Performances with gcj

Benjamin de Dardel benjamin.dedardel@gmail.com
Sun Aug 10 18:17:00 GMT 2008


Hi all,

I had to release a program that executes an external process and gets 
its standard output.
I implemented a solution with threads and pipes to redirect inputs and 
outputs (cf PipeTest.java).

I choose the 'find /' command to test it.
I'm very surprised about gcj performances which are 5x slowly than sun jvm.
In fact, I expected that my compiled program would be faster than all jvm.

Do you have an idea about these differences ?
Is that the gnu classpath implementation which is quiet slow ?

Regards,
Benjamin

# test1 : bash
$ time find /
real    2m6.054s
user    0m5.260s
sys     0m6.990s

# test2 : compilation with gcj
$ gcj --main=PipeTest -o test.bin PipeTest.java
$ time test.bin
real    18m50.632s
user    4m56.380s
sys     8m31.940s

real    19m38.148s
user    5m9.660s
sys     9m44.710s

# test3: interpretation with gij
$ gcj -C PipeTest.java
$ time gij PipeTest

real    22m39.882s
user    6m7.580s
sys     10m26.350s

# test4 : interpretation with java
$ javac PipeTest.java
$ time java PipeTest
real    3m35.035s
user    1m18.710s
sys     0m11.730s

##### compilers #####
$ gcj --version
gcj (GCC) 4.2.3 (Ubuntu 4.2.3-2ubuntu6)

$ javac -version
javac 1.6.0_03
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