what means this different in time for the run same program on flink cluster

I run program on cluster Flink contain one master and one slave and calculates the time in the four times found a difference in the time what means this different in time for the same program 1 min 37 secs 133 msecs 7 mins 13 secs 147 msecs 5 mins 24 secs 748 msecs 1 min 47 secs 19 msecs -

what means this different in time for the run same program

I run program on cluster Flink contain one master and one slave and calculates the time in the four times found a difference in the time what means this different in time for the same program 1 min 37 secs 133 msecs 7 mins 13 secs 147 msecs 5 mins 24 secs 748 msecs 1 min 47 secs 19 msecs