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From "Corin Moss" <Corin.M...@tvnz.co.nz>
Subject RE: Locks within AbstractReadWriteStore
Date Mon, 08 Mar 2004 07:51:46 GMT

Hiya,

JCS certainly has an implementation of a r/w lock:

http://jakarta.apache.org/turbine/jcs/xref/org/apache/jcs/utils/locking/
ReadWriteLock.html

The indexed disk cache certainly uses it, as I suspect does any other
cache which needs such a thing. So I guess we should be fine to remove
the A-R-W dependency?

It's worth noting that JCS even implements a r/w lock for its JISP
implementation, where JISP doesn't do such a thing on its own.

Does this require a vote? :)

Corin




-----Original Message-----
From: Carsten Ziegeler [mailto:cziegeler@s-und-n.de]
Sent: Monday, 8 March 2004 8:40 p.m.
To: dev@cocoon.apache.org
Subject: RE: Locks within AbstractReadWriteStore


The A-R-W store is just a dump default implementation. The old stores in
Cocoon/Avalon weren't synchronized properly, so they sometimes suffered
from threading issues.
A first easy-to-do solution was the A-R-W store with using the locks.
Now, I haven't looked into JCS, but I guess they are doing the
synchronization inside JCS (I hope). If this is true, we don't do any
syncing/locking in our Store and simply defer the work to JCS.

HTH
Carsten


________________________________

	From: Corin Moss [mailto:Corin.Moss@tvnz.co.nz]
	Sent: Sunday, March 07, 2004 11:56 PM
	To: dev@cocoon.apache.org
	Subject: Locks within AbstractReadWriteStore



	Hi Guys,

	When I first started looking at the persistent store I mentioned
the read/write locks contained within AbstractReadWriteStore as a
potential issue.  Under load test with the new JCS based store I'm still
seeing really high iowait usage after about 10-12 hours (similar to what
I noticed with the JISP based store.)  I suspect that there may indeed
be a problem somewhere within this part of the store.

	The cache is no longer corrupt after the test (it was with the
old JISP store), but it does still take a long time to get anything
written to it. What I'll try and do is perform a similar test, outside
of the Cocoon environment using the JCS library and see if I can
recreate this.

	I also notice that there's a new release of
EDU.oswego.cs.dl.util.concurrent - so I'll have a look at this as well.

	Carsten - I noticed your tag on the A-R-W store - do you have
any more info on this? I realise that it's an Avalon component, but I
guess it started its life here with all the other store classes? 

	Let me know if anyone has more experience with this particular
class
:)

	Corin


	Corin Moss
	Lead Developer
	TVNZ Interactive

	+64 9 916 7367
	+64 21 403 054
	corin.moss@tvnz.co.nz




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