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Fixes #5306 - Default jetty.*.acceptors should be 1. (#6236) 

* Fixes #5306 - Default jetty.*.acceptors should be 1.

Changed the acceptor default to 1, with -1 calculating a value based on the number of cores.
Updated documentation.
Fixed a glitch in ManagedSelector.getMaxSelectedKeys() to return long, not double.

Signed-off-by: Simone Bordet <simone.bordet@gmail.com>
This commit is contained in:
Simone Bordet 2021-05-20 09:34:07 +02:00 committed by GitHub
parent 1d5d8071ba
commit 67e2b4af2f
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9 changed files with 169 additions and 16 deletions
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14
documentation/jetty-documentation/src/main/asciidoc/operations-guide/modules/module-http.adoc
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@ -29,22 +29,26 @@ The network port that Jetty listens to for clear-text HTTP/1.1 connections -- de
`jetty.http.idleTimeout`::
The amount of time a connection can be idle (i.e. no bytes received and no bytes sent) until the server decides to close it to save resources -- default `30` seconds.
`jetty.http.acceptors`::
The number of threads that compete to accept connections -- default -1 (i.e. an accept heuristic decides the value based on the number of cores).
The number of threads that compete to accept connections -- default 1. Use -1 to let the accept heuristic decides the value; the current heuristic calculates a value based on the number of cores).
Refer to xref:og-module-http-acceptors[this section] for more information about acceptor threads.
`jetty.http.selectors`::
The number of NIO selectors (with an associated thread) that manage connections -- default -1 (i.e. a select heuristic decides the value based on the number of cores).
The number of NIO selectors (with an associated thread) that manage connections -- default -1 (i.e. a select heuristic decides the value; the current heuristic calculates a value based on the number of cores).
[[og-module-http-acceptors]]
====== Configuration of Acceptors
Accepting connections is a blocking operation, so a thread is blocked in the `accept()` call until a connection is accepted, and other threads are blocked on the lock acquired just before the `accept()` call.
Accepting connections from remote clients may be configured as a blocking operation, or a non-blocking operation.
When accepting connections is configured as a blocking operation (the number of acceptors is greater than zero), a thread is blocked in the `accept()` call until a connection is accepted, and other acceptor threads (if any) are blocked on the lock acquired by the accepting thread just before the `accept()` call.
When the accepting thread accepts a connection, it performs a little processing of the just accepted connection, before forwarding it to other components.
During this little processing other connections may be established; if there is only one accepting thread, the newly established connections are waiting for the accepting thread to finish the processing of the previously accepted connection and call again `accept()`.
Servers that manage a very high number of connections that may (naturally) come and go, or that handle inefficient protocols that open and close connections very frequently (such as HTTP/1.0) may benefit of an increased number of acceptor threads.
Servers that manage a very high number of connections that may (naturally) come and go, or that handle inefficient protocols that open and close connections very frequently (such as HTTP/1.0) may benefit of an increased number of acceptor threads, so that when one acceptor thread processes a just accepted connection, another acceptor thread can immediately take over accepting connections.
// TODO: expand on acceptors=0 and non-blocking accepts
When accepting connections is configured as a non-blocking operation (the number of acceptors is zero), then the server socket is set in non-blocking mode and added to a NIO selector.
In this way, no dedicated acceptor threads exist: the work of accepting connections is performed by the selector thread.
[[og-module-http-selectors]]
====== Configuration of Selectors

10
documentation/jetty-documentation/src/main/asciidoc/operations-guide/modules/module-ssl.adoc
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@ -29,13 +29,13 @@ Among the configurable properties, the most relevant are:
`jetty.ssl.port`::
The network port that Jetty listens to for secure connections -- default `8443`.
`jetty.http.idleTimeout`::
`jetty.ssl.idleTimeout`::
The amount of time a connection can be idle (i.e. no bytes received and no bytes sent) until the server decides to close it to save resources -- default `30000` milliseconds.
`jetty.http.acceptors`::
The number of threads that compete to accept connections -- default -1 (i.e. an accept heuristic decides the value based on the number of cores).
`jetty.ssl.acceptors`::
The number of threads that compete to accept connections -- default 1. Use -1 to let the accept heuristic decides the value; the current heuristic calculates a value based on the number of cores).
Refer to xref:og-module-http-acceptors[this section] for more information about acceptor threads.
`jetty.http.selectors`::
The number of NIO selectors (with an associated thread) that manage connections -- default -1 (i.e. a select heuristic decides the value based on the number of cores).
`jetty.ssl.selectors`::
The number of NIO selectors (with an associated thread) that manage connections -- default -1 (i.e. a select heuristic decides the value; the current heuristic calculates a value based on the number of cores).
Refer to xref:og-module-http-selectors[this section] for more information about selector threads.
The module properties to configure the KeyStore and TLS parameters are:

2
jetty-io/src/main/java/org/eclipse/jetty/io/ManagedSelector.java
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@ -158,7 +158,7 @@ public class ManagedSelector extends ContainerLifeCycle implements Dumpable
}
@ManagedAttribute(value = "Maximum number of selected keys", readonly = true)
public double getMaxSelectedKeys()
public long getMaxSelectedKeys()
{
return _keyStats.getMax();
}

2
jetty-server/src/main/config/etc/jetty-http.xml
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@ -22,7 +22,7 @@
<Arg>
<New id="httpConnector" class="org.eclipse.jetty.server.ServerConnector">
<Arg name="server"><Ref refid="Server" /></Arg>
<Arg name="acceptors" type="int"><Property name="jetty.http.acceptors" default="-1"/></Arg>
<Arg name="acceptors" type="int"><Property name="jetty.http.acceptors" default="1"/></Arg>
<Arg name="selectors" type="int"><Property name="jetty.http.selectors" default="-1"/></Arg>
<Arg name="factories">
<Array type="org.eclipse.jetty.server.ConnectionFactory">

2
jetty-server/src/main/config/etc/jetty-ssl.xml
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@ -15,7 +15,7 @@
<Arg>
<New id="sslConnector" class="org.eclipse.jetty.server.ServerConnector">
<Arg name="server"><Ref refid="Server" /></Arg>
<Arg name="acceptors" type="int"><Property name="jetty.ssl.acceptors" default="-1"/></Arg>
<Arg name="acceptors" type="int"><Property name="jetty.ssl.acceptors" default="1"/></Arg>
<Arg name="selectors" type="int"><Property name="jetty.ssl.selectors" default="-1"/></Arg>
<Arg name="factories">
<Array type="org.eclipse.jetty.server.ConnectionFactory">

2
jetty-server/src/main/config/modules/http.mod
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@ -26,7 +26,7 @@ etc/jetty-http.xml
# jetty.http.idleTimeout=30000
## The number of acceptors (-1 picks a default value based on number of cores).
# jetty.http.acceptors=-1
# jetty.http.acceptors=1
## The number of selectors (-1 picks a default value based on number of cores).
# jetty.http.selectors=-1

2
jetty-server/src/main/config/modules/ssl.mod
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@ -28,7 +28,7 @@ etc/jetty-ssl-context.xml
# jetty.ssl.idleTimeout=30000
## The number of acceptors (-1 picks a default value based on number of cores).
# jetty.ssl.acceptors=-1
# jetty.ssl.acceptors=1
## The number of selectors (-1 picks a default value based on number of cores).
# jetty.ssl.selectors=-1

1
jetty-server/src/main/java/org/eclipse/jetty/server/AbstractNetworkConnector.java
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@ -30,7 +30,6 @@ import org.eclipse.jetty.util.thread.Scheduler;
@ManagedObject("AbstractNetworkConnector")
public abstract class AbstractNetworkConnector extends AbstractConnector implements NetworkConnector
{
private volatile String _host;
private volatile int _port = 0;

150
jetty-server/src/test/java/org/eclipse/jetty/server/ServerConnectorAcceptTest.java Normal file
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@ -0,0 +1,150 @@
//
// ========================================================================
// Copyright (c) 1995-2021 Mort Bay Consulting Pty Ltd and others.
//
// This program and the accompanying materials are made available under the
// terms of the Eclipse Public License v. 2.0 which is available at
// https://www.eclipse.org/legal/epl-2.0, or the Apache License, Version 2.0
// which is available at https://www.apache.org/licenses/LICENSE-2.0.
//
// SPDX-License-Identifier: EPL-2.0 OR Apache-2.0
// ========================================================================
//
package org.eclipse.jetty.server;
import java.io.IOException;
import java.net.Socket;
import java.nio.charset.StandardCharsets;
import java.util.Collection;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.CyclicBarrier;
import java.util.concurrent.TimeUnit;
import java.util.stream.IntStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.eclipse.jetty.http.HttpStatus;
import org.eclipse.jetty.http.HttpTester;
import org.eclipse.jetty.io.ManagedSelector;
import org.eclipse.jetty.server.handler.AbstractHandler;
import org.junit.jupiter.params.ParameterizedTest;
import org.junit.jupiter.params.provider.ValueSource;
import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertNotNull;
import static org.junit.jupiter.api.Assertions.assertTrue;
public class ServerConnectorAcceptTest
{
@ParameterizedTest
@ValueSource(ints = {0, 1, 2})
public void testAccept(int acceptors) throws Exception
{
Server server = new Server();
ServerConnector connector = new ServerConnector(server, acceptors, 1);
server.addConnector(connector);
server.setHandler(new AbstractHandler()
{
@Override
public void handle(String target, Request jettyRequest, HttpServletRequest request, HttpServletResponse response)
{
jettyRequest.setHandled(true);
}
});
server.start();
int runs = 4;
try
{
for (int r = 0; r < runs; ++r)
{
test(acceptors, connector);
}
}
finally
{
server.stop();
}
}
private void test(int acceptors, ServerConnector connector) throws InterruptedException
{
int threads = 8;
int iterations = 4096;
CyclicBarrier barrier = new CyclicBarrier(threads + 1);
CountDownLatch latch = new CountDownLatch(threads * iterations);
IntStream.range(0, threads)
.mapToObj(t -> new Thread(() ->
{
try
{
assertTrue(awaitBarrier(barrier));
long start = System.nanoTime();
for (int i = 0; i < iterations; ++i)
{
try (Socket socket = new Socket("localhost", connector.getLocalPort()))
{
String request = "GET / HTTP/1.1\r\n" +
"Host: localhost\r\n" +
"Connection: close\r\n" +
"\r\n";
socket.getOutputStream().write(request.getBytes(StandardCharsets.UTF_8));
HttpTester.Response response = HttpTester.parseResponse(socket.getInputStream());
assertNotNull(response);
assertEquals(HttpStatus.OK_200, response.getStatus());
}
catch (IOException x)
{
x.printStackTrace();
}
finally
{
latch.countDown();
}
}
long elapsed = System.nanoTime() - start;
System.err.printf("%d acceptors, %d threads, %d requests each, time = %d ms%n",
acceptors,
threads,
iterations,
TimeUnit.NANOSECONDS.toMillis(elapsed));
}
finally
{
assertTrue(awaitBarrier(barrier));
}
}))
.forEach(Thread::start);
// Wait for all the threads to be ready.
assertTrue(awaitBarrier(barrier));
// Wait for all the threads to be finished.
assertTrue(awaitBarrier(barrier));
// Verify that all requests succeeded.
assertTrue(latch.await(15, TimeUnit.SECONDS));
Collection<ManagedSelector> selectors = connector.getSelectorManager().getBeans(ManagedSelector.class);
selectors.stream()
.map(s -> String.format("avg selected keys = %.3f, selects = %d", s.getAverageSelectedKeys(), s.getSelectCount()))
.forEach(System.err::println);
selectors.forEach(ManagedSelector::resetStats);
}
private boolean awaitBarrier(CyclicBarrier barrier)
{
try
{
barrier.await();
return true;
}
catch (Throwable x)
{
return false;
}
}
}