zhijiangW commented on a change in pull request #11687:
URL: https://github.com/apache/flink/pull/11687#discussion_r419520547
##########
File path:
flink-runtime/src/main/java/org/apache/flink/runtime/io/network/partition/consumer/RemoteInputChannel.java
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@@ -105,12 +98,15 @@ public RemoteInputChannel(
int maxBackoff,
InputChannelMetrics metrics) {
- super(inputGate, channelIndex, partitionId, initialBackOff,
maxBackoff,
- metrics.getNumBytesInRemoteCounter(),
metrics.getNumBuffersInRemoteCounter());
+ super(inputGate, channelIndex, partitionId, initialBackOff,
maxBackoff, metrics);
this.connectionId = checkNotNull(connectionId);
this.connectionManager = checkNotNull(connectionManager);
- this.bufferManager = new BufferManager(this, 0);
+ // In theory it should get the total number of states to
indicate the numRequiredBuffers.
+ // Since we can not get this information in advance, and
considering only one input channel
+ // will read state at the same time by design, then we give a
maximum value here to reduce
+ // unnecessary interactions with buffer pool during recovery.
+ this.bufferManager = new BufferManager(this, Integer.MAX_VALUE);
Review comment:
As I explained for `LocalInputChannel` case, this `numRequiredBuffers`
setting is only for a bit optimization, actually we can unify them as 0 and
adjust it while really requesting floating buffers in process.
ATM we only have one input channel under unspill, so it makes sense to grab
all the available floating buffers for this channel now. After this channel
finishes unspilling, then it would release all the floating buffers back to
`LocalBufferPool` to be reused by other unspill channel.
There was a bit tricky to design the factor of `numRequiredBuffers` before.
If one exclusive buffer is recycled or a floating buffer is recycled to notify
available for the listener, it would double check whether the current listener
still needs more floating buffers ATM based on `numRequiredBuffers`. If not
needed, then the floating buffer would be return back to local pool to assign
other listeners.
For input channel unspill case, we can assume that the current channel is
always needing more floating buffers until finish, to avoid the floating buffer
back to local pool and request from pool again when need it next time.
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