Java Thread Performance: Collection Test
/*
Java Threads, 3rd Edition
By Scott Oaks, Henry Wong
3rd Edition September 2004
ISBN: 0-596-00782-5
*/
import java.util.*;
import java.util.concurrent.*;
import java.util.concurrent.atomic.*;
public class CollectionTest {
static int nLoops;
public static void main(String[] args) {
nLoops = 10000;
doTest(new Vector());
doTest(new ArrayList());
doTest(Collections.synchronizedList(new ArrayList()));
nLoops = Integer.parseInt(args[0]);
System.out.println("Starting synchronized vector test");
cleanGC();
Timestamp syncTS = new Timestamp();
doTest(new Vector());
syncTS.stop();
System.out.println("Synchronized vector took " + syncTS);
System.out.println("Starting unsynchronized vector test");
cleanGC();
Timestamp unsyncTS = new Timestamp();
unsyncTS.stop();
System.out.println("Unsynchronized vector took " + unsyncTS);
double d = ((double) (syncTS.elapsedTime() - unsyncTS.elapsedTime()))
/ nLoops;
System.out.println("Unsynchronized operation saves " + d + " "
+ syncTS.units() + " per call");
System.out.println("Starting synchronized array list test");
cleanGC();
syncTS = new Timestamp();
doTest(Collections.synchronizedList(new ArrayList()));
syncTS.stop();
System.out.println("Synchronized array list took " + syncTS);
System.out.println("Starting unsynchronized array list test");
cleanGC();
unsyncTS = new Timestamp();
doTest(new ArrayList());
unsyncTS.stop();
System.out.println("Unsynchronized aray list took " + unsyncTS);
d = ((double) (syncTS.elapsedTime() - unsyncTS.elapsedTime())) / nLoops;
System.out.println("Unsynchronized operation saves " + d + " "
+ syncTS.units() + " per call");
}
static void cleanGC() {
System.gc();
System.runFinalization();
System.gc();
}
static void doTest(List l) {
Integer n = new Integer(0);
for (int i = 0; i < nLoops; i++)
l.add(n);
}
}
class Timestamp {
private long startTime;
private long stopTime;
private boolean stopped = false;
private TimeUnit ts;
public Timestamp() {
this(TimeUnit.NANOSECONDS);
}
public Timestamp(TimeUnit ts) {
this.ts = ts;
start();
}
public void start() {
startTime = System.nanoTime();
stopped = false;
}
public void stop() {
stopTime = System.nanoTime();
stopped = true;
}
public long elapsedTime() {
if (!stopped)
throw new IllegalStateException("Timestamp not stopped");
return ts.convert(stopTime - startTime, TimeUnit.NANOSECONDS);
}
public String toString() {
try {
return elapsedTime() + " " + ts;
} catch (IllegalStateException ise) {
return "Timestamp (not stopped)";
}
}
public String units() {
return ts.toString();
}
}
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