zhijiangW commented on a change in pull request #7911: [FLINK-11082][network]
Fix the logic of getting backlog in sub partition
URL: https://github.com/apache/flink/pull/7911#discussion_r264508867
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File path:
flink-runtime/src/main/java/org/apache/flink/runtime/io/network/partition/ResultSubpartition.java
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@@ -116,52 +115,58 @@ protected Throwable getFailureCause() {
public abstract boolean isReleased();
- /**
- * Gets the number of non-event buffers in this subpartition.
- *
- * <p><strong>Beware:</strong> This method should only be used in tests
in non-concurrent access
- * scenarios since it does not make any concurrency guarantees.
- */
- @VisibleForTesting
- public int getBuffersInBacklog() {
- return buffersInBacklog;
- }
-
/**
* Makes a best effort to get the current size of the queue.
* This method must not acquire locks or interfere with the task and
network threads in
* any way.
*/
public abstract int unsynchronizedGetNumberOfQueuedBuffers();
+ /**
+ * Gets the number of non-event buffers in this subpartition.
+ */
+ public abstract int getBuffersInBacklog();
+
+ /**
+ * @param lastBufferAvailable whether the last buffer in this
subpartition is available for consumption
+ * @return the number of non-event buffers in this subpartition
+ */
+ protected int getBuffersInBacklog(boolean lastBufferAvailable) {
+ assert Thread.holdsLock(buffers);
+
+ if (lastBufferAvailable) {
+ return buffersInBacklog;
+ } else {
+ return Math.max(buffersInBacklog - 1, 0);
+ }
+ }
+
/**
* Decreases the number of non-event buffers by one after fetching a
non-event
* buffer from this subpartition (for access by the subpartition views).
- *
- * @return backlog after the operation
*/
- public int decreaseBuffersInBacklog(Buffer buffer) {
+ public void decreaseBuffersInBacklogUnsafe(boolean isBuffer) {
Review comment:
I misunderstood the semantic of `Unsafe` before. I define the `Unsafe` based
on the external calling not internal implementation of
`decreaseBuffersInBacklog`. In other words, if external method calls
`decreaseBuffersInBacklog`, it should confirm the buffers are synchronized in
the external method to call this safe, otherwise external method should call
`decreaseBuffersInBacklogUnsafe`.
Now I understand your point of definition, and it seems more reasonable
based on internal confirmation of `decreaseBuffersInBacklog`. I would revert
this change as before.
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