[GitHub] [flink] 1996fanrui commented on a diff in pull request #20233: [FLINK-28474][checkpoint] Simplify the ChannelStateWriterImpl due to concurrent unaligned checkpoint isn't supported

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1996fanrui commented on code in PR #20233:
URL: https://github.com/apache/flink/pull/20233#discussion_r923185089


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flink-runtime/src/main/java/org/apache/flink/runtime/checkpoint/channel/ChannelStateWriterImpl.java:
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@@ -60,89 +63,78 @@
 public class ChannelStateWriterImpl implements ChannelStateWriter {
 
     private static final Logger LOG = LoggerFactory.getLogger(ChannelStateWriterImpl.class);
-    private static final int DEFAULT_MAX_CHECKPOINTS =
-            1000; // includes max-concurrent-checkpoints + checkpoints to be aborted (scheduled via
-    // mailbox)

Review Comment:
   Hi @pnowojski 
   
   From the comment, we can get that the `ConcurrentMap<Long, ChannelStateWriteResult> results;` saves ongoingCheckpoints and abortedCheckpoints. 
   
   But the checkpoints that were aborted before start were not saved. We want aborted checkpoints to ignore start. So I introduced the ` NavigableSet<Long> abortedCheckpointIds;` to save all aborted checkpointIds. 
   
   - If checkpointId is aborted before start, it will be saved into this set. 
   - When the start is called, if checkpointId in this set, the start should be ignored.
   
   And introduced the `long ongoingCheckpointId;` to save the ongoing checkpointId. Because the concurrent unaligned checkpoint isn't supported, so the `long` is enough. And checkpoints with checkpointId less than `ongoingCheckpointId` should be aborted. So I remove these checkpointIds when the ongoingCheckpointId is updated. 
   
   What do you think?



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