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

[Andreas Rottmann]

Marius Vollmer <address@hidden> writes:

> Andreas Rottmann <address@hidden> writes:
>
>> Marius Vollmer <address@hidden> writes:
>>
>>> 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.
>
> Ahh, I don't know about that implementation.  How large is the
> overhead? (in bits/object, say.  URL perfectly OK.)
>
There is no overhead in bits/object. The locks are allocated
dynamically for each object when requested and released again
afterwards.

>>> 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)
>
> Yes, but I would count this as 'significant overhead' ;-)
>
I assume the case 2) whould be hit seldomly...

Andy
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