Hi Aaron,
Thanks for your help at this. On my part, the object that is set in the val
property is nothing more than a simple java.lang.String. Haha. We did not
override that equals method (in fact I would punish anyone in my team who does
that) as there is no need to.
Regards
Benjamin Foo
Technical Lead
Kasikornbank CMAS Corporate Project
On-site Project Address
9th Floor (Special Projects Department)
Kasikornbank PCL
1 Soi Kasikornthai
Ratburana Road
10140 Bangkok
Thailand
Head Office Address
eBworx Berhad
7th Floor Menara Merais
1 Jalan 19/3
46300 Petaling Jaya
Selangor DE
Malaysia
Tel: (+6)03-7956 9822
Fax: (+6)03-7957 2661
Mobile: (+6)016-330 0565 (Malaysia)
Mobile: (+66)4-656 1719 (Thailand)
Email: benjaminfoo@xxxxxxxxxx <mailto:benjaminfoo@xxxxxxxxxx>
________________________________
From: Aaron Smuts [mailto:asmuts@xxxxxxxxx]
Sent: Thu 10/11/2005 08:33
To: JCS Developers List
Subject: Spam:Re: Lateral Cache Problems due to ObjectOutputStream Reset
frequency
I can't replicate the problem in jdk 1.4.2 or in
1.3.1.
I suspect that the stream my be checking object
equality with a a cache of previously serialized
object in the stream.
Did you overwrite the equals method on the objects
that you are putting in the cache?
Aaron
--- Aaron Smuts <asmuts@xxxxxxxxx> wrote:
> writeUnshared is new in jdk1.4
>
> I guess we'll have to reset after each send. This
> basically just clears the stream's cache which we
> don't want to use anyway, I think.
>
> Here's the 1.3 javadoc:
>
>
http://java.sun.com/j2se/1.3/docs/api/java/io/ObjectOutputStream.html#reset()
>
>
> --- Aaron Smuts <asmuts@xxxxxxxxx> wrote:
>
> > I think the output stream must think that the
> object
> > is the same as the one previously written.
> Calling
> > reset everytime, or using the writeUnshared method
> > should work. I think writeUnshared will be
> better.
> >
> >
>
http://java.sun.com/j2se/1.4.2/docs/api/java/io/ObjectOutputStream.html#writeUnshared(java.lang.Object)
> >
> > Aaron Smuts
> >
> >
> >
> > --- Aaron Smuts <asmuts@xxxxxxxxx> wrote:
> >
> > > This is strange.
> > >
> > > Can you try on jdk1.4 or above and see if you
> get
> > > the
> > > same problem?
> > >
> > > Does it happen every time?
> > >
> > > Aaron
> > >
> > > --- Benjamin Foo <benjaminfoo@xxxxxxxxxx> wrote:
> > >
> > > > Hi JCS developers,
> > > >
> > > > Recently, I've encountered a wierd behaviour
> > > > regarding the synchronising of data across
> > lateral
> > > > caches. The problem occurs when a given
> > > LateralCache
> > > > begins streaming the LateralElementDescriptor
> > > object
> > > > to other laterals. It is discovered that the
> > > > CacheElement.val property tends to reuse the
> > value
> > > > of a previously sent led (where the keys are
> the
> > > > same). Following is an example of how caches
> > will
> > > > become unsynchornised:
> > > >
> > > > LateralCache1 sends led (key="MyKey",
> > > > value="MyValue1")
> > > >
> > > > LateralCache2 received led (key="MyKey",
> > > > value="MyValue1")
> > > >
> > > > LateralCache1 sends led (key="MyKey",
> > > > value="MyValue1,MyValue2")
> > > >
> > > > LateralCache2 received led (key="MyKey",
> > > > value="MyValue1")
> > > >
> > > >
> > > > I attempted to address this behaviour by
> adding
> > in
> > > > some debugging code:
> > > >
> > > > In the try-catch block just before
> > > > ObjectOutputStream writes the object
> > > >
> > > > oos.writeObject( led );
> > > >
> > > > I added some debugging code at the send method
>
> > > >
> > > > //** Ben DEBUG Code (09/11/2005)
> > > > if ( log.isDebugEnabled() )
> > > > {
> > > > log.debug( "BEN: Sending
> > > > LateralElementDescriptor to other laterals " +
> > > "led
> > > > = " + led + ", led.command = " + led.command +
> > ",
> > > > led.ce = " + led.ce );
> > > > }
> > > >
> > > > Output is:
> > > > <Nov 9, 2005 3:52:07 PM ICT> <DEBUG>
> > > > <LateralTCPSender> BEN: Sending
> > > > LateralElementDescriptor to other laterals led
> =
> > > >
> > >
> >
>
org.apache.jcs.auxiliary.lateral.LateralElementDescriptor@451523
> > > >
> > >
> >
>
<mailto:org.apache.jcs.auxiliary.lateral.LateralElementDescriptor@451523>
> > > > , led.command = 1, led.ce =
> > > > [cacheName=DSMSDataCache,
> > key=LoginValue-GROUPKEY,
> > > > val=[74398d770ac5c563005ae9d6c8b00087,
> > > > 7436cea60ac5c563005ae9d6a093a373], attr = [
> > > > IS_LATERAL = true, IS_SPOOL = true, IS_REMOTE
> =
> > > > true, IS_ETERNAL = false, MaxLifeSeconds = -1,
> > > > IdleTime = -1, CreateTime = 1131526327671,
> > > > LastAccessTime = 1131526327671,
> > > > getTimeToLiveSeconds() = -1, createTime =
> > > > 1131526327671 ]]
> > > >
> > > >
> > > > To my surprise, before writing the object, the
> > led
> > > > value is correct, but at the receiving end at
> > the
> > > > LateralTCPListener, in the Thread's run
> method,
> > > the
> > > > ObjectInputStream reads a stale value:
> > > >
> > > > led = (LateralElementDescriptor)
> > ois.readObject();
> > > >
> > > > Output is:
> > > > <Nov 9, 2005 3:52:08 PM ICT> <DEBUG>
> > > > <LateralTCPListener> receiving
> > > > LateralElementDescriptor from anotherled =
> > > >
> > >
> >
>
org.apache.jcs.auxiliary.lateral.LateralElementDescriptor@5d3aec
> > > >
> > >
> >
>
<mailto:org.apache.jcs.auxiliary.lateral.LateralElementDescriptor@5d3aec>
> > > > , led.command = 1, led.ce =
> > > > [cacheName=DSMSDataCache,
> > key=LoginValue-GROUPKEY,
> > > > val=[7436cea60ac5c563005ae9d6a093a373], attr =
> [
> > > > IS_LATERAL = true, IS_SPOOL = true, IS_REMOTE
> =
> > > > true, IS_ETERNAL = false, MaxLifeSeconds = -1,
> > > > IdleTime = -1, CreateTime = 1131526327671,
> > > > LastAccessTime = 1131526327671,
> > > > getTimeToLiveSeconds() = 16, createTime =
> > > > 1131526327671 ]]
> > > >
> > > >
> > > > I decided to change the constant value for
> > > > RESET_FREQUENCY of the LateralTCPSender class
> to
> > 1
> > > > (reset after every send), and the
> LateralCaches
> > no
> > > > longer have unsynchornised values.
> > > >
> > > > Is there any impact to the performance of JCS
> by
> > > > doing this? Could this be a minor fault with
> the
> > > JDK
> > > > (I'm running on JDK131)?
> > > >
> > > >
> > > >
> > > > Benjamin Foo
> > > > Technical Lead
> > > > Kasikornbank CMAS Corporate Project
> > > >
> > > > On-site Project Address
> > > > 9th Floor (Special Projects Department)
> > > > Kasikornbank PCL
> > > > 1 Soi Kasikornthai
> > > > Ratburana Road
> > > > 10140 Bangkok
> > > > Thailand
> > > >
> > > > Head Office Address
> > > > eBworx Berhad
> > > > 7th Floor Menara Merais
> > > > 1 Jalan 19/3
> > > > 46300 Petaling Jaya
> > > > Selangor DE
> > > > Malaysia
> > > >
>
=== message truncated ===
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