Nick Lawson wrote:
>
> I'm pretty sure try{}catch{} catch blocks add NO overhead to code,
> unless the exception actually gets thrown. But exceptions are
> supposed to be
> exceptional, so who cares how slow it is ?
>
> Check out how exception handling is implemented in Java byte-code
> in the Java Virtual Machine Specification, 4.7.3 - The Code
> Attribute.
Times for attached program (JDK1.2pre2, glibc2.1, RH6, 200MHZ PPro,
500000000 iterations):
No JIT sunwjit tya
------ ------- ---
With try/catch 278793 17925 33894
Without 237905 15364 35803
%slower 17.2% 16.7% -5.3%
I'd be surprised to see a zero-overhead try/catch, although tya seems to
be on to something :-).
Results are unaffected by -O compilation.
Nathan
--------------------------------------------------------
import java.util.*;
public class Hello
{
public static void main(String[] argv) throws Exception
{
int count = Integer.parseInt(argv[0]);
Date date1 = new Date();
boolean foobar = false;
for (int i = 0; i < count;)
{
try
{
i++;
if (foobar) throw new Exception();
// Try to make optimization-resistant :-)
foobar = foobar && true;
}
catch (Exception e) { }
}
Date date2 = new Date();
Date date3 = new Date();
for (int i = 0; i < count;)
{
i++;
if (foobar) throw new Exception();
// Try to make optimization-resistant :-)
foobar = foobar && true;
}
Date date4 = new Date();
System.out.println("First loop (try): " +
(date2.getTime() - date1.getTime()));
System.out.println("Second loop (no try): " +
(date4.getTime() - date3.getTime()));
}
}
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