Query on state of ValueState getting lost

[Parth Sarathy]

Hi,

I am using flink 1.8.2, event time stream for sliding window transformation
with custom trigger. Window size is 15 seconds, slide size is also 15
seconds with 30 seconds allowed lateness. In the trigger implementation
couple of class level ValueStateDescriptors are used, the corresponding
ValueState variables are updated/initialized in the onElement method and
these are used in onEventTime method. On sending two records at 90 seconds
interval, with current time updated in timestamp field of the messages,
onEventTime method was called when the second record arrived, for the window
with the first record, and in this method the values in the corresponding
ValueState variables were found to be null. When the two records were sent
with time difference of 75 seconds the values in the ValueStates were
present.

What could be the reason for the values in ValueStates becoming null when
time difference between the messages was around 90 seconds or higher? I
checked that the TTL in the default StateTtlConfig is very high, so I am not
sure why the states expired.
 
Thanks,
Parth Sarathy



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[Congxian Qiu]

Hi

Could you please check whether the key and namespace are the same? when getting a result for the value state, Flink will use current key and current namespace to retrieve the result.

Parth Sarathy <[hidden email]> 于2019年12月22日周日 下午9:54写道：

Hi,

I am using flink 1.8.2, event time stream for sliding window transformation
with custom trigger. Window size is 15 seconds, slide size is also 15
seconds with 30 seconds allowed lateness. In the trigger implementation
couple of class level ValueStateDescriptors are used, the corresponding
ValueState variables are updated/initialized in the onElement method and
these are used in onEventTime method. On sending two records at 90 seconds
interval, with current time updated in timestamp field of the messages,
onEventTime method was called when the second record arrived, for the window
with the first record, and in this method the values in the corresponding
ValueState variables were found to be null. When the two records were sent
with time difference of 75 seconds the values in the ValueStates were
present.

What could be the reason for the values in ValueStates becoming null when
time difference between the messages was around 90 seconds or higher? I
checked that the TTL in the default StateTtlConfig is very high, so I am not
sure why the states expired.

Thanks,
Parth Sarathy



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