jackrabbit-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Bart van der Schans <b.vandersch...@onehippo.com>
Subject Re: [jr3 microkernel] Write skew
Date Thu, 01 Dec 2011 15:33:06 GMT
On Thu, Dec 1, 2011 at 4:26 PM, Stefan Guggisberg
<stefan.guggisberg@gmail.com> wrote:
> On Thu, Dec 1, 2011 at 3:49 PM, Thomas Mueller <mueller@adobe.com> wrote:
>> Hi,
>>
>>> A test-and-set operation necessarily requires at least some level of
>>> atomicity which can quickly become a bottleneck for a clustered setup.
>>
>> Test-and-set is a problem in a clustered 'eventually consistent' model,
>> that's true. I don't know how test-and-set could be used in that way.
>>
>> Possibly the easiest solution is that each node modification sets the node
>> type again (to the expected value) even if the user didn't change it.
>>
>>
>> But I don't think we should try to increase concurrency of write
>> operations within the *same* repository because that's not a problem at
>> all.
>
> i beg to differ ;)
>
> in jr2 saves are serialized. IMO that's a *real* problem, especially when
> saving large change sets. this problem can be addressed e.g. with an
> MVCC based model.

Yes, I agree. It's something I've seen many times in the field
(consider saving a large pdf in a cms). What makes the current
situation even worse is that you can't scale out the writes in a
cluster since all writes are serialized for the whole cluster. If you
could scale out and have concurrent writes on different cluster nodes
the problem would be much less worse.

Bart

Mime
View raw message