Sounds great

maybe it could be a nice feature to make it possible to choose if you would like to run root entity indexers in parallel or sequentially.

on the MassIndexer there could be an extra method: runRootIndexersSequentially() (or at better name) and then in the BatchCoordinator there could be something like:

private void  doBatchWork(BatchBackend backend) throws InterruptedException {
	int poolSize = rootEntities.lengh;
	if (runRootIndexersSequentially) {
		poolSize = 1;
	}
	ExecutorService executor = Executors.newFixedThreadPool(poolSize, "BatchIndexingWorkspace");
	//rest of code...
}

maybe then the creation of the ThreadPool's in BatchIndexingWorkspace should wait until run(), so there want be created a lot of threads until they are needed.

What do you think?

Have a nice vacation