public NonBlockingIdentityHashMap<Long, TestKey> getMapMultithreaded()
throws InterruptedException, ExecutionException {
final int threadCount = _items.keySet().size();
final NonBlockingIdentityHashMap<Long, TestKey> map =
new NonBlockingIdentityHashMap<Long, TestKey>();
// use a barrier to open the gate for all threads at once to avoid rolling start and no actual
// concurrency
final CyclicBarrier barrier = new CyclicBarrier(threadCount);
final ExecutorService ex = Executors.newFixedThreadPool(threadCount);
final CompletionService<Integer> co = new ExecutorCompletionService<Integer>(ex);
for (Integer type : _items.keySet()) {
// A linked-list of things to insert
List<TestKey> items = _items.get(type);
TestKeyFeederThread feeder = new TestKeyFeederThread(type, items, map, barrier);
co.submit(feeder);
}
// wait for all threads to return
int itemCount = 0;
for (int retCount = 0; retCount < threadCount; retCount++) {
final Future<Integer> result = co.take();
itemCount += result.get();
}
ex.shutdown();
return map;
}
// Concurrent insertion & then iterator test.
public static void testNonBlockingIdentityHashMapIterator() throws InterruptedException {
final int ITEM_COUNT1 = 1000;
final int THREAD_COUNT = 5;
final int PER_CNT = ITEM_COUNT1 / THREAD_COUNT;
final int ITEM_COUNT = PER_CNT * THREAD_COUNT; // fix roundoff for odd thread counts
NonBlockingIdentityHashMap<Long, TestKey> nbhml =
new NonBlockingIdentityHashMap<Long, TestKey>();
// use a barrier to open the gate for all threads at once to avoid rolling
// start and no actual concurrency
final CyclicBarrier barrier = new CyclicBarrier(THREAD_COUNT);
final ExecutorService ex = Executors.newFixedThreadPool(THREAD_COUNT);
final CompletionService<Object> co = new ExecutorCompletionService<Object>(ex);
for (int i = 0; i < THREAD_COUNT; i++) {
co.submit(new NBHMLFeeder(nbhml, PER_CNT, barrier, i * PER_CNT));
}
for (int retCount = 0; retCount < THREAD_COUNT; retCount++) {
co.take();
}
ex.shutdown();
assertEquals("values().size()", ITEM_COUNT, nbhml.values().size());
assertEquals("entrySet().size()", ITEM_COUNT, nbhml.entrySet().size());
int itemCount = 0;
for (TestKey K : nbhml.values()) itemCount++;
assertEquals("values().iterator() count", ITEM_COUNT, itemCount);
}