> From: Leon Rosenberg [mailto:[EMAIL PROTECTED] > Subject: Re: Performance tricks with multiple tomcat instances > > I mean, as long as you are one cpu machine you can be > sure that your threads are never really concurrent and > atomic operations remain atomic (like ++) but in case > of 2 cpus you start to work really concurrent....
Sorry to burst your bubble, but that's simply not true. Even on a single CPU system, the OS only lets a given thread run for so long before switching to another. That switching point can occur at any time, so there's no guarantee that any operation not done under some form of concurrency control will be atomic. Certainly there is less chance of thread interactions on a single CPU, but it's by no means prevented. > I would say, you are right, but if you want to support > http 1.1 keepalives 1.5 threads per user are blocked > simply waiting for incoming requests, so how are you > supposed to server 500 users with 75 threads? I don't think it works that way (at least not in any of the servers I've developed). There's only one thread (per port) waiting on incoming requests; when a request arrives, it's handed off to a worker thread for processing, which normally does its thing, generates the response, and goes back into the pool. (The worker thread may or may not send the response directly.) Keepalives simply reset the connection timer and are quickly discarded. The only time you'll see hundreds of threads actually busy is if they're stuck waiting for an external resource to respond (e.g., data base), or are queued on some locking mechanism - indications of an application architecture problem. - Chuck THIS COMMUNICATION MAY CONTAIN CONFIDENTIAL AND/OR OTHERWISE PROPRIETARY MATERIAL and is thus for use only by the intended recipient. If you received this in error, please contact the sender and delete the e-mail and its attachments from all computers. --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
