The minimum thread priority is 1, maximum is 10 and medium or normal is 5. See:
http://java.sun.com/j2se/1.4.2/docs/api/constant-values.html#java.lang.Thread.NORM_PRIORITY You can set a "good neighbor poilicy with MIN_PRIORITY. Hunter on Servlets covers this with a daemon servlet. Jack On Tue, 28 Dec 2004 11:49:13 -0500, Frank W. Zammetti <[EMAIL PROTECTED]> wrote: > > Dennis Payne wrote: > > Frank, > > I'm using threads and didn't know I was vulnerable. > > I'm not sure "vulnerable" is really the right word, but I'll go with it :) > > > Here's how I've > > done it. I created a class that implements runnable and call its > > initialize method from a servlet init method at application startup. > > The initialize method creates a thread and sets a low priority for it. > > Roughly what I do too, except that my class extends Thread and I kick it > off from a Struts plug-in. Same effect though. > > > The run method sleeps the thread and wakes it every two minutes. > > A processing class contains the methods that queries the database > > (postgres). > > Same here. I think I wake my threads every minute though. > > > 1. Is this what you call a daemon thread? > > Nope. If you take a peak at the javadocs for the Thread class, you'll > see a method setDaemon(boolean). This marks a thread as a daemon > thread. The difference, if I remember correctly, is that the JVM won't > shut down until all remaining threads are daemon threads. Threfore, if > you spawn a "normal" thread, you can hold up the JVM from shutting down > properly. > > This is in fact the situation I had... My Tomcat instance could never be > properly shut down because the threads I had spawned where not daemon > threads. Marking them as such solved that problem. > > To the best of my knowledge, being a daemon thread doesn't implicitly > say anything about a threads priority. I think you could have a daemon > thread set at high priority if you wanted. I suspect most daemon > threads are bumped to a lower priority though, as I do. > > > 2. Is this better done using cron? if so how do I ensure that it runs > > > > with a lower priority than my application code? > > Phil > > This is a matter of opinion, and there are some reasonable arguments for > both points of view. > > My personal opinion is that if you have some periodic process that is > going to need portions of your system, whether it's resources available > in the container or shared code, as you do, then a low-priority daemon > thread spawned at application startup is a good approach, assuming you > write it carefully and solidly. > > For instance, in my case, my daemon threads do some record aging in the > database, so to me it makes sense to share the same connection pool as > the application itself. I also use a number of classes and functions > that are part of the webapp itself, and I don't like the idea of > duplicating the code for a cron job to use (sure, could just be a matter > of setting up a classpath to those classes, but it's an extra > dependency, and that doesn't thrill me). > > But, if these tasks were volatile in any way, or they had to run > independently of the app itself no matter what, the cron job approach > would probably be preferable. > > As for ensuring it runs at a lower priority than your application code, > when running via cron, that's an answer I can't give you. I'm frankly a > Unix newbie, more or less, so someone else out there would be better > suited to answer that. I think you'd have to have it run at a lower > priority than your app server, and I'm sure there's switches to set > priority of jobs, but I don't know them. > > -- > Frank W. Zammetti > Founder and Chief Software Architect > Omnytex Technologies > http://www.omnytex.com > > --------------------------------------------------------------------- > To unsubscribe, e-mail: [EMAIL PROTECTED] > For additional commands, e-mail: [EMAIL PROTECTED] > > -- ------------------------------ "You can lead a horse to water but you cannot make it float on its back." ~Dakota Jack~ "You can't wake a person who is pretending to be asleep." ~Native Proverb~ "Each man is good in His sight. It is not necessary for eagles to be crows." ~Hunkesni (Sitting Bull), Hunkpapa Sioux~ ----------------------------------------------- "This message may contain confidential and/or privileged information. If you are not the addressee or authorized to receive this for the addressee, you must not use, copy, disclose, or take any action based on this message or any information herein. If you have received this message in error, please advise the sender immediately by reply e-mail and delete this message. Thank you for your cooperation." --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
