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[FLINK-40524][network] Skip the recoveredBuffers monitor on the getNextBuffer hot path for channels that never recover #29058

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[FLINK-40524][network] Skip the recoveredBuffers monitor on the getNextBuffer hot path for channels that never recover #29058

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45 changes: 23 additions & 22 deletions ...c/main/java/org/apache/flink/runtime/io/network/partition/consumer/LocalInputChannel.java
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Original file line number Diff line number Diff line change
Expand Up @@ -559,31 +559,32 @@ protected int peekNextBufferSubpartitionIdInternal() throws IOException {
public Optional<BufferAndAvailability> getNextBuffer() throws IOException {
checkError();

// Read inRecovery and poll the recovered buffer under a single lock acquisition to avoid
// grabbing the monitor twice on the hot path.
boolean inRecovery;
Buffer recoveredBuf = null;
synchronized (recoveredBuffers) {
inRecovery = this.inRecovery;
if (inRecovery && !hasPendingPriorityEvent && !recoveredBuffers.isEmpty()) {
recoveredBuf = recoveredBuffers.poll();
if (needsRecovery) {

@1996fanrui 1996fanrui Sep 1, 2026

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FYI: just wrap inRecovery with if (needsRecovery) {

// Read inRecovery and poll the recovered buffer under a single lock acquisition to
// avoid grabbing the monitor twice on the hot path.
boolean inRecovery;
Buffer recoveredBuf = null;
synchronized (recoveredBuffers) {
inRecovery = this.inRecovery;
if (inRecovery && !hasPendingPriorityEvent && !recoveredBuffers.isEmpty()) {
recoveredBuf = recoveredBuffers.poll();
}
}
}

if (inRecovery) {
// Always return an already-polled recovered buffer first: hasPendingPriorityEvent may
// be flipped to true by a concurrent notifyPriorityEvent() after the poll, and
// re-reading
// it here would otherwise drop this buffer. A pending priority event is served on the
// next getNextBuffer() call instead.
if (recoveredBuf != null) {
return wrapRecoveredBufferAsAvailability(recoveredBuf);
}
if (hasPendingPriorityEvent) {
return pullPriorityFromSubpartitionView();
if (inRecovery) {
// Always return an already-polled recovered buffer first: hasPendingPriorityEvent
// may be flipped to true by a concurrent notifyPriorityEvent() after the poll, and
// re-reading it here would otherwise drop this buffer. A pending priority event is
// served on the next getNextBuffer() call instead.
if (recoveredBuf != null) {
return wrapRecoveredBufferAsAvailability(recoveredBuf);
}
if (hasPendingPriorityEvent) {
return pullPriorityFromSubpartitionView();
}
// Drain not finished yet; block normal upstream data until delivery completes.
return Optional.empty();
}
// Drain not finished yet; block normal upstream data until delivery completes.
return Optional.empty();
}

if (!toBeConsumedBuffers.isEmpty()) {
Expand Down