On Tue, Apr 13, 2010 at 2:12 PM, Reko Tiira <[email protected]> wrote:
> I want to embed V8 in my game engine, mainly because I prefer it's C++
> API over that of SpiderMonkey's.
Amen, Reko!
> {
> v8::Unlocker ul;
> Sleep(2);
> }
>
Be aware that you must have a Locker in place before you do that, or the
Unlocker will crash/assert. My case was very similar to yours, but since my
code which uses Unlocker is plugin code (which might or might not be loaded
by any given client), i had to go back and hack each client application to
add a Locker before creating the context.
> // For sake of not having to write almost two identical functions,
> // assume that ONLY thread 1 does this:
> {
> v8::Unlocker ul;
> Sleep(2);
> }
> std::string s = String::AsciiValue ascii(str);
>
i might be mis-understanding the context here, but make sure that you do not
use any v8 resources (e.g. the String constructor) while you are unlocked.
> Let's say that two threads run this same script. When the first thread
> unlocks for the first time and goes to sleep, the 2nd thread will
> create a new HandleScope, and thus all consecutive allocations are
> done on the 2nd thread's handle scope.
Another tip: get rid of the HandleScopes. i've spent many hours
experimenting and they cause me nothing but grief. Mysterious segfaults when
a bound function returns? 9 times out of 10 it's caused by the mere
existence of a HandleScope. i don't use them at all any more, and i can't
see a functional difference (other than that my apps don't crash when the
bound functions return, unless i've done something else illegal).
> So when thread 2 goes to sleep,
> and thread 1 wakes up
will GET A CHANCE to wake up. Other threads might contend.
> , it'll create a new String using the HandleScope
> that was created on the thread 2 while thread 1 was sleeping. Now
> thread 1 will go to sleep again, and thread 2 will wake up. At this
> point thread 2 simply returns, and since the HandleScope goes out of
> scope, it'll free all the locals that it had allocated, _including_
> the string created in thread 1 (since it was allocated using the wrong
> HandleScope). After this the control returns back to the thread 1,
> which tries to use the already de-allocated value, and probably crash
> because of that.
>
That sounds right to me (i say, without having actually run the code).
Am I getting this right? If I am, is there any plausible way to get
> around this, because I really need to be able to run multiple scripts
> at the same time, but I have plenty of scripts that would block until
> some sort of an event happens in the game, and other scripts need to
> be able to run during the time the script waits.
>
To me it looks like you're on the right track, but:
- IMO you should not try to use a var created from Thread A over in Thread B
- that just "sounds dangerous" to me. Maybe v8 does allow this, though.
- My opinions are limited to my experience and the meager docs on the topic.
Happy hacking!
--
----- stephan beal
http://wanderinghorse.net/home/stephan/
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