[plt-scheme] Using Scheme_Object * from another thread

Adam Wick schreef:

> No, I'm not sure.
>
> For one thing, I'm not that familiar with the base collector, and for
> another, I believe the one we use is at least slightly hacked. I'm not
> entirely sure what the invariants are. You're going to have to wait

???

> for Matthew's $0.02 on that one.

???
What's Matthew's $0.02?

Thanks,
Hans

>
>
> -Adam
>
> Hans Oesterholt-Dijkema wrote:
>
>>
>> I thought Hans Boehms GC was thread safe. Are you sure?
>>
>> Hans
>>
>>
>>
>> Adam Wick schreef:
>>
>>>
>>> You will see intermittent failures in the 3m variants. I don't know the
>>> non-3m code nearly as well, but I suspect you will see failures there,
>>> as well.
>>
>>
>>
>>
>>>
>>> In order to do this safely, you'd need to (a) completely block the 
>>> Scheme
>>> thread from allocating while your OS thread was running, (b) (most 
>>> likely)
>>> force a garbage collection immediately on starting the OS thread and 
>>> (c) make
>>> sure your OS thread isn't allocating enough memory such that it'll 
>>> trigger a
>>> collection after the collection in (b). I would suspect that 
>>> enforcing these
>>> would cost notably more than the savings you'll get from 
>>> multithreading.
>>>
>>>
>>>
>>> -Adam
>>>
>