public Integer call() throws Exception {
_barrier.await();
int count = 0;
for (TestKey item : _items) {
if (_map.contains(item._id)) {
System.err.printf("COLLISION DETECTED: %s exists\n", item.toString());
}
final TestKey exists = _map.putIfAbsent(item._id, item);
if (exists == null) {
count++;
} else {
System.err.printf(
"COLLISION DETECTED: %s exists as %s\n", item.toString(), exists.toString());
}
}
return count;
}
