Hibernate Search synchronous execution in main thread

Question

It seems that Hibernate Search synchronous execution uses other threads than the calling thread for parallel execution.

How do I execute the Hibernate Search executions serially in the calling thread?

The problem seems to be in the org.hibernate.search.backend.impl.lucene.QueueProcessors class :

private void runAllWaiting() throws InterruptedException {
        List<Future<Object>> futures = new ArrayList<Future<Object>>( dpProcessors.size() );
        // execute all work in parallel on each DirectoryProvider;
        // each DP has it's own ExecutorService.
        for ( PerDPQueueProcessor process : dpProcessors.values() ) {
            ExecutorService executor = process.getOwningExecutor();
            //wrap each Runnable in a Future
            FutureTask<Object> f = new FutureTask<Object>( process, null );
            futures.add( f );
            executor.execute( f );
        }
        // and then wait for all tasks to be finished:
        for ( Future<Object> f : futures ) {
            if ( !f.isDone() ) {
                try {
                    f.get();
                }
                catch (CancellationException ignore) {
                    // ignored, as in java.util.concurrent.AbstractExecutorService.invokeAll(Collection<Callable<T>>
                    // tasks)
                }
                catch (ExecutionException error) {
                    // rethrow cause to serviced thread - this could hide more exception:
                    Throwable cause = error.getCause();
                    throw new SearchException( cause );
                }
            }
        }
    }

A serial synchronous execution would happen in the calling thread and would expose context information such as authentication information to the underlying DirectoryProvider.