Manu Zhang created FLINK-4862: --------------------------------- Summary: NPE on EventTimeSessionWindows with ContinuousEventTimeTrigger Key: FLINK-4862 URL: https://issues.apache.org/jira/browse/FLINK-4862 Project: Flink Issue Type: Bug Components: Streaming, Windowing Operators Reporter: Manu Zhang
h3. what's the error ? The following NPE error is thrown when EventTimeSessionWindows with ContinuousEventTimeTrigger is used. {code} Caused by: java.lang.NullPointerException at org.apache.flink.streaming.api.windowing.triggers.ContinuousEventTimeTrigger.clear(ContinuousEventTimeTrigger.java:91) at org.apache.flink.streaming.runtime.operators.windowing.WindowOperator$Context.clear(WindowOperator.java:768) at org.apache.flink.streaming.runtime.operators.windowing.WindowOperator$2.merge(WindowOperator.java:310) at org.apache.flink.streaming.runtime.operators.windowing.WindowOperator$2.merge(WindowOperator.java:297) at org.apache.flink.streaming.runtime.operators.windowing.MergingWindowSet.addWindow(MergingWindowSet.java:196) at org.apache.flink.streaming.runtime.operators.windowing.WindowOperator.processElement(WindowOperator.java:297) at org.apache.flink.streaming.runtime.io.StreamInputProcessor.processInput(StreamInputProcessor.java:183) at org.apache.flink.streaming.runtime.tasks.OneInputStreamTask.run(OneInputStreamTask.java:66) at org.apache.flink.streaming.runtime.tasks.StreamTask.invoke(StreamTask.java:271) at org.apache.flink.runtime.taskmanager.Task.run(Task.java:609) at java.lang.Thread.run(Thread.java:745) {code} h3. how to reproduce ? use {{ContinuousEventTimeTrigger}} instead of the default {{EventTimeTrigger}} in [SessionWindowing | https://github.com/apache/flink/blob/master/flink-examples/flink-examples-streaming/src/main/java/org/apache/flink/streaming/examples/windowing/SessionWindowing.java#L84] example. h3. what's the cause ? When two session windows are being merged, the states of the two {{ContinuousEventTimeTrigger}} are merged as well and the new namespace is the merged window. Later when the context tries to delete {{Timer}} from the old trigger and looks up the timestamp by the old namespace, null value is returned. -- This message was sent by Atlassian JIRA (v6.3.4#6332)