public static <T> int getDistinctResultCount(int num, Callable<T> callable)
    throws Throwable {
    IdentityHashMap<T, Object> found = new IdentityHashMap<T, Object>();
    Collection<SyncThread<T>> threads = getCompletedThreads(num, callable);
    for (SyncThread<T> s : threads) {
      found.put(s.getResult(), new Object());
    }
    return found.size();
  }
Get the distinct result count for the given callable at the given
concurrency.

@param <T> the type of the callable
@param num the concurrency
@param callable the callable to invoke
@return the number of distinct (by identity) results found
@throws Throwable if an exception occurred in one of the invocations
src/main/java/net/spy/memcached/compat/SyncThread.java