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mingleizhang commented on FLINK-4421: ------------------------------------- Hi, Stephan. Thanks for reporting this. I would like to know, Under what circumstances will lead to clock updates ? that is what you said can lead to negative duration. And I would like to try read {{Introduce a Clock utility for monotonous system timestamps}}. Like today I run a code like {{System.currentTimeMillis()}} return 12345. Tomorrow, I run {{System.currentTimeMillis()}} return 12145. So, It can lead to negative duration. > Make clocks and time measurements monotonous > -------------------------------------------- > > Key: FLINK-4421 > URL: https://issues.apache.org/jira/browse/FLINK-4421 > Project: Flink > Issue Type: Improvement > Components: Core > Reporter: Stephan Ewen > Priority: Minor > > Currently, many places use {{System.currentTimeMillis()}} to acquire > timestamps or measure time intervals. > Since this relies on the system clock, and the system clock is not > necessarily monotonous (in the presence of clock updates), this can lead to > negative duration and decreasing timestamps where increasing timestamps are > expected. -- This message was sent by Atlassian JIRA (v6.4.14#64029)