Hi all,
please review this patch which attempts to clean up synchronization and
improve scalability when
defining and getting java.lang.Package objects.
webrev: http://cr.openjdk.java.net/~redestad/8060130/webrev.02/
bug: https://bugs.openjdk.java.net/browse/JDK-8060130
Testing: jtreg, UTE vm.parallel_class_loading.testlist, various benchmarks
Torturing the retrieval code with a simple microbenchmark[1] shows that
the existing code
could cause bottlenecks, but also that the proposed patch works slightly
faster even in
uncontended cases:
Benchmark Mode Samples Score Score error
Units
baseline, 1 thread:
o.s.SimpleBench.getClassPackage thrpt 10 11.621 0.618
ops/us
o.s.SimpleBench.getPackage thrpt 10 41.754 3.381
ops/us
o.s.SimpleBench.getPackages thrpt 10 0.009 0.000 ops/us
baseline, 2 threads:
o.s.SimpleBench.getClassPackage thrpt 10 7.884 1.977 ops/us
o.s.SimpleBench.getPackage thrpt 10 17.013 8.079
ops/us
o.s.SimpleBench.getPackages thrpt 10 0.004 0.001 ops/us
patch applied, 1 thread:
o.s.SimpleBench.getClassPackage thrpt 10 13.519 0.170
ops/us
o.s.SimpleBench.getPackage thrpt 10 59.999 0.988
ops/us
o.s.SimpleBench.getPackages thrpt 10 0.019 0.001 ops/us
patch applied, 2 threads:
o.s.SimpleBench.getClassPackage thrpt 10 19.181 3.688
ops/us
o.s.SimpleBench.getPackage thrpt 10 79.708 31.220
ops/us
o.s.SimpleBench.getPackages thrpt 10 0.025 0.006 ops/us
/Claes
[1]
package org.sample;
import org.openjdk.jmh.annotations.*;
@State(Scope.Thread)
public class SimpleBench {
@Benchmark
public Package[] getPackages() {
return Package.getPackages();
}
@Benchmark
public Package getClassPackage() {
return this.getClass().getPackage();
}
@Benchmark
public Package getPackage() {
return Package.getPackage("java.util.zip");
}
}
