When built from eclipse, why is a java program slower than when built from command line?

Question

I did some simple function call and string operation in a loop, the java program runs much faster under command line than launching ( Run as... ) from eclipse...

6 lines of output were printed, each line is around 120 characters. each line is a perf result ranges from 50ms to 300ms.

The total time is a little more than 2 seconds.

"much slower" here means, for certain operations ( function call ), I see 20ms vs 300 ms.

After running on console once, the speed on eclipse catches up!

After I change and build the code in eclipse, the speed on CL will drop if I don't rebuild it with command line.

Looks like some hotspot information is only generated with CL...

Answer 1

Maybe it is just the eclipse console that is slower than your operating systems console? Plus, at a total runtime of ~2 seconds, your benchmark probably is just super inaccurate.