Hi Lance On 19.01.22 23:35, Campbell, Lance wrote: > On a Tomcat 9.x dedicated Linux server with 16G of memory, how much memory > would you allocate for the OS? > > Assume there is no file processing taking place. Also assume Tomcat is > communicating primarily with a PostgreSQL database and Apache web server each > running on their own dedicated servers. The Tomcat application server is the > only thing running on the Linux server.
It depends (TM) Without knowing your application, the load (e.g. number of concurrent users) and general setup, there's no way to tell. I'd rather handle the question the other way around: How much memory does (your application on) Tomcat require. Tomcat itself is happy with just a little bit of memory, but applications vary widely. Also, some applications are memory-bound, some are I/O-bound, some are CPU-bound. So memory might not be your bottleneck to worry about. You should load-test your application with a realistic load (plus margin) and keep an eye on memory consumption. But in the end you'll find out what is the first bottleneck to appear. It might not be memory. But to come back closer to your original question: I recommend to deactivate swapspace for production servers, and configure -Xms equal to -Xmx, so that you find shortages of memory early (when you start the application) rather than Sunday night at 3am. You might want to leave 1-2G for the OS and start testing this way, or rather test how little memory your app requires to run and add margin. My rule of thumb is: The more memory there is to be claimed in GC, the longer a full GC run takes. Often, many short but frequent GC runs are preferable to fewer but longer lasting. (I didn't check if this still applies to the newer generation of garbage collectors, so take this GC-statement with a grain of salt) Olaf --------------------------------------------------------------------- To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
