D1 garbage collector + threads + malloc = garbage?

[Walter Bright]

Sean Kelly wrote:
> Leandro Lucarella Wrote:
> 
>> Bane, el 11 de diciembre a las 06:00 me escribiste:
>>> Bug with GC fullCollect() in multithreaded environment. Grauzone
>>> explained it here
>>> http://www.digitalmars.com/webnews/newsgroups.php?art_group=digitalmars.D&article_id=99610
>>> 
> 
> To be perfectly safe, it's a tiny bit trickier than that.  You have
> to always lock on allocations instead of just locking the collection
> cycle in single-threaded apps.  I think the reason for this is that
> once the lock is acquired it must be held until the current thread
> exits the GC code, and the "synchronized" statement only allows you
> to lock for the length of the collect() call (because the start and
> end must be within the same scope).  However, this /may/ actually be
> a separate bug with the D 1.0 GC.  I really can't recall for sure if
> this was an issue with collecting when all the other threads were
> suspended.

Yes, the lock on the gc must still be held until the collection work is 
completed, but the other threads can be unfrozen once the mark phase is 
complete.