How much can a native compiler improve performance of a java application?

Question

Hello,
we have a customer with low-end machines who complains very much about the
starting time of an application of us. I dont't know the exact configuration
of the clients but i think the bad perfrmance is because the client has too
few memory and has to swap when the jvm starts.
Could a native compiler like Excelsior JET be a solution or would the
imporvement be only marginal?
Anyone who has experience in this topic?
Thank you in advance!

Answer 1

Could a native compiler like Excelsior JET be a solution or would the
imporvement be only marginal?Excelsior JET only packages up the class files and a JRE into a big blob so that it looks like a single executable. It doesn't actually generate native code for your classes.
There are some limited pure-native compilers (e.g. GCJ - the GNU compiler for Java). Because you also need native-compiled libraries, and those are quite incomplete, only certain basic programs can be compiled down to native form without some major tweaking today.
As to whether it'll improve your performance or not: if your program is computationally intensive (does lots of floating-point math, or other CPU-intensive algorithms), it may improve. If it's I/O, network or database bound, you'll see very little improvement, if any. If it's graphics-bound, you may see some improvement, though the native Swing support with GCJ is limited at this time.
Even with long computationally-intensive programs, you may or may not see an improvement. If you use the server VM (java -server ...), then it does similar things behind your back (optimizing compiles), so that eventually your program speeds up a fair amount (though not to pure-native speeds).