This isn't directly related to tomcat, but does relate to the
performance testing people have done over the last couple of days.
I have a section of code in a frequently-called (~3.5 million times per
day) servlet where I had to process based on a parameter that could take
one of 6 different single-character string values. I had been using an
if .. else if construct. Then I discovered that java 1.5 allowed
constructing a switch on strings. So I did some speed testing of a
standalone java class that compared the 6-option switch that vs my
6-step if/elseif.
Under 1.5.0_12, Client vm, the switch was consistently faster, but by
less than 1% (IOW, code readability was more important than the speed gain).
Under 1.6.0_13, Client vm, the if/elseif construct sped up by a factor
of about 10% - 12%, and the switch only about 1%, so the if/elseif was
now about 10% faster, probably worth doing depending on the usage.
Under 1.6.0_13, Server VM, the switch sped up by a factor of 4x from the
1.6 Client run, and the if/elseif only slightly, so now the switch was
about 1.8x faster, definitely worth doing.
I ran these tests several times, varying the order, and got pretty
consistent results across multiple runs. As with the testing I did on
incrementing AtomicIntegers vs Synchronized counters, I was shocked at
how much faster the server vm was than the client one.
Dave
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