【flink源码解读 】flink 生成watermark的默认时间间隔

默认间隔是200ms

(1) 在 StreamExecutionEnvironmennt的方法有体现

@PublicEvolving
public void setStreamTimeCharacteristic(TimeCharacteristic characteristic) {
	this.timeCharacteristic = Preconditions.checkNotNull(characteristic);
	if (characteristic == TimeCharacteristic.ProcessingTime) {
		getConfig().setAutoWatermarkInterval(0);
	} else {
		getConfig().setAutoWatermarkInterval(200);
	}
}

如果要修改这个WatermarkInterval时间：

（2）org.apache.flink.api.common.ExecutionConfig:

private long autoWatermarkInterval = 200;

// 可以通过这个方法来修改默认的WatermarkInterval

/**
 * Sets the interval of the automatic watermark emission. Watermarks are used throughout
 * the streaming system to keep track of the progress of time. They are used, for example,
 * for time based windowing.
 *
 * <p>Setting an interval of {@code 0} will disable periodic watermark emission.
 *
 * @param interval The interval between watermarks in milliseconds.
 */
   @PublicEvolving
   public ExecutionConfig setAutoWatermarkInterval(long interval) {
       Preconditions.checkArgument(interval >= 0, "Auto watermark interval must not be negative.");
       this.autoWatermarkInterval = interval;
       return this;
   }