After doing more testing, I found that this behavior will actually be ok, but I still have a question:
It appears that if the connection dies, Sequoia waits until TCP timeout before returning the results of the attempted query. In other words, the "Unable to remove task" warning and error messages don't occur until after the TCP timeout, whereas if the TCP connection is reestablished immediately following the failed insert, the warning and error messages immediately post. Is this the expected behavior? My initial thoughts were that as soon as the insert fails (times out and aborts) Sequoia should immediately disable the backend and post the errors. It appears that the return blocks until a full TCP failure is detected (assuming a connection failure). Since the backend is going to be disabled anyway, why does it wait for the TCP timeout before it changes the state of the backend? Thanks for all your help, Jon 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> ------------------------------------------------------------------------------------ About Swisslog Swisslog designs solutions in logistics automation that greatly reduce the manual flow of materials and associated information within healthcare facilities. This message may contain legally privileged or confidential information and is therefore addressed to the named persons only. The recipient should inform the sender and delete this message, if he/she is not named as addressee. The sender disclaims any and all liability for the integrity and punctuality of this message. The sender has activated an automatic virus scanning, but does not guarantee the virus free transmission of this message. ________________________________ _______________________________________________ Sequoia mailing list [email protected]<mailto:[email protected]> https://forge.continuent.org/mailman/listinfo/sequoia -- Emmanuel Cecchet FTO @ Frog Thinker Open Source Development & Consulting -- Web: http://www.frogthinker.org email: [EMAIL PROTECTED]<mailto:[EMAIL PROTECTED]> Skype: emmanuel_cecchet This message may contain legally privileged or confidential information and is therefore addressed to the named persons only. The recipient should inform the sender and delete this message, if he/she is not named as addressee. The sender disclaims any and all liability for the integrity and punctuality of this message. The sender has activated an automatic virus scanning, but does not guarantee the virus free transmission of this message.
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