【发布时间】：2010-09-13 19:42:15
【问题描述】：
您好，我一直在尝试查找此内存泄漏，但没有成功。
我拥有的是一个服务器，它为 Flash 客户端安全接受请求提供服务。它只发送一个数据包，但有能力容纳超过 10,000 个并发连接？如果也有的话，可能是 65,534。
无论如何，在 24 小时内为大约 210,000 多个用户提供服务后，内存使用量从 12,000 MB 增加到了 74,000 MB。我认为它会稳定下来并继续思考也许它的一些东西已经解包注册并会被重新使用。但是 48 小时后它达到了 90 MB，按照这个速度，我必须每 2 天重新启动一次服务器以防止 OutOfMemoryException（还没有得到它，但我知道我只需 300 MB 的内存就可以得到它)。
无论如何，如果有人有时间并愿意帮助我，我将非常感激，这里是来源。
import java.io.IOException;
import java.net.InetAddress;
import java.net.InetSocketAddress;
import java.net.Socket;
import java.nio.ByteBuffer;
import java.nio.charset.Charset;
import java.nio.charset.CharsetDecoder;
import java.nio.charset.CodingErrorAction;
import java.nio.channels.CancelledKeyException;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.nio.channels.spi.SelectorProvider;
import java.util.*;
public class PolicyServer implements Runnable {
public static final String POLICY_REQUEST = "<policy-file-request/>";
public static final String POLICY_XML =
"<?xml version=\"1.0\"?>"
+ "<cross-domain-policy>"
+ "<allow-access-from domain=\"*\" to-ports=\"*\" />"
+ "</cross-domain-policy>"
+ (char)0;
// The host:port combination to listen on
private InetAddress hostAddress;
private int port;
// The channel on which we'll accept connections
private ServerSocketChannel serverChannel;
// The selector we'll be monitoring
private Selector selector;
// The buffer into which we'll read data when it's available
private ByteBuffer readBuffer = ByteBuffer.allocate(255);
// This decodes raw bytes into ascii data.
private CharsetDecoder asciiDecoder;
// A list of PendingChange instances
private List<ChangeRequest> pendingChanges = new LinkedList<ChangeRequest>();
// Maps a SocketChannel to a list of ByteBuffer instances
private Map<SocketChannel, List<ByteBuffer>> pendingData = new HashMap<SocketChannel, List<ByteBuffer>>();
public PolicyServer(InetAddress hostAddress, int port) throws IOException {
this.hostAddress = hostAddress;
this.port = port;
this.selector = this.initSelector();
this.asciiDecoder = Charset.forName("US-ASCII").newDecoder().onMalformedInput(
CodingErrorAction.REPLACE).onUnmappableCharacter(
CodingErrorAction.REPLACE);
}
public void send(SocketChannel socket, byte[] data) {
synchronized (this.pendingChanges) {
// Indicate we want the interest ops set changed
this.pendingChanges.add(new ChangeRequest(socket, ChangeRequest.CHANGEOPS, SelectionKey.OP_WRITE));
// And queue the data we want written
synchronized (this.pendingData) {
List<ByteBuffer> queue = (List<ByteBuffer>) this.pendingData.get(socket);
if (queue == null) {
queue = new ArrayList<ByteBuffer>();
this.pendingData.put(socket, queue);
}
queue.add(ByteBuffer.wrap(data));
}
}
// Finally, wake up our selecting thread so it can make the required changes
this.selector.wakeup();
}
public void run() {
while (true) {
try {
// Process any pending changes
synchronized (this.pendingChanges) {
Iterator changes = this.pendingChanges.iterator();
while (changes.hasNext()) {
ChangeRequest change = (ChangeRequest) changes.next();
if(change == null) continue;
switch (change.type) {
case ChangeRequest.CHANGEOPS:
SelectionKey key = change.socket.keyFor(this.selector);
try {
if(key!=null)
key.interestOps(change.ops);
} catch(Exception ex) {
if (key!=null)
key.cancel();
}
}
}
this.pendingChanges.clear();
}
// Wait for an event one of the registered channels
this.selector.select();
// Iterate over the set of keys for which events are available
Iterator selectedKeys = this.selector.selectedKeys().iterator();
while (selectedKeys.hasNext()) {
SelectionKey key = (SelectionKey) selectedKeys.next();
selectedKeys.remove();
if (!key.isValid()) {
continue;
}
// Check what event is available and deal with it
if (key.isAcceptable()) {
this.accept(key);
} else if (key.isReadable()) {
this.read(key);
} else if (key.isWritable()) {
this.write(key);
}
}
} catch (Exception e) {
e.printStackTrace();
}
}
}
private void accept(SelectionKey key) throws IOException {
// For an accept to be pending the channel must be a server socket channel.
ServerSocketChannel serverSocketChannel = (ServerSocketChannel) key.channel();
// Accept the connection and make it non-blocking
SocketChannel socketChannel = serverSocketChannel.accept();
Socket socket = socketChannel.socket();
socketChannel.configureBlocking(false);
// Register the new SocketChannel with our Selector, indicating
// we'd like to be notified when there's data waiting to be read
// also contains a attachment of a new StringBuffer (for storing imcomplete/multi packets)
socketChannel.register(this.selector, SelectionKey.OP_READ, new StringBuffer());
}
private void read(SelectionKey key) throws IOException {
SocketChannel socketChannel = (SocketChannel) key.channel();
// Clear out our read buffer so it's ready for new data
this.readBuffer.clear();
// Attempt to read off the channel
int numRead;
try {
numRead = socketChannel.read(this.readBuffer);
} catch (IOException e) {
// The remote forcibly closed the connection, cancel
// the selection key and close the channel.
key.cancel();
socketChannel.close();
return;
}
if (numRead == -1) {
// Remote entity shut the socket down cleanly. Do the
// same from our end and cancel the channel.
key.channel().close();
key.cancel();
return;
}
// Grab the StringBuffer we stored as the attachment
StringBuffer sb = (StringBuffer)key.attachment();
// Flips the readBuffer by setting the current position of
// packet stream to beginning.
// Append the data to the attachment StringBuffer
this.readBuffer.flip();
sb.append(this.asciiDecoder.decode(this.readBuffer).toString());
this.readBuffer.clear();
// Get the policy request as complete packet
if(sb.indexOf("\0") != -1) {
String packets = sb.substring(0, sb.lastIndexOf("\0")+1);
sb.delete(0, sb.lastIndexOf("\0")+1);
if(packets.indexOf(POLICY_REQUEST) != -1)
send(socketChannel, POLICY_XML.getBytes());
}
}
private void write(SelectionKey key) throws IOException {
SocketChannel socketChannel = (SocketChannel) key.channel();
synchronized (this.pendingData) {
List queue = (List) this.pendingData.get(socketChannel);
// Write until there's not more data ...
while (!queue.isEmpty()) {
ByteBuffer buf = (ByteBuffer) queue.get(0);
try {
socketChannel.write(buf);
if (buf.remaining() > 0) {
// ... or the socket's buffer fills up
break;
}
} catch(IOException e) {
// The remote forcibly closed the connection, cancel
// the selection key and close the channel.
key.cancel();
socketChannel.close();
return;
}
queue.remove(0);
}
if (queue.isEmpty()) {
// We wrote away all data, so we're no longer interested
// in writing on this socket. Switch back to waiting for
// data.
try {
if (key!=null)
key.interestOps(SelectionKey.OP_READ);
} catch(Exception ex) {
if (key!=null)
key.cancel();
}
}
}
}
private Selector initSelector() throws IOException {
// Create a new selector
Selector socketSelector = SelectorProvider.provider().openSelector();
// Create a new non-blocking server socket channel
this.serverChannel = ServerSocketChannel.open();
serverChannel.configureBlocking(false);
// Bind the server socket to the specified address and port
InetSocketAddress isa = new InetSocketAddress(this.hostAddress, this.port);
serverChannel.socket().bind(isa);
// Register the server socket channel, indicating an interest in
// accepting new connections
serverChannel.register(socketSelector, SelectionKey.OP_ACCEPT);
return socketSelector;
}
public static void main(String[] args) {
try {
new Thread(new PolicyServer(null, 5556)).start();
} catch (IOException e) {
e.printStackTrace();
}
}
}
这里是 ChangeRequest 类
import java.nio.channels.SocketChannel;
public class ChangeRequest {
public static final int REGISTER = 1;
public static final int CHANGEOPS = 2;
public SocketChannel socket;
public int type;
public int ops;
public ChangeRequest(SocketChannel socket, int type, int ops) {
this.socket = socket;
this.type = type;
this.ops = ops;
}
}
【问题讨论】：
-
您尝试过探查器吗？它们非常适合跟踪对 GC 根的引用。
-
（我一直不明白如何使用这些分析器似乎太高级但我会尝试）
标签： java memory memory-leaks