> I mean, when do you know that current jvm is fully used > and that you should start a new one and balance the load > on two? Interesting question. Generally, I'd suggest that you do a load test. You increase the load against the Tomcat instance until the CPU that Tomcat is using isn't increasing any more but the client service time is. This suggests that you've reached the scalability limit of a single Tomcat address space. Then, graph your results. You'll often find a sharp angle in the graph where response time increases sharply with load. Back off from this point a little (say 10%) and that's your maximum throughput for the single JVM, > Also, how do you know that current machine has enough load > and can't support any more requests, and load > should be balanced on two machines? This is easier to do. Assuming you are using Unix, use tools like top(1m), mpstat(1m) on Solaris and ps(1) to check CPU usage. Check memory usage (and paging activity) with vmstat(1m). For NT, PerfMon provides the same sort of facilities via a GUI. For Solaris you can also use the SEToolkit freeware package - it comes with a tool called "Zoom" that provides instant feedback on whether important areas of the machine are overloaded or not. Cheers, Eoin. -----Original Message----- From: Bora Paksoy [mailto:[EMAIL PROTECTED]] Sent: Sunday, July 15, 2001 5:21 AM To: [EMAIL PROTECTED] Subject: When to start a new JVM? Hi there; I am actually a java developer who was asked to manage some Tomcat instance;) Hence, this question may sound dumb, but excuse my sys-admin skills. Anyways, I know that you can start multiple-jvms and even different instances on different machines, but I was wondering how people decide when to start a new JVM? I mean, when do you know that current jvm is fully used and that you should start a new one and balance the load on two? Also, how do you know that current machine has enough load and can't support any more requests, and load should be balanced on two machines? Is there any tool that tells you that one specific jvm process is fully loaded, likewise is there any tool that tells you that this machine is fully loaded and load should be distributed on different machines ? Thanks, Baho. __________________________________________________ Do You Yahoo!? Get personalized email addresses from Yahoo! Mail http://personal.mail.yahoo.com/
