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https://issues.apache.org/jira/browse/FLINK-7416?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16258969#comment-16258969
]
ASF GitHub Bot commented on FLINK-7416:
---------------------------------------
Github user pnowojski commented on a diff in the pull request:
https://github.com/apache/flink/pull/4533#discussion_r151932203
--- Diff:
flink-runtime/src/main/java/org/apache/flink/runtime/io/network/netty/CreditBasedClientHandler.java
---
@@ -0,0 +1,364 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.flink.runtime.io.network.netty;
+
+import org.apache.flink.core.memory.MemorySegment;
+import org.apache.flink.core.memory.MemorySegmentFactory;
+import org.apache.flink.runtime.io.network.buffer.Buffer;
+import org.apache.flink.runtime.io.network.buffer.FreeingBufferRecycler;
+import
org.apache.flink.runtime.io.network.netty.exception.LocalTransportException;
+import
org.apache.flink.runtime.io.network.netty.exception.RemoteTransportException;
+import
org.apache.flink.runtime.io.network.netty.exception.TransportException;
+import org.apache.flink.runtime.io.network.netty.NettyMessage.AddCredit;
+import
org.apache.flink.runtime.io.network.partition.PartitionNotFoundException;
+import
org.apache.flink.runtime.io.network.partition.consumer.InputChannelID;
+import
org.apache.flink.runtime.io.network.partition.consumer.RemoteInputChannel;
+
+import org.apache.flink.shaded.netty4.io.netty.channel.Channel;
+import org.apache.flink.shaded.netty4.io.netty.channel.ChannelFuture;
+import
org.apache.flink.shaded.netty4.io.netty.channel.ChannelFutureListener;
+import
org.apache.flink.shaded.netty4.io.netty.channel.ChannelHandlerContext;
+import
org.apache.flink.shaded.netty4.io.netty.channel.ChannelInboundHandlerAdapter;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.io.IOException;
+import java.net.SocketAddress;
+import java.util.ArrayDeque;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ConcurrentMap;
+import java.util.concurrent.atomic.AtomicReference;
+
+/**
+ * Channel handler to read the messages of buffer response or error
response from the
+ * producer, to write and flush the unannounced credits for the producer.
+ */
+class CreditBasedClientHandler extends ChannelInboundHandlerAdapter {
+
+ private static final Logger LOG =
LoggerFactory.getLogger(CreditBasedClientHandler.class);
+
+ /** Channels, which already requested partitions from the producers. */
+ private final ConcurrentMap<InputChannelID, RemoteInputChannel>
inputChannels = new ConcurrentHashMap<>();
+
+ /** Channels, which will notify the producers about unannounced credit.
*/
+ private final ArrayDeque<RemoteInputChannel> inputChannelsWithCredit =
new ArrayDeque<>();
+
+ private final AtomicReference<Throwable> channelError = new
AtomicReference<>();
+
+ private final ChannelFutureListener writeListener = new
WriteAndFlushNextMessageIfPossibleListener();
+
+ /**
+ * Set of cancelled partition requests. A request is cancelled iff an
input channel is cleared
+ * while data is still coming in for this channel.
+ */
+ private final ConcurrentMap<InputChannelID, InputChannelID> cancelled =
new ConcurrentHashMap<>();
+
+ private volatile ChannelHandlerContext ctx;
--- End diff --
Why is this variable `volatile`? Does it have to be? I see that it was
carried over from `PartitionRequestClientHandler` by @uce in some old bug
[fix](https://github.com/apache/flink/commit/d433ba9f032e5361ae894562b7a8be13cd3efe13),
but I don't understand it. @NicoK?
> Implement Netty receiver outgoing pipeline for credit-based
> -----------------------------------------------------------
>
> Key: FLINK-7416
> URL: https://issues.apache.org/jira/browse/FLINK-7416
> Project: Flink
> Issue Type: Sub-task
> Components: Network
> Reporter: zhijiang
> Assignee: zhijiang
> Fix For: 1.5.0
>
>
> This is a part of work for credit-based network flow control.
> The related works are :
> * We define a new message called {{AddCredit}} to notify the incremental
> credit during data shuffle.
> * Whenever an {{InputChannel}}’s unannounced credit goes up from zero, the
> channel is enqueued in the pipeline.
> * Whenever the channel becomes writable, it takes the next {{InputChannel}}
> and sends its unannounced credit. The credit is reset to zero after each sent.
> * That way, messages are sent as often as the network has capacity and
> contain as much credit as available for the channel at that point in time.
> Otherwise, it would only add latency to the announcements and not increase
> throughput.
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