Yes, I think InetAddress just might do the trick. Thank you Kris! -- Frank W. Zammetti Founder and Chief Software Architect Omnytex Technologies http://www.omnytex.com
On Fri, March 18, 2005 11:24 am, Kris Schneider said: > Will InetAddress.getLocalHost() work for you? > NetworkInterface.getNetworkInterfaces() might also be of interest. Or, you > might want to create yourself an instance of java.rmi.dgc.VMID... > > Quoting "Frank W. Zammetti" <[EMAIL PROTECTED]>: > >> Oh boy, I got a good one! It's only related to Struts in that the >> application in question is Struts-based, so I hope no one minds a >> semi-OT >> question... >> >> Here's the situation... An app I wrote has a daemon thread that is >> spawned >> at startup (from a Struts plugin) that does periodic background >> processing >> tasks. This works great, never had a bit of trouble. >> >> Now though, the app is moving from a single server to a clusted >> environment. >> >> So, what's going to happen is that each server in the cluster will have >> its own instance of the thread running on it. Not a huge problem except >> that I have to be sure only one instance of the thread (i.e., one server >> in the cluster) is executing concurrently. >> >> The easy solution is just a database table that is checked when the >> thread >> wakes up. If there is no entry in it, then there is no other instance >> running, so it can write an entry to the table and go off and do its >> thing. >> >> I want to be extremely certain that no issues arise in terms of one >> instance of the thread reading from the database while another instance >> is >> writing, etc. So, aside from transactional database calls and row-level >> locking, I want to do one more thing: I want the thread to sleep a >> random >> number of seconds (1-300) at startup. This will ensure that, all the >> database locking and such aside, the threads should all be offset from >> one >> another in terms of when they run. >> >> So, I need a random number generated when the thread starts up. As we >> all >> know though, random number generation on most computers that don't have >> something like a Brownian motion sensor attached stuck in a cup of >> boiling >> coffee can't generate truly random numbers. So, in theory, what could >> happen is that if all the servers in the cluster come up at the same >> time, >> the threads could wind up running at the same time regardless of the >> random sleep at the start! It might never happen in reality, small >> fluctuations would probably offset them anyway, but I want to be more >> certain than that. >> >> So now we're at the crux of the problem... >> >> I can't just seed the random number generator with the current time >> because it concievably might not be random enough. So, I thought I >> could >> just tally up the octets of the server's IP address and add that to the >> current time. Then the seed on each server should be different enough. >> >> But, there doesn't appear to be any way to get the server IP address >> independant of a request, so I can't get at it in my plugin. Anyone >> know >> differently? >> >> Assuming that is the case, can anyone think of any other way to seed the >> generator that would ensure a different value on different machines in >> the >> cluster? There are some options like encoding the individual server >> names >> in my app's config file with a different seed value for each, but that >> makes maintenance a pain if a new server is added or one removed or >> addresses simply changed. >> >> Any ideas? Thanks! >> >> -- >> Frank W. Zammetti >> Founder and Chief Software Architect >> Omnytex Technologies >> http://www.omnytex.com > > -- > Kris Schneider <mailto:[EMAIL PROTECTED]> > D.O.Tech <http://www.dotech.com/> > > --------------------------------------------------------------------- > To unsubscribe, e-mail: [EMAIL PROTECTED] > For additional commands, e-mail: [EMAIL PROTECTED] > > --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
