[tor-bugs] #15502 [Tor Browser]: URL.createObjectURL() considered harmful

[Tor Bug Tracker & Wiki]

#15502: URL.createObjectURL() considered harmful
-------------------------+-------------------------------------------------
     Reporter:           |      Owner:  arthuredelstein
  mikeperry              |     Status:  needs_review
         Type:  defect   |  Milestone:
     Priority:  major    |    Version:
    Component:  Tor      |   Keywords:  tbb-linkability, tbb-newnym,
  Browser                |  tbb-4.5-alpha, TorBrowserTeam201504R,
   Resolution:           |  MikePerry201504R
Actual Points:           |  Parent ID:
       Points:           |
-------------------------+-------------------------------------------------

Comment (by mikeperry):

 While testing the Torbutton piece, I noticed that about:memory was still
 reporting many page objects still present after New Identity. I couldn't
 manage to catch any blob: urls still alive in there, but it was enough to
 worry me.

 I reviewed the garbage collector source in Firefox and it was a complete
 nightmare due to many layers of timers, incremental GC and CC heuristics,
 and other performance hacks. It turns out even calling the
 garbageCollect() call like you did only schedules a GC call 4-10 seconds
 later, at best. We have to jump through all sorts of hoops to get the
 thing to run immediately. I think this commit finally does the trick:
 https://gitweb.torproject.org/mikeperry/torbutton.git/commit/?h=15502&id=1118c7914492a981147f34af26a4968ee8570bb9

 I tested this by setting my homepage to about:memory, so I could click the
 'Measure' button as fast as possible after New Identity.

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/15502#comment:16>
Tor Bug Tracker & Wiki <https://trac.torproject.org/>
The Tor Project: anonymity online