flink-issues mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From GitBox <...@apache.org>
Subject [GitHub] [flink] sunhaibotb commented on a change in pull request #8124: [FLINK-11877] Implement the runtime handling of the InputSelectable interface
Date Thu, 18 Apr 2019 08:04:05 GMT
sunhaibotb commented on a change in pull request #8124: [FLINK-11877] Implement the runtime
handling of the InputSelectable interface
URL: https://github.com/apache/flink/pull/8124#discussion_r276556081
 
 

 ##########
 File path: flink-runtime/src/main/java/org/apache/flink/runtime/io/network/partition/consumer/SingleInputGate.java
 ##########
 @@ -184,6 +184,9 @@
 	/** A timer to retrigger local partition requests. Only initialized if actually needed.
*/
 	private Timer retriggerLocalRequestTimer;
 
+	/** Flag indicating whether there is available data. */
+	private volatile boolean moreDataAvailable = false;
 
 Review comment:
   > We always should use either this BufferOrEvent#moreAvailable() or relay on listeners/futures
to inform us that the availability has changed
   
   I don't think they can accurately determine the state (available or unavailable). Considering
the following execution sequences, the task thread finally sees the same thing that `BufferOrEvent#moreAvailable`
 is unavailable and receives a non-null notification, but the last actual state of `InputGate`
is different, the former is available, and the latter is unavailable.
   
   Case 1:
   1. Initial State: `InputGate` is data available
   2. (**Task Thread**) Call `InputGate#pollNextBufferOrEvent()`
   3. (**Task Thread**)  `InputGate` become empty after being polled a `BufferOrEvent`
   4. (**Task Thread**)  Assign `BufferOrEvent#moreAvailable` to false before returning
   5. (**Network Thread**) Data arrives at `InputGate`  which triggers the non-empty notification
   6. (**Task Thread**) `InputGate#pollNextBufferOrEvent()` returns, `BufferOrEvent#moreAvailable`
is false and recieves a `non-empty` notification
   
   Case 2:
   1. Initial State: `InputGate` is data unavailable
   2. (**Task Thread**) Call `InputGate#pollNextBufferOrEvent()`
   3. (**Network Thread**) Data arrives at `InputGate`  which triggers the non-empty notification
   4. (**Task Thread**)  `InputGate` become empty after being polled a `BufferOrEvent`
   5. (**Task Thread**)  Assign `BufferOrEvent#moreAvailable` to false before returning
   6. (**Task Thread**) `InputGate#pollNextBufferOrEvent()` returns, `BufferOrEvent#moreAvailable`
is false and recieves a `non-empty` notification

----------------------------------------------------------------
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.
 
For queries about this service, please contact Infrastructure at:
users@infra.apache.org


With regards,
Apache Git Services

Mime
View raw message