top(none)/detached/window(chrome://browser/content/browser.xul)/dom/event-listeners lingers until restart

[Fanolian]

The test is done with about:memory in Nightly and TST nightly version (currently 0.15.2015031900a181223)

Steps to reproduce:

1. In a new profile, install TST in Nightly. Leave all settings as default
2. Open one tab and only in one window. Go to about:memory.
3. Minimize memory usage a few times then measure. The result at Main Process - Other Measurements - event-counts should be similar to :

1,551 (100.0%) -- event-counts
└──1,551 (100.0%) -- window-objects
   ├──1,299 (83.75%) -- top(chrome://browser/content/browser.xul, id=3)/active
   │  ├──1,298 (83.69%) -- window(chrome://browser/content/browser.xul)/dom
   │  │  ├──1,295 (83.49%) ── event-listeners
   │  │  └──────3 (00.19%) ── event-targets
   │  └──────1 (00.06%) ── window(about:blank)/dom/event-targets
   ├────214 (13.80%) -- top(about:newtab, id=17)/active/window(about:newtab)/dom
   │    ├──212 (13.67%) ── event-listeners
   │    └────2 (00.13%) ── event-targets
   ├─────21 (01.35%) ++ (4 tiny)
   └─────17 (01.10%) ++ top(about:memory, id=9)/active/window(about:memory)/dom

4. Open a new window or a new private window, then close it.
5. Minimize memory usage and measure again. a top(none)/detached/window(chrome://browser/content/browser.xul)/dom/event-listeners is created.
6. Repeat step 4 and 5 a few times. More top(none)/detached/… are created and cannot be destroyed unless restarting Nightly. This may end up like:

9,982 (100.0%) -- event-counts
└──9,982 (100.0%) -- window-objects
   ├──8,632 (86.48%) ── top(none)/detached/window(chrome://browser/content/browser.xul)/dom/event-listeners [12]
   ├──1,299 (13.01%) -- top(chrome://browser/content/browser.xul, id=3)/active
   │  ├──1,298 (13.00%) -- window(chrome://browser/content/browser.xul)/dom
   │  │  ├──1,295 (12.97%) ── event-listeners
   │  │  └──────3 (00.03%) ── event-targets
   │  └──────1 (00.01%) ── window(about:blank)/dom/event-targets
   └─────51 (00.51%) ++ (6 tiny)

Without TST, top(none)/detached/… is gone after minimizing memory usage.

I don't know if this issue impacts TST's functions or Firefox's performance (as I know nothing about coding), but this is definitely something abnormal.

[Fanolian]

Is it the same or similar to Bug 1142597 - sdk/tabs memory leak when opening and closing new windows?

[jryans]

Is it the same or similar to Bug 1142597 - sdk/tabs memory leak when opening and closing new windows?

I don't think it's this bug because TST does not make use of the SDK. But, it could be something similar.

[Fanolian]

I don't know if commit 94428a1 is related, but I can still reproduce the issue on TST nightly 0.15.2015061300a003855

[piroor]

Confirmed on Nightly 45.0a1 with TST 9f14f59. But currently I have not enough time to research the reason why TST grabs the memory...

[Fanolian]

This was fixed in 0.16.2015111001 already. Thanks!
Commit range: 9516999...000ce6b (only some are relevant)