public void initialiseExecutors(boolean isFirstEventArrived) {
        // State only updated when first event arrives to IncrementalAggregationProcessor
        if (isFirstEventArrived) {
            this.isFirstEventArrived = true;
            for (Map.Entry<TimePeriod.Duration, Executor> durationIncrementalExecutorEntry :
                    this.incrementalExecutorMap.entrySet()) {
                if (activeIncrementalDurations.contains(durationIncrementalExecutorEntry.getKey())) {
                    if (durationIncrementalExecutorEntry.getValue() instanceof IncrementalExecutor) {
                        ((IncrementalExecutor) durationIncrementalExecutorEntry.getValue()).setProcessingExecutor(true);
                    } else {
                        ((PersistedIncrementalExecutor) durationIncrementalExecutorEntry.getValue())
                                .setProcessingExecutor(true);
                    }
                }
            }
        }
        this.incrementalExecutorsInitialiser.initialiseExecutors();
    }
Aggregation runtime managing aggregation operations for aggregation definition.
modules/siddhi-core/src/main/java/io/siddhi/core/aggregation/AggregationRuntime.java