[Mono-dev] ObjectPool

[Greg Young]

We have had some moving forward in our mono stability issues. I
figured I would start up a chat here about one place that seems to be
causing many problems.


https://github.com/mono/mono/blob/master/mcs/class/corlib/System.Collections.Concurrent/ObjectPool.cs

I am not really sure the code here is actually thread safe... Maybe it
doesn't need to be for some reason?

We have added volatiles for add/remove index (yuriy pointed out that
threads were often stuck at line 86) but even with that im still not
sure its actually threadsafe. There are some weird edge conditions
that seem to be here (like if CompareExchange fails 3 times it will
just never set the remove index and continue on).

Somebody has obviously spent a lot of time thinking about this code
and optimizing it. I want to make sure we get the full "why" behind
things so we dont a) waste time b) introduce issues.

Greg

-- 
Le doute n'est pas une condition agréable, mais la certitude est absurde.