Lately, a facebook comment of mine on the subject of Java’s slowness has proved quite popular, so here goes: Here’s a listing of a few Hello World programs and running times for them (including startup, which is a big deal in Java) on my laptop:
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| $ grep '^model name' /proc/cpuinfo | head -1
model name: Intel(R) Core(TM) i5-3337U CPU @ 1.80GHz
$ uname -a
Linux orca 3.11.0-14-generic #21-Ubuntu SMP Tue Nov 12 17:04:55 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux
|
The following script will be timed:
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| #!/bin/bash
n=$1
shift
for ((i=0; i < $n; i++)); do
$@" > /dev/null
done
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Times are for n=100.
C
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| #include <stdio.h>
int main(int argc, char * argv[]) {
printf("Hello, world!\n");
return 0;
}
/* Result: 0.17s
* ...unless you give it a .cc extension, and then it's 0.30s!
* It turns out that gcc/g++ guess the language from the file extension.
*/
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C++
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| #include <iostream>
int main(int argc, char * argv[]) {
std::cout << "Hello, world!" << std::endl;
return 0;
}
// Result: 0.30s
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Python
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| #!/usr/bin/python
print "Hello, world!"
# Result: 1.33s
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Java
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| public class Hello {
public static void main(String args[]) {
System.out.println("Hello, world!");
}
}
// Result: 8.60s. No, I am not kidding.
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There you have it. Sun’s Java takes 28x-51x as much time to run “Hello World” (startup included) than native applications, and (shockingly, in my opinion) over 6x as much as non-precompiled Python. That’s meaningless for long-running applications, but is a very big deal for small, often-run ones.