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https://issues.apache.org/jira/browse/HADOOP-18024?focusedWorklogId=690554&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-690554
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ASF GitHub Bot logged work on HADOOP-18024:
-------------------------------------------
Author: ASF GitHub Bot
Created on: 04/Dec/21 18:49
Start Date: 04/Dec/21 18:49
Worklog Time Spent: 10m
Work Description: virajjasani commented on a change in pull request #3719:
URL: https://github.com/apache/hadoop/pull/3719#discussion_r762454550
##########
File path:
hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/ipc/Server.java
##########
@@ -1530,15 +1530,30 @@ private void closeCurrentConnection(SelectionKey key,
Throwable e) {
InetSocketAddress getAddress() {
return (InetSocketAddress)acceptChannel.socket().getLocalSocketAddress();
}
-
+
+ protected void configureSocketChannel(SocketChannel channel) throws
IOException {
Review comment:
Same here, good to annotate with IA.Private and VFT
##########
File path:
hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/ipc/Server.java
##########
@@ -1325,7 +1325,7 @@ public String toString() {
}
/** Listens on the socket. Creates jobs for the handler threads*/
- private class Listener extends Thread {
+ protected class Listener extends Thread {
Review comment:
Would have been better if we could keep this private, but it seems we
have no better way if we want to test this change (Thanks for the test btw). If
we are going to go forward with this, we should annotate this as
`@VisibleForTesting` and `@InterfaceAudience.Private`.
Let's also get some expert advice on this. cc @aajisaka @ayushtkn
@jojochuang
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Issue Time Tracking
-------------------
Worklog Id: (was: 690554)
Time Spent: 1h 40m (was: 1.5h)
> SocketChannel is not closed when IOException happens in
> Server$Listener.doAccept
> --------------------------------------------------------------------------------
>
> Key: HADOOP-18024
> URL: https://issues.apache.org/jira/browse/HADOOP-18024
> Project: Hadoop Common
> Issue Type: Bug
> Components: ipc
> Affects Versions: 3.2.2
> Reporter: Haoze Wu
> Priority: Major
> Labels: pull-request-available
> Time Spent: 1h 40m
> Remaining Estimate: 0h
>
> This is a follow-up of HADOOP-17552.
> When the symptom described in HADOOP-17552 happens, the client may time out
> in 2min, according to the default RPC timeout configuration specified in
> HADOOP-17552. Before this timeout, the client just waits, and does not know
> this issue happens.
> However, we recently found that actually the client doesn’t need to waste
> this 2min, and the server’s availability can be also improved. If the
> IOException happens in line 1402 or 1403 or 1404, we can just close this
> problematic `SocketChannel` and continue to accept new socket connections.
> The client side can also be aware of the close socket immediately, instead of
> waiting 2min.
> The old implementation:
> {code:java}
> //hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/ipc/Server.java
> public void run() {
> while (running) {
> // ...
> try {
> // ...
> while (iter.hasNext()) {
> // ...
> try {
> if (key.isValid()) {
> if (key.isAcceptable())
> doAccept(key); // line 1348
> }
> } catch (IOException e) { // line 1350
> }
> // ...
> }
> } catch (OutOfMemoryError e) {
> // ...
> } catch (Exception e) {
> // ...
> }
> }
> } {code}
> {code:java}
> //hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/ipc/Server.java
> void doAccept(SelectionKey key) throws InterruptedException, IOException,
> OutOfMemoryError {
> ServerSocketChannel server = (ServerSocketChannel) key.channel();
> SocketChannel channel;
> while ((channel = server.accept()) != null) { // line 1400
> channel.configureBlocking(false); // line 1402
> channel.socket().setTcpNoDelay(tcpNoDelay); // line 1403
> channel.socket().setKeepAlive(true); // line 1404
> Reader reader = getReader();
> Connection c = connectionManager.register(channel,
> this.listenPort, this.isOnAuxiliaryPort);
> // If the connectionManager can't take it, close the connection.
> if (c == null) {
> if (channel.isOpen()) {
> IOUtils.cleanup(null, channel);
> }
> connectionManager.droppedConnections.getAndIncrement();
> continue;
> }
> key.attach(c); // so closeCurrentConnection can get the object
> reader.addConnection(c);
> }
> } {code}
>
> We propose that the following implementation is better:
> {code:java}
> void doAccept(SelectionKey key) throws InterruptedException, IOException,
> OutOfMemoryError {
> ServerSocketChannel server = (ServerSocketChannel) key.channel();
> SocketChannel channel;
> while ((channel = server.accept()) != null) { // line 1400
> try {
> channel.configureBlocking(false); // line 1402
> channel.socket().setTcpNoDelay(tcpNoDelay); // line 1403
> channel.socket().setKeepAlive(true); // line 1404
> } catch (IOException e) {
> LOG.warn(...);
> try {
> channel.socket().close();
> channel.close();
> } catch (IOException ignored) { }
> continue;
> }
> // ...
> }
> }{code}
> The advantages include:
> # {*}In the old implementation{*}, the `ServerSocketChannel` was abandoned
> due to the single exception in this single `SocketChannel`, because the
> exception handler is in line 1350. {*}In the new implementation{*}, we use a
> try-catch to handle the exception in line 1402 or 1403 or 1404, then the
> `ServerSocketChannel` can continue to accept new connections, and don’t need
> to go back to the line 1348 in the next while loop in the run method.
> # {*}In the old implementation{*}, the client (another endpoint of this
> `SocketChannel`) is not aware of this issue, because the `SocketChannel` is
> accepted and not closed. {*}In the new implementation{*}, we close the
> `SocketChannel` when the IOException happens, then the client will
> immediately get EOF from the socket. Then the client can choose to retry or
> throw an exception, by the client’s discretion.
>
> We have confirmed that this patch works as expected, in our local machine.
>
> This code pattern was adopted by other communities. For example, in Kafka
> [https://github.com/apache/kafka/blob/23e9818e625976c22fe6d4297a5ab76b01f92ef6/core/src/main/scala/kafka/network/SocketServer.scala#L714-L740]:
> {code:java}
> /**
> * Accept a new connection
> */
> private def accept(key: SelectionKey): Option[SocketChannel] = {
> val serverSocketChannel = key.channel().asInstanceOf[ServerSocketChannel]
> val socketChannel = serverSocketChannel.accept()
> try {
> connectionQuotas.inc(endPoint.listenerName,
> socketChannel.socket.getInetAddress, blockedPercentMeter)
> configureAcceptedSocketChannel(socketChannel)
> Some(socketChannel)
> } catch {
> case e: TooManyConnectionsException =>
> info(...)
> close(endPoint.listenerName, socketChannel)
> None
> case e: ConnectionThrottledException =>
> // ...
> None
> case e: IOException =>
> error(...)
> close(endPoint.listenerName, socketChannel)
> None
> }
> }
> /**
> * Close `channel` and decrement the connection count.
> */
> def close(listenerName: ListenerName, channel: SocketChannel): Unit = {
> if (channel != null) {
> // ...
> closeSocket(channel)
> }
> }
> protected def closeSocket(channel: SocketChannel): Unit = {
> CoreUtils.swallow(channel.socket().close(), this, Level.ERROR)
> CoreUtils.swallow(channel.close(), this, Level.ERROR)
> }
> {code}
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