@Override
    public synchronized void shutdown() {
        // It shouldn't be possible to queue tasks during shutdown.
        try {
            allowTaskQueueFill = false;
            clearTaskStore();
        } catch (final RuntimeException e) {
            LOGGER.error(e.getMessage(), e);
        }
    }
Make sure the task store isn't allowed to be filled until this node has
run startup() and has not run shutdown().
stroom-processor/stroom-processor-impl/src/main/java/stroom/processor/impl/ProcessorTaskQueueManagerImpl.java