/**
* Time a multi-threaded access to a cache.
*
* @return the timing stopwatch
*/
private <V> StopWatch timeMultiThreaded(
String id, final Map<Integer, V> map, ValueFactory<V> factory) throws InterruptedException {
StopWatch stopWatch = new StopWatch(id);
for (int i = 0; i < 500; i++) {
map.put(i, factory.newValue(i));
}
Thread[] threads = new Thread[30];
stopWatch.start("Running threads");
for (int threadIndex = 0; threadIndex < threads.length; threadIndex++) {
threads[threadIndex] =
new Thread("Cache access thread " + threadIndex) {
@Override
public void run() {
for (int j = 0; j < 1000; j++) {
for (int i = 0; i < 1000; i++) {
map.get(i);
}
}
}
};
}
for (Thread thread : threads) {
thread.start();
}
for (Thread thread : threads) {
if (thread.isAlive()) {
thread.join(2000);
}
}
stopWatch.stop();
return stopWatch;
}
@Test
@Ignore("Intended for use during development only")
public void shouldBeFasterThanSynchronizedMap() throws Exception {
Map<Integer, WeakReference<String>> synchronizedMap =
Collections.synchronizedMap(new WeakHashMap<Integer, WeakReference<String>>());
StopWatch mapTime =
timeMultiThreaded(
"SynchronizedMap",
synchronizedMap,
new ValueFactory<WeakReference<String>>() {
@Override
public WeakReference<String> newValue(int v) {
return new WeakReference<String>(String.valueOf(v));
}
});
System.out.println(mapTime.prettyPrint());
this.map.setDisableTestHooks(true);
StopWatch cacheTime =
timeMultiThreaded(
"WeakConcurrentCache",
this.map,
new ValueFactory<String>() {
@Override
public String newValue(int v) {
return String.valueOf(v);
}
});
System.out.println(cacheTime.prettyPrint());
// We should be at least 4 time faster
assertThat(cacheTime.getTotalTimeSeconds(), is(lessThan(mapTime.getTotalTimeSeconds() / 4.0)));
}