"AL" == Anders Lindback <[EMAIL PROTECTED]> writes:
AL> Barnet Wagman skrev:
>>
>> By default, the Java compilers includes line numbers in the bytecode
>> they produce. Is there much benefit to compiling production code
>> without line numbers (-o option, I believe), in terms of speed?
AL> Removing the line number and other debugging info makes the
AL> compiled byte code smaller and with a smaller memory footprint
AL> an application may run faster. But only if you have a performance
AL> problem where applicaitons are using too much memory.
AL> (Performance problems usually are one of CPU speed, memory or I/O.)
AL> In theory using the -O optimizer option should make the
AL> code faster - but it all depends on the application
AL> if you see any big change.
I thought that line numbers were kept in the attribute section of the
classfile, and that the bytecodes were identical. Is this not correct?
Also, there is no documented -O option with Sun's 1.4.0 Java compiler
(Search for "-O" on the javac documentation page,
http://java.sun.com/j2se/1.4/docs/tooldocs/solaris/javac.html) although
it is accepted and the command "javac -help" lists it. Compiling a
409 line Java source file produced no difference in bytecode between the
"optimized" compile and the non-optimized compile.
I believe that the rationale for removing the -O functionality is that
mixed-mode interpreters like HotSpot do a much better job of
(on-the-fly) optimization than static, compile-time optimizers can do.
--- Vladimir
Vladimir G. Ivanovichttp://leonora.org/~vladimir
2770 Cowper St. [EMAIL PROTECTED]
Palo Alto, CA 94306-2447 +1 650 678 8014
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