Re: True faiths ( was Re: The true faith )

[Jim Rogers <jimmaureenrogers@worldnet.att.net>]

Larry Kilgallen wrote:

> In article <3C4DFA24.4020107@worldnet.att.net>, Jim Rogers <jimmaureenrogers@worldnet.att.net> writes:
> 
> 
>>Aha. There are solutions to this problem, with or without GC.
>>The solution is to provide a separate storage pool for each
>>thread. That storage pool could then be managed manually or by
>>GC. With this design, one thread consuming its storage pool would
>>not interfere with the storage usage of other threads.
>>
> 
> What happens when one thread passes an object to another thread ?
> 


You have three choices. 

1) Only objects allocated from a global storage pool can be passed
    between threads.
2) (Yuck) Objects are only passed by copy, not by reference.
3) Any object can be passed by reference. Objects from a local
    storage pool cannot be allocated by any but their local thread.
    This option really makes deallocation, either manual or GC, very
    hard to get right. :-(

The first option is often enforced by multi-processor systems,
where shared data must be in a special region of memory visible
to all processors. In Ada terms, this region of memory would be
used only for protected objects.

Of course, with this option, it is still possible for a single
thread to unfairly dominate memory usage. As in all cases, you
stil need to design intelligently to limit storage pool
contention.

Jim Rogers
Colorado Springs, Colorado USA