why does Jetty not use all allocated memory?

we develop the webapp with Grails. In productio the webapp runs on Jetty. We used JMeter to run performance-test and yourkit to analyse the memory consumtion of jetty.

We started Jetty with params -Xms1500m -Xmx1500m, so in yourkit we can also see the allocated memory is about 1,5gb. But Jetty does not use it all, all time always about 300 - 500m and delivers bad performance. can serve only few requests/s.

• CPU ist not full loaded, all times only about 50%
• Jetty is running with default se开发者_如何学Pythonttings, 6.1.21 is used
• MySQL queries are simple, DB size is small and runs on the same machine as Jetty, could not be the problems
• Logs r written over FileAppender to HDD
• JMeter produces enought requests
• Yourkit shows the number of live threads is about 60

so how can we force jetty to use all allocated memory for better performance?

Thx you very much!

The problem is probably not the memory, it looks like you have enough.

You have probably other points of contention, for example exclusive-locks.

I suggest you take several snapshots of your threads, to examine where they are stuck. You should find the contention.