Author: Robert Hyatt
Date: 10:39:20 11/17/04
Go up one level in this thread
On November 17, 2004 at 07:50:29, Daniel Shawul wrote:
>I have some programming difficulties on multi threaded search.
>
>One problem is that allocating memory in search is a problem
>
>search(alpha,beta,...)
>{
> SPLIT* p_split;
> p_split = new SPLIT;
>
> if(search in parallel)
> searchInparallel(...)
> else
> search()
>
> delete p_split; //here it crashes
>}
>
>The error message says "you can only delete memory from *local* heap".
>Do threads have their own heap memory?
Nope. Each thread does have it's own stack memory, although any thread can
see any other thread's stack if it tries hard enough since all memory is
shared among threads...
>When i change in to using a split object than using a pointer it works fine.
>but i am thinking this is slower than allocating memory when only i need to
>split search. what do you suggest?
Forget allocating memory. It is slow because it requires synchronization
between the threads since they share the same virtual address space. The
threads have to synchronize if two or more try to allocate something at the same
time. No dynamic allocation inside the engine.... too slow...
>
>Another question is do i need to lock/unlock common data for threads
>which is a read only type?
Nope. Only if it is modified.
>
>Do you block the main(parent) thread when search is split? i have read ('m not
>sure though) this may cause a problem but it seems to work fine for me.
I don't. that way I just have four threads at all times, never blocked threads
waiting on busy threads. That is a performance reducer... It is easier to use
your idea, but a little less efficient.
>
>thanks in advance
>daniel
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