──824.16 MB (79.76%) ── elements/non-asm.js