Comment #15 on issue 16821 by [email protected]: Memory leak
http://code.google.com/p/chromium/issues/detail?id=16821
So I think I know it all now.
There are two sources of global handles (after the 1st loop):
1) persistent handles for functions which where setTimeout'ed (see
DisplayAuto
function in leak.htm); the relevant parts of the code:
ScheduledAction* action = new
ScheduledAction(V8Proxy::context(imp->frame()),
v8::Handle<v8::Function>::Cast(function), paramCount, params);
(ln. 116 of V8DOMWindowCustom.cpp).
and
ScheduledAction::ScheduledAction(v8::Handle<v8::Context> context,
v8::Handle<v8::Function> func, int argc, v8::Handle<v8::Value> argv[])
: m_context(context)
, m_code(String(), KURL(), 0)
{
m_function = v8::Persistent<v8::Function>::New(func);
In this particular case we pass the same function, but create a new
persistent handle
for each page.
2) [and that's more important]: actually we crate a lots of new nodes due
to one
nasty thing: in Fetch div.firstChild HTML is updated. As WebKit doesn't
check if
HTML fragments are the same, it just reinitializes
div.firstChild.firstChild node.
So on each iteration another WebKit Node is created and none is released.
Just to check: either comment update of innerHTML or do not lookup second
firstChild
(that is: dummy = div.firstChild)---with those changes this leak.htm runs
ways longer
on my box even though it still leaks due to creation of global handles.
Now to how to fix it. We could adapt approach used in JSC and partially in
V8/DOM
bindings: associate an external cost (e.g. each global handle would include
roughly
the size of WebKit node it wraps), then this cost grows beyond some limit,
let's GC.
Another approach, notably easier and less intrusive, could be to check on
global
handle creation several things like total number of global handles, amount
of
allocated data in the heap, last gc time, etc. and force GC from time to
time.
My main concern would be performance implications.
Let me think one night and I would appreciate any other ideas/discussion.
And I'm
pointing out this bug to the rest of V8 team in hope get some cool ideas.
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