Re: GH replacement proposal (includes a bit of Unicode)

[Andreas Rottmann <a.rottmann@gmx.at>]

Marius Vollmer <marius.vollmer@uni-dortmund.de> writes:

>> I'm a little wary of the locking, especially global locking, but I
>> suppose it may well be necessary.  I don't have a strong feeling
>> either way offhand, but presuming for the moment that it is necessary,
>> then is there any way to lock down a particular value rather than the
>> entire heap?
>
> Having a lock for every object would have a high overhead and give you
> very little in terms of performance, I guess.  Also, they would be
> tricky to use.
>
Why would the overhead be significantly larger than for one object?
Pika will have per-object locks, and I think the implementation chosen
has little overhead over global locking.

> When you need to lock two objects, there would be the danger of
> deadlocks, when other code needs to lock the exact same two objects,
> but does it in reverse order.
>
You could probably solve this by having an poeration that does an
"atomic" lock of serveral objects. Naive algorithm:

1) lock all objects you can
2) if that's all:
     fine
   else:
     release all objects locked previously, wait a bit and goto 1)

> You would also have to allow locking an object twice, further
> increasing overhead.
>
Why do you need to lock an object twice?

Andy
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