To clarify... where is says "if finalization is robust enough, then it
will continue finalizing", it means "if [the] finalization [process that
kicks off finalization on individual weak arrays by draining the
finalization queue] is robust enough [so that the hang in w's
finalization doesn't bring down the whole thing], then it will continue
finalizing [other objects]".
On 12/27/11 3:47 , Andres Valloud wrote:
He might imply "any finalization process that runs on the weak
collection after the objects are collected must be thread safe", which
seems reasonable. You may get away with free "atomic" finalization if
you have a finalization queue... but not always. For example, what
happens if the finalization queue contains the weak array w (because the
GC nilled some of w's slots), then the image starts finalizing w but the
process has a DNU of some sort so it stops... if finalization is robust
enough, then it will continue finalizing. Then you get another GC, w
gets added to the finalization queue again because some other of its
slots got nilled, and then the finalization is kicked off on w *again*
while the first one is hung with the debugger open...
On 12/27/11 2:39 , Igor Stasenko wrote:
i cannot get it, how weak type containers are related to thread safety?
A garbage collection happens instantly for language side , so there is
no way how a weak collection can be in inconsistent state when
it is not known yet, if object is dead or alive.
By accessing an object in weak container, you put it's reference on
stack, which means that if GC will happen at that stage, a
corresponding object will not be
collected until at least next GC phase.
Now what is "thread-safe weak collections" and what they should serve for?
WeakIdentityKeyDictionary? It is not thread-safe. And why it should,
when you can easily make it thread-safe by wrapping it with
appropriate container object.
What else?
WeakArray? it is already thread safe: reads and writes are primitives
and size is immutable.
What else? weak set? again, put a wrapper around it and you got thread-safety.
And what is 'self-repairing'? Can you explain what is it?
--
Best regards,
Igor Stasenko.
