[英]Connection refusal on Java7 async NIO2 server
I have written a async socketserver using java 7 nio2. 我使用java 7 nio2编写了一个异步socketserver。
Here is a snipper of the Server. 这是服务器的一个片段。
public class AsyncJava7Server implements Runnable, CounterProtocol, CounterServer{
private int port = 0;
private AsynchronousChannelGroup group;
public AsyncJava7Server(int port) throws IOException, InterruptedException, ExecutionException {
this.port = port;
}
public void run() {
try {
String localhostname = java.net.InetAddress.getLocalHost().getHostName();
group = AsynchronousChannelGroup.withThreadPool(
Executors.newCachedThreadPool(new NamedThreadFactory("Channel_Group_Thread")));
// open a server channel and bind to a free address, then accept a connection
final AsynchronousServerSocketChannel asyncServerSocketChannel =
AsynchronousServerSocketChannel.open(group).bind(
new InetSocketAddress(localhostname, port));
asyncServerSocketChannel.accept(null,
new CompletionHandler <AsynchronousSocketChannel, Object>() {
@Override
public void completed(final AsynchronousSocketChannel asyncSocketChannel,
Object attachment) {
// Invoke simple handle accept code - only takes about 10 milliseconds.
handleAccept(asyncSocketChannel);
asyncServerSocketChannel.accept(null, this);
}
@Override
public void failed(Throwable exc, Object attachment) {
System.out.println("***********" + exc + " statement=" + attachment);
}
});
and here is a snippet of the client code which tries to connect... 这是一个试图连接的客户端代码片段
public class AsyncJava7Client implements CounterProtocol, CounterClientBridge {
AsynchronousSocketChannel asyncSocketChannel;
private String serverName= null;
private int port;
private String clientName;
public AsyncJava7Client(String clientName, String serverName, int port) throws IOException {
this.clientName = clientName;
this.serverName = serverName;
this.port = port;
}
private void connectToServer() {
Future<Void> connectFuture = null;
try {
log("Opening client async channel...");
asyncSocketChannel = AsynchronousSocketChannel.open();
// Connecting to server
connectFuture = asyncSocketChannel.connect(new InetSocketAddress("Alex-PC", 9999));
} catch (Exception ex) {
ex.printStackTrace();
throw new RuntimeException(ex);
}
// open a new socket channel and connect to the server
long beginTime = 0;
try {
// You have two seconds to connect. This will throw exception if server is not there.
beginTime = System.currentTimeMillis();
Void connectVoid = connectFuture.get(15, TimeUnit.SECONDS);
} catch (Exception ex) {
//EXCEPTIONS THROWN HERE AFTER ABOUT 150 CLIENTS
long endTime = System.currentTimeMillis();
long timeTaken = endTime - beginTime;
log("************* TIME TAKEN=" + timeTaken);
ex.printStackTrace();
throw new RuntimeException(ex);
}
}
I have a test which fires off clients. 我有一个测试可以解雇客户。
@Test
public void testManyClientsAtSametime() throws Exception {
int clientsize = 150;
ScheduledThreadPoolExecutor executor =
(ScheduledThreadPoolExecutor) Executors.newScheduledThreadPool(clientsize + 1,
new NamedThreadFactory("Test_Thread"));
AsyncJava7Server asyncJava7Server = startServer();
List<AsyncJava7Client> clients = new ArrayList<AsyncJava7Client>();
List<Future<String>> results = new ArrayList<Future<String>>();
for (int i = 0; i < clientsize; i++) {
// Now start a client
final AsyncJava7Client client =
new AsyncJava7Client("client" + i, InetAddress.getLocalHost().getHostName(), 9999);
clients.add(client);
}
long beginTime = System.currentTimeMillis();
Random random = new Random();
for (final AsyncJava7Client client: clients) {
Callable<String> callable = new Callable<String>() {
public String call() {
...
... invoke APIs to connect client to server
...
return counterValue;
}
};
long delay = random.nextLong() % 10000; // somewhere between 0 and 10 seconds.
Future<String> startClientFuture = executor.schedule(callable, delay, TimeUnit.MILLISECONDS);
results.add(startClientFuture);
}
It works super for about 100 clients. 它适用于大约100个客户。 At about 140+ I get a load of exceptions in the client - when it tries to connect.
在大约140+时,我在客户端遇到大量异常 - 当它尝试连接时。 The exception is: java.util.concurrent.ExecutionException: java.io.IOException: The remote computer refused the network connection.
例外情况是:java.util.concurrent.ExecutionException:java.io.IOException:远程计算机拒绝网络连接。
My test is on a single laptop running windows 7. When it bombs out I check the TCP connections and there about 500 - 600 connections -that's ok. 我的测试是在一台运行Windows 7的笔记本电脑上。当它轰炸时,我检查TCP连接,那里有大约500 - 600个连接 - 这没关系。 AS I have similiar JDK 1.0 java.net socket programs that can handle 4,000 TCP connections.
我有类似的JDK 1.0 java.net套接字程序,可以处理4,000个TCP连接。
No exceptions or anything dodgy looking in server. 在服务器中没有例外或任何狡猾的东西。
So I am at a loss as to what could be wrong here. 所以我不知道这里可能出现什么问题。 any ideas?
有任何想法吗?
Try using the form of bind
that accepts a backlog limit and set that to a higher number. 尝试使用接受积压限制的
bind
形式并将其设置为更高的数字。 For example: 例如:
final AsynchronousServerSocketChannel asyncServerSocketChannel =
AsynchronousServerSocketChannel.open(group).bind(
new InetSocketAddress(localhostname, port), 1000);
I don't know what the win7 implementation limit is by default but can be a cause of refused connections. 我不知道默认情况下win7实现限制是什么,但可能是拒绝连接的原因。
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