[GitHub] [flink] reswqa commented on a diff in pull request #22381: [FLINK-31763][runtime] Convert requested buffers to overdraft buffers when pool size is decreased

["reswqa (via GitHub)" <gi...@apache.org>]

reswqa commented on code in PR #22381:
URL: https://github.com/apache/flink/pull/22381#discussion_r1164944912


##########
flink-runtime/src/main/java/org/apache/flink/runtime/io/network/buffer/LocalBufferPool.java:
##########
@@ -671,13 +675,20 @@ public void setNumBuffers(int numBuffers) {
 
             currentPoolSize = Math.min(numBuffers, maxNumberOfMemorySegments);
 
-            // reset overdraft buffers
+            // If pool size increases, try to convert overdraft buffer to ordinary buffer.
             while (numberOfRequestedOverdraftMemorySegments > 0
                     && numberOfRequestedMemorySegments < currentPoolSize) {
                 numberOfRequestedOverdraftMemorySegments--;
                 numberOfRequestedMemorySegments++;
             }
 
+            // If pool size decreases, try to convert ordinary buffer to overdraft buffer.
+            while (numberOfRequestedMemorySegments > currentPoolSize
+                    && numberOfRequestedOverdraftMemorySegments < maxOverdraftBuffersPerGate) {
+                numberOfRequestedMemorySegments--;
+                numberOfRequestedOverdraftMemorySegments++;
+            }

Review Comment:
   > From the discussion of [FLINK-31610](https://issues.apache.org/jira/browse/FLINK-31610), this restriction(numberOfRequestedOverdraftMemorySegments <= maxOverdraftBuffersPerGate) will be broken in [FLINK-31764](https://issues.apache.org/jira/browse/FLINK-31764), right?
   
   Yep, you are absolutely right.
   
   > If so, I prefer [FLINK-31764](https://issues.apache.org/jira/browse/FLINK-31764) only refactor the code, not change the overdraft strategy or behavior, and we change the strategy in this PR, WDYT?
   
   Change the semantic/behavior in this PR also make sense to me. Let's update FLINK-31764 to only simply remove the redundant field.



-- 
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.

To unsubscribe, e-mail: issues-unsubscribe@flink.apache.org

For queries about this service, please contact Infrastructure at:
users@infra.apache.org