[Webkit-unassigned] [Bug 92198] Web Inspector: [JSC] debugging long-running scripts with conditional breakpoints consumes huge amounts of memory

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=92198





--- Comment #7 from Peter Wang <peter.wang at torchmobile.com.cn>  2012-12-13 18:55:24 PST ---
(In reply to comment #6)
> (In reply to comment #2)
> > This problem is more obvious in memory-limited environment (e.g. mobile).
> > 
> > The root reason is that, for failed condition of breakpoint, JSC doesn't run the EventLoop, so in a dense loop of js code, there is no chance to recycle garbage caused by evaluating the breakpoint's condition.
> > 
> It sounds weird that the issue is specific to breakpoint conditions. How does it work in case of eval producing a lot of garbage in a tight loop in user code?
> 
Sorry to reply so late, since I spent some time to investigate the related code of JSC. For the code like this:
for (var i=0;i<0xfffff;i++) {
...
eval("...");
...
}
The "EvalExecutable" is allocated just once and saved as an argument of current callFrame (Interpreter.cpp:149).

But to evaluate the condition of breakpoint, the DebuggerCallFrame::evaluate is invoked, the "EvalExecutable" is allocated every time. Maybe, because it's difficult to bind the breakpoint-condition's string with a certain callFrame.

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