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 = [EMAIL PROTECTED]
<mailto:[EMAIL PROTECTED]> , 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 = [EMAIL PROTECTED] <mailto:[EMAIL
PROTECTED]> , 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
Tel: (+6)03-7956 9822
Fax: (+6)03-7957 2661
Mobile: (+6)016-330 0565 (Malaysia)
Mobile: (+66)4-656 1719 (Thailand)
Email: [EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]>
---------------------------------------------------------------------
To unsubscribe, e-mail: [EMAIL PROTECTED]
For additional commands, e-mail: [EMAIL PROTECTED]
