Re: [boost] A fast-pathed rw-mutex algorithm for Boost...

From: Chris Thomasson (cristom_at_[hidden])
Date: 2006-10-24 13:42:02

"Anthony Williams" <anthony_w.geo_at_[hidden]> wrote in message 
news:zmbl66cr.fsf_at_yahoo.com...
> "Chris Thomasson" <cristom_at_[hidden]> writes:
>> "Anthony Williams" <anthony_w.geo_at_[hidden]> wrote in message
>> news:d58h7nlv.fsf_at_yahoo.com...
>>> The way I see it, the ideal is that a waiting writer will block any 
>>> fresh
>>> readers until all the current readers have gone away, but once that
>>> happens,
>>> and the lock is released, the waiting writer and the waiting readers 
>>> will
>>> compete equally.

[...]

>> Again, if your rw-mutex is getting hit with enough writes to even begin 
>> to
>> start to starve the readers, then the user of the rw-mutex is using it
>> improperly... IMHO  of course...
>
> I agree that preventing writers starving should be sufficient in most 
> cases. I
> just happen to think that it's less than ideal.
>
> I was imagining a system with several hundred readers, and a couple of
> writers. If the writers take sufficiently long, you might find that you 
> have
> one waiting on the other. The readers then get starved if you give writers
> priority, just as the writers get starved if you give readers priority.

Well, if you are using hundreds of reader threads, then basically any 
rw-mutex is less than ideal in most cases, IMO:

http://groups.google.com/group/comp.programming.threads/msg/fdc665e616176dce

Humm...