I'm not as concerned about the time it took for the controller to post a 
failure.

My problem is that once the controller did post a failure, when I tried to show 
the backend statistics, it hung the console until I tried to do another insert.

As soon as the controller posted an insert failure from the initial query, 
Sequoia knew that the backend had a problem.  I need to know that as soon as 
Sequoia does.  But the only way I can get that information is to ask the 
controller about the state of the backends.  I didn't get a response until the 
next failed insert, which then finally disabled the backend.

What is the fastest way to determine if Sequoia had any kind of a problem when 
performing a query?

From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Emmanuel Cecchet
Sent: Thursday, September 04, 2008 11:19 AM
To: Sequoia general mailing list
Subject: Re: [Sequoia] State delay when connection lost

Jonathan,

The speed problem is due to TCP timeouts. The only way to detect an unplugged 
cable is to wait for the TCP timeout to expire (JDBC drivers use TPC 
connections and Sequoia JDBC driver uses a UDP ping on top of that).
The TCP timeout depends on your OS settings and are independent of Sequoia.

Hope this helps,
Emmanuel


When running Sequoia with two backends connected through a 10/100 switch, I 
pulled the Ethernet cable from one machine.  I then did an insert on the 
virtual DB.  It took about 15 seconds for the controller to post a failure.  
Immediately thereafter, I used the console to get the status of the backend 
that was disconnected.  After typing the command "show backend *" it took well 
over a minute for the results to be posted.  I then attempted another insert 
and the stats immediately showed after that.  I can't wait for the next write; 
I need to be able to know immediately when the controller posts a failure.

I tried the same test using my own console application and the JMX interface.  
In my app it simply connects to the JMX server and starts polling for the 
backend read/write/initialized status.  I got the same result - it hung for 
over a minute while trying to poll until I tried to do another insert.  Is 
there any way to quickly find the state of the database?  I have to notify the 
users of my software as soon as Sequoia determines there's a problem with a 
backend.  I need this information ASAP.  The only thing that I can come up with 
at this point is to parse the log entries from the controller, because it seems 
to be doing a better job of notifying when there's a problem.  But this seems 
hacky, and I don't want to do it that way.

I want to use JMX to receive notifications from Sequoia when there's a problem. 
 I don't see any notifications being posted.  Are there any?  If not, is there 
a faster way to query that information?

Thanks,

Jonathan Stockho
Software Developer

Swisslog Healthcare Solutions
10825 E. 47th Avenue
Denver, CO  80239
Phone: 303-373-7814
FAX: 303-373-7872
e-mail: [EMAIL PROTECTED]<mailto:[EMAIL PROTECTED]>
Internet: www.swisslog.com<http://www.swisslog.com>

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About Swisslog
Swisslog designs solutions in logistics automation that greatly reduce the 
manual flow of materials and associated information within healthcare 
facilities.



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Open Source Development & Consulting

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Skype: emmanuel_cecchet

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