hollow/src/main/java/com/netflix/hollow/api/producer/HollowIncrementalProducer.java
private void executeInParallel(Collection<Object> objList, String description, final Callback callback) {
        SimultaneousExecutor executor = new SimultaneousExecutor(threadsPerCpu, getClass(), description);
        for(final Object obj : objList) {
            executor.execute(() -> callback.call(obj));
        }

        try {
            executor.awaitSuccessfulCompletion();
        } catch(Exception e) {
            throw new RuntimeException(e);
        }
    }
private void executeInParallel(Collection<Object> objList, String description, final Callback callback) {
        SimultaneousExecutor executor = new SimultaneousExecutor(threadsPerCpu, getClass(), description);
        for(final Object obj : objList) {
            executor.execute(() -> callback.call(obj));
        }

        try {
            executor.awaitSuccessfulCompletion();
        } catch(Exception e) {
            throw new RuntimeException(e);
        }
    }
Parallel execution. Modifies the mutation ConcurrentHashMap in parallel based on a Callback.
<p>
Note: This could be replaced with Java 8 parallelStream and lambadas instead of Callback interface
</p>
@param objList
@param callback