RFR(s): 8078463: optimize java/util/Map/Collisions.java

Stuart Marks stuart.marks at oracle.com
Thu May 14 01:44:38 UTC 2015

Hi all,

Please review this change to optimize a test. Basically the test did string 
formatting for every assertion, but the string was thrown away if the assertion 
passed -- the most common case. The change is to do the string formatting only 
when an assertion fails and information needs to be printed out.

Thanks to Andrey Zakharov for discovering and investigating this.

Bug report:




On my (new, fast) laptop, with JVM options -Xcomp -XX:+DeoptimizeALot -client, 
the unmodified test takes about 21.4 seconds to run. The modified test takes 
only 12.3 seconds.

Note that I have added several overloads of check() with different arguments. I 
tried an alternative, which is a varargs version of check():

     static void	check(boolean cond, String fmt,	Object... args) {
         if (cond) {
         } else {
             fail(String.format(fmt, args));

This of course is much simpler code, but it took 14.2 seconds, about 15% slower 
than the proposed version. Is the simpler code worth the slowdown? I could go 
either way.



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