bug at remove() ?

ig0r · Post by **ig0r** » Fri Dec 17, 2004 9:34 pm

hi
if i shot at my scenenode with a gun , the nodes lost health points...
at healthpoints ==0 i try to remove them but if i

node->remove()
i get sometimes a crash at ->drawAll()

but if i do a
node->setVisible(false);
i get no crash , but this is a stupid solution.....

have anybody else this problem ....

Morrog · Post by **Morrog** » Fri Dec 17, 2004 9:58 pm

I've removed gobs of node without a problem. I think you have a bug elsewhere.

ig0r · Post by **ig0r** » Sat Dec 18, 2004 9:45 am

i cannnot belive, because everything works fine if i set them invisible, but if i do a remove() i get a crash at 0xfeefeeee in drawALL()

is it not possible to remove more nodes at once ???

ig0r · Post by **ig0r** » Sat Dec 18, 2004 12:17 pm

me i think i have fixed the bug now, but i don't know the reason why there was a bug

let me explain.

[thread 1 ]
remove() a scenenode
and
drawAll()

[thread2]
remove() another sceennode

-----
if thread1 removes the node i catch an execption at drawall

but if i set up a mutex on the 2 removes() and the one drawall()

there is no bug at all... but why not ??

is it possible that the 2 threads run through remove() at the same time ??

best regards

killer7 · Post by **killer7** » Sat Dec 18, 2004 3:08 pm

thats impossable, threads mearly sub-devide time, only one thread is actully running at a time.

They just switch back and forth between threads so quickly you cant see the difference .

bal · Post by **bal** » Sat Dec 18, 2004 3:10 pm

sgmr->addToDeletionQueue(node);

?

Spintz · Post by **Spintz** » Sat Dec 18, 2004 6:53 pm

killer7 wrote:thats impossable, threads mearly sub-devide time, only one thread is actully running at a time.

They just switch back and forth between threads so quickly you cant see the difference .

Sort of, acutally, it is quite possible for threads to step on each other. The OS level of threading is very complex, but basically, one thread may start a remove, and then the OS gives another thread some time and it then also does a remove. If it was impossible for threads to step on each other, there would be no need for mutexes.

Anyways, that was definitely your problem. If you have multiple threads which do anything to the same data then you need to have a mutex to protect that data.