Hi Vyacheslav,
I guess you are right: additional context is not really needed there.
Let me
try to remove it and see if it improves GC.
I am not really using any weak reachable objects explicitly. I am not
sure though if they can be potentially be created in Javascript.
My test case produces GC-collectable string in the endless loop...
var task = require("task"),
x = 1;
for (var i = 0; i < 10 ; i++) {
var t = task.createTask(function() {
var r = "";
while (1) {
r = "BB " + x;
}
});
console.log("Task created " + i);
t.run();
}
Would it produce weak references? I think not, right?
Thanks,
Denis
On Sep 1, 12:47 pm, Vyacheslav Egorov <[email protected]> wrote:
> > 1. Can I transfer an function object from script compiled in global
> > context and main thread Isolate into the other thread's Isolate and
> > execute there?
>
> No. You have to serialize it somehow (e.g. JSON) in one isolate and
> deserialize it in another one.
>
> > 2. If not, Is what I am doing a valid v8 API usage at all? What could
> > be other ways to trigger GC more often?
>
> Seem valid to me. But I am a bit confused why forcing GC manually helps so
> much.
>
> It's not completely clear though why do you need a separate context
> for your task because the function you pass as value (not as source)
> already has a context attached and will use it but not the context you
> have created.
>
> Another thing: do you use weak handles extensively? V8 might be
> overflowed by weakly reachable objects. That might cost a lot
> especially if those weakly reachable objects hold onto contexts which
> you seem to allocate for each task.
>
> --
> Vyacheslav Egorov
>
> On Thu, Sep 1, 2011 at 8:34 PM, Dennis H <[email protected]> wrote:
> > Hi Vyacheslav,
>
> > I see your point.
>
> > I don't use separate Isolate for each thread and all tasks use
> > function objects compiled in the global Context/Isolate.
> > This might be a trouble of course, but I was not sure there is a good
> > way to create a function object
> > in main Context and then transfer it to another Isolate/Context.
>
> > Essentially I wanted to achieve following usage:
>
> > // thread function
> > function foo () {}
>
> > // starts execution in a separate thread
> > task(foo);
>
> > I do make them run exclusively (at least I hope I do) by using
>
> > Locker locker;
> > Locker::StartPreemption(preemption_interval);
> > HandleScope scope;
>
> > context = Context::New();
> > context->Enter();
>
> > The code is in a fork from nodejs.You can see the code here:
> >https://github.com/bfrancojr/node/blob/node-task/src/node_task.cc
>
> > The funny part is that if I create just a couple of threads the memory
> > is stable, while I call V8::IdleNotification() every 5 sec.
>
> > If I increase the number of tasks to 100 it will start to grow and
> > the process will run out memory. However If I start to call
> > V8::IdleNotification() every 0.3 seconds it fixes it again.
>
> > I've got a feeling the v8 treats the GC as one of the tasks, meaning
> > that the more tasks I create the more time is allocated to 'garbage
> > producers'
> > and the smaller is a relative portion of time for GC. May be I am
> > wrong.
>
> > So the questions are:
>
> > 1. Can I transfer an function object from script compiled in global
> > context and main thread Isolate into the other thread's Isolate and
> > execute there?
> > 2. If not, Is what I am doing a valid v8 API usage at all? What could
> > be other ways to trigger GC more often?
>
> > Thanks,
> > Dennis
>
> > On Aug 31, 12:44 am, Vyacheslav Egorov <[email protected]> wrote:
> >> Hi Dennis,
>
> >> V8's GC is stop-the-world type so you don't have to do anything
> >> special to make it "keep up". If you are getting OOM that most
> >> probably means you have a leak somewhere. Try tracing GC with
> >> --trace-gc flag to see how heap grows.
>
> >> Also you can't run JavaScript in parallel on V8 unless you create
> >> several isolates.
>
> >> If you are using a single isolate from many threads you have to ensure
> >> that only one thread is executing JS at the given moment.
>
> >> --
> >> Vyacheslav Egorov
>
> >> On Wed, Aug 31, 2011 at 2:28 AM, Dennis H <[email protected]> wrote:
> >> > Dear v8 Developers,
>
> >> > I am relatively new to v8 internals, but here is what I found:
> >> > I tried to create an app which has multiple tasks running in parallel.
> >> > The v8::internal::Thread API seems to work fine, the trouble is I
> >> > didn't find a good way to make garbage collection to keep up.
>
> >> > I do call the V8::IdleNotification() in the main event loop
> >> > periodically, but it doesn't scale if number of threads is getting
> >> > bigger. Essentially If I create a lot of tasks, the process would
> >> > reliably run out of memory pretty quick.
>
> >> > How is the garbage collection supposed to be handled correctly with
> >> > multiple threads?
>
> >> > I used v3.4.14.
>
> >> > Thanks,
> >> > Dennis
>
> >> > --
> >> > v8-users mailing list
> >> > [email protected]
> >> >http://groups.google.com/group/v8-users
>
> > --
> > v8-users mailing list
> > [email protected]
> >http://groups.google.com/group/v8-users
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