对网络编程来说,最基本的三要素是IO, 协议(编解码),服务器端线程模型。这篇来看看ZooKeeper是如何实现高性能的网络程序。
IO模型
ZooKeeper默认提供了两种网络IO的实现,一个是Java原生的NIO,一个是基于Netty的IO。先从ServerCnxn这个抽象类看起,它表示一个从客户端到服务器端的网络连接。ServerCnxn实现了Stat服务器端统计接口,Watcher接口。 Watcher接口里面定义了KeeperState和EventType这两个枚举类型。
ServerCnxn有两个默认实现类,一个是基于JDK原生NIO的NIOServerCnxn,一个是基于Netty的NettyServerCnxn。
- // ServerCnxn的属性
- public abstract class ServerCnxn implements Stats, Watcher {
- protected abstract ServerStats serverStats();
- protected final Date established = new Date();
- protected final AtomicLong packetsReceived = new AtomicLong();
- protected final AtomicLong packetsSent = new AtomicLong();
- protected long minLatency;
- protected long maxLatency;
- protected String lastOp;
- protected long lastCxid;
- protected long lastZxid;
- protected long lastResponseTime;
- protected long lastLatency;
- protected long count;
- protected long totalLatency;
- }
重点看一下NIOServerCnxn,它处理和客户端的连接。它的唯一构造函数需要4个参数:ZooKeeperServer, SocketChannel, SelectionKey, NIOServerCnxnFactory。NIOServerCnxn本质上是对SocketChannel的封装,它提供了对SocketChannel读写的方法。
- public NIOServerCnxn(ZooKeeperServer zk, SocketChannel sock,
- SelectionKey sk, NIOServerCnxnFactory factory) throws IOException {
- this.zkServer = zk;
- this.sock = sock;
- this.sk = sk;
- this.factory = factory;
- if (this.factory.login != null) {
- this.zooKeeperSaslServer = new ZooKeeperSaslServer(factory.login);
- }
- if (zk != null) {
- outstandingLimit = zk.getGlobalOutstandingLimit();
- }
- sock.socket().setTcpNoDelay(true);
- /* set socket linger to false, so that socket close does not
- * block */
- sock.socket().setSoLinger(false, -1);
- InetAddress addr = ((InetSocketAddress) sock.socket()
- .getRemoteSocketAddress()).getAddress();
- authInfo.add(new Id("ip", addr.getHostAddress()));
- sk.interestOps(SelectionKey.OP_READ);
- }
NIOServerCnxn的核心方法是doIO, 它实现了SelectionKey被Selector选出后,SocketChannel如何进行读写
SocketChannel从客户端读数据的过程:
1. NIOServerCnxc维护了两个读数据的ByteBuffer, 一个是 lenBuffer = ByteBuffer.allocate(4), 4个字节的ByteBuffer,表示是否是4个字符的命令消息,比如ruok, conf这种命令。ByteBuffer incomingBuffer表示用来存放读数据ByteBuffer, 初始状态下incomingBuffer指向lenBuffer
2. SocketChannel先向incomingBuffer写入数据,如果写入的长度小于0就抛异常。如果正常写入,并且incomingBuffer写满了,如果incomingBuffer是指向lenBuffer,表示这次读的是4个字节的长度。
3. readLength方法会判断是否是4字符命令,首先调用checkFourLetterWord来判断是否是4字符命令
4. 在checkFourLetterWord中,如果是4字符命令,就调用对应的线程CommandThread,启动单独的线程去执行对应的命令,具体的如何写会在后面说.
如果不是4字符命令,就会incomingBuffer分配对应长度的ByteBuffer, incomingBuffer = ByteBuffer.allocate(len); 不在指向lenBuffer
5. 如果不是4字符命令,进入到readPayload分支。在readPayload判断incomingBuffer是否满包,如果不是,就尝试读一次SocketChanel。如果这时候满包了,就调用flip方法切换到读模式,如果是第一次读到请求,就进入readConnectRequest,如果不是就进入到readRequest。 最后 incomingBuffer = lenBuffer; 再次指向lenBuffer,读下一个请求。
- void doIO(SelectionKey k) throws InterruptedException {
- try {
- if (isSocketOpen() == false) {
- LOG.warn("trying to do i/o on a null socket for session:0x"
- + Long.toHexString(sessionId));
- return;
- }
- if (k.isReadable()) {
- int rc = sock.read(incomingBuffer);
- if (rc < 0) {
- throw new EndOfStreamException(
- "Unable to read additional data from client sessionid 0x"
- + Long.toHexString(sessionId)
- + ", likely client has closed socket");
- }
- if (incomingBuffer.remaining() == 0) {
- boolean isPayload;
- if (incomingBuffer == lenBuffer) { // start of next request
- incomingBuffer.flip();
- isPayload = readLength(k);
- incomingBuffer.clear();
- } else {
- // continuation
- isPayload = true;
- }
- if (isPayload) { // not the case for 4letterword
- readPayload();
- }
- else {
- // four letter words take care
- // need not do anything else
- return;
- }
- }
- }
- ............
- }
- private boolean readLength(SelectionKey k) throws IOException {
- // Read the length, now get the buffer
- int len = lenBuffer.getInt();
- if (!initialized && checkFourLetterWord(sk, len)) {
- return false;
- }
- if (len < 0 || len > BinaryInputArchive.maxBuffer) {
- throw new IOException("Len error " + len);
- }
- if (zkServer == null) {
- throw new IOException("ZooKeeperServer not running");
- }
- incomingBuffer = ByteBuffer.allocate(len);
- return true;
- }
- private boolean checkFourLetterWord(final SelectionKey k, final int len)
- throws IOException
- {
- // We take advantage of the limited size of the length to look
- // for cmds. They are all 4-bytes which fits inside of an int
- String cmd = cmd2String.get(len);
- if (cmd == null) {
- return false;
- }
- LOG.info("Processing " + cmd + " command from "
- + sock.socket().getRemoteSocketAddress());
- packetReceived();
- /** cancel the selection key to remove the socket handling
- * from selector. This is to prevent netcat problem wherein
- * netcat immediately closes the sending side after sending the
- * commands and still keeps the receiving channel open.
- * The idea is to remove the selectionkey from the selector
- * so that the selector does not notice the closed read on the
- * socket channel and keep the socket alive to write the data to
- * and makes sure to close the socket after its done writing the data
- */
- if (k != null) {
- try {
- k.cancel();
- } catch(Exception e) {
- LOG.error("Error cancelling command selection key ", e);
- }
- }
- final PrintWriter pwriter = new PrintWriter(
- new BufferedWriter(new SendBufferWriter()));
- if (len == ruokCmd) {
- RuokCommand ruok = new RuokCommand(pwriter);
- ruok.start();
- return true;
- } else if (len == getTraceMaskCmd) {
- TraceMaskCommand tmask = new TraceMaskCommand(pwriter);
- tmask.start();
- return true;
- } else if (len == setTraceMaskCmd) {
- int rc = sock.read(incomingBuffer);
- if (rc < 0) {
- throw new IOException("Read error");
- }
- incomingBuffer.flip();
- long traceMask = incomingBuffer.getLong();
- ZooTrace.setTextTraceLevel(traceMask);
- SetTraceMaskCommand setMask = new SetTraceMaskCommand(pwriter, traceMask);
- setMask.start();
- return true;
- } else if (len == enviCmd) {
- EnvCommand env = new EnvCommand(pwriter);
- env.start();
- return true;
- } else if (len == confCmd) {
- ConfCommand ccmd = new ConfCommand(pwriter);
- ccmd.start();
- return true;
- } else if (len == srstCmd) {
- StatResetCommand strst = new StatResetCommand(pwriter);
- strst.start();
- return true;
- } else if (len == crstCmd) {
- CnxnStatResetCommand crst = new CnxnStatResetCommand(pwriter);
- crst.start();
- return true;
- } else if (len == dumpCmd) {
- DumpCommand dump = new DumpCommand(pwriter);
- dump.start();
- return true;
- } else if (len == statCmd || len == srvrCmd) {
- StatCommand stat = new StatCommand(pwriter, len);
- stat.start();
- return true;
- } else if (len == consCmd) {
- ConsCommand cons = new ConsCommand(pwriter);
- cons.start();
- return true;
- } else if (len == wchpCmd || len == wchcCmd || len == wchsCmd) {
- WatchCommand wcmd = new WatchCommand(pwriter, len);
- wcmd.start();
- return true;
- } else if (len == mntrCmd) {
- MonitorCommand mntr = new MonitorCommand(pwriter);
- mntr.start();
- return true;
- } else if (len == isroCmd) {
- IsroCommand isro = new IsroCommand(pwriter);
- isro.start();
- return true;
- }
- return false;
- }
- private void readPayload() throws IOException, InterruptedException {
- if (incomingBuffer.remaining() != 0) { // have we read length bytes?
- int rc = sock.read(incomingBuffer); // sock is non-blocking, so ok
- if (rc < 0) {
- throw new EndOfStreamException(
- "Unable to read additional data from client sessionid 0x"
- + Long.toHexString(sessionId)
- + ", likely client has closed socket");
- }
- }
- if (incomingBuffer.remaining() == 0) { // have we read length bytes?
- packetReceived();
- incomingBuffer.flip();
- if (!initialized) {
- readConnectRequest();
- } else {
- readRequest();
- }
- lenBuffer.clear();
- incomingBuffer = lenBuffer;
- }
- }
NIOServerCnxn写数据的过程如下:
1. 创建一个LinkedBlockingQueue<ByteBuffer>类型的outgoingBuffers来优化写,可以一次写多个ByteBuffer
2. 如果SelectionKey是因为写消息被Selector选中 的,先判断outgoingBuffers的长度是否大于0,如果大于0,就把outgoingBuffers中的ByteBuffer的数据都复制到factory.directBuffer这个直接内存的缓冲区中,如果directBuffer满了或者outgoingBuffers都已经复制到directBuffer了,就调用它的flip方法把它切换到读模式,然后把它的数据写入到SocketChannel中去。
由此可见,每次写的时候,都是从directBuffer写到SocketChannel中去的,利用直接内存优化了写操作。
写完后清理一下outgoingBuffers,把已经写完的ByteBuffer清理掉
3. 如果outgoingBuffers都写完了,就把SocketChannel切换到读模式中,关闭对写标志位的监听。如果没写完,继续监听写请求。
- void doIO(SelectionKey k) throws InterruptedException {
- try {
- if (isSocketOpen() == false) {
- LOG.warn("trying to do i/o on a null socket for session:0x"
- + Long.toHexString(sessionId));
- return;
- }
- .......
- if (k.isWritable()) {
- if (outgoingBuffers.size() > 0) {
- ByteBuffer directBuffer = factory.directBuffer;
- directBuffer.clear();
- for (ByteBuffer b : outgoingBuffers) {
- if (directBuffer.remaining() < b.remaining()) {
- b = (ByteBuffer) b.slice().limit(
- directBuffer.remaining());
- }
- int p = b.position();
- directBuffer.put(b);
- b.position(p);
- if (directBuffer.remaining() == 0) {
- break;
- }
- }
- directBuffer.flip();
- int sent = sock.write(directBuffer);
- ByteBuffer bb;
- // Remove the buffers that we have sent
- while (outgoingBuffers.size() > 0) {
- bb = outgoingBuffers.peek();
- if (bb == ServerCnxnFactory.closeConn) {
- throw new CloseRequestException("close requested");
- }
- int left = bb.remaining() - sent;
- if (left > 0) {
- bb.position(bb.position() + sent);
- break;
- }
- packetSent();
- sent -= bb.remaining();
- outgoingBuffers.remove();
- }
- // ZooLog.logTraceMessage(LOG,
- // ZooLog.CLIENT_DATA_PACKET_TRACE_MASK, "after send,
- // outgoingBuffers.size() = " + outgoingBuffers.size());
- }
- synchronized(this.factory){
- if (outgoingBuffers.size() == 0) {
- if (!initialized
- && (sk.interestOps() & SelectionKey.OP_READ) == 0) {
- throw new CloseRequestException("responded to info probe");
- }
- sk.interestOps(sk.interestOps()
- & (~SelectionKey.OP_WRITE));
- } else {
- sk.interestOps(sk.interestOps()
- | SelectionKey.OP_WRITE);
- }
- }
- }
- } catch (CancelledKeyException e) {
- LOG.warn("Exception causing close of session 0x"
- + Long.toHexString(sessionId)
- + " due to " + e);
- if (LOG.isDebugEnabled()) {
- LOG.debug("CancelledKeyException stack trace", e);
- }
- close();
- } catch (CloseRequestException e) {
- // expecting close to log session closure
- close();
- } catch (EndOfStreamException e) {
- LOG.warn("caught end of stream exception",e); // tell user why
- // expecting close to log session closure
- close();
- } catch (IOException e) {
- LOG.warn("Exception causing close of session 0x"
- + Long.toHexString(sessionId)
- + " due to " + e);
- if (LOG.isDebugEnabled()) {
- LOG.debug("IOException stack trace", e);
- }
- close();
- }
- }
NIOServerCnxn写操作的入口方法有两个,一个是同步IO的sendBufferSync, 一个是NIO的sendBuffer。
1.基于同步IO的 sendBufferSync方法直接把SocketChannel设置为阻塞模式,然后直接写到Socket中去。上面提到的相应4字符命令的场景,就是使用了sendBufferSync的方法,直接写。
2. sendBuffer方法使用了NIO,它主要是因为使用了outgoingBuffers队列来优化写操作,可以一次写多个ByteBuffer。写的时候,先加入到outgoingBuffers,然后设置SelectionKey的写标志位,这样在下次Selector执行select方法时,可以进行写的动作
- void sendBufferSync(ByteBuffer bb) {
- try {
- /* configure socket to be blocking
- * so that we dont have to do write in
- * a tight while loop
- */
- sock.configureBlocking(true);
- if (bb != ServerCnxnFactory.closeConn) {
- if (sock.isOpen()) {
- sock.write(bb);
- }
- packetSent();
- }
- } catch (IOException ie) {
- LOG.error("Error sending data synchronously ", ie);
- }
- }
- public void sendBuffer(ByteBuffer bb) {
- try {
- if (bb != ServerCnxnFactory.closeConn) {
- // We check if write interest here because if it is NOT set,
- // nothing is queued, so we can try to send the buffer right
- // away without waking up the selector
- if ((sk.interestOps() & SelectionKey.OP_WRITE) == 0) {
- try {
- sock.write(bb);
- } catch (IOException e) {
- // we are just doing best effort right now
- }
- }
- // if there is nothing left to send, we are done
- if (bb.remaining() == 0) {
- packetSent();
- return;
- }
- }
- synchronized(this.factory){
- sk.selector().wakeup();
- if (LOG.isTraceEnabled()) {
- LOG.trace("Add a buffer to outgoingBuffers, sk " + sk
- + " is valid: " + sk.isValid());
- }
- outgoingBuffers.add(bb);
- if (sk.isValid()) {
- sk.interestOps(sk.interestOps() | SelectionKey.OP_WRITE);
- }
- }
- } catch(Exception e) {
- LOG.error("Unexpected Exception: ", e);
- }
- }
协议(编解码)
ZooKeeper使用Apache jute来序列化和反序列化Java对象,把Java对象序列化成二进制数据在网络中传播。在上一篇从ZooKeeper源代码看如何实现分布式系统(二)数据的高可用存储 中已经介绍了Apache Jute,这里不再赘述,简单看一下ZooKeeperServer是如何处理收到的数据包的,可以看到如何把二进制的请求序列化成Java对象来使用。
1. 先用ByteBufferInputStream来将incomingBuffer封装成流,然后用Jute的接口读到RequestHeader对象,这个对象实现了Jute的Record接口
2. RequestHeader只有两个属性,xid表示事务id,type表示请求的类型
3. 如果是auth类型的请求,从incomingBuffer中读取数据,反序列化到AuthPacket中,然后调用AuthenticationProvider来进行认证
4.如果是sasl的请求,执行相应的代码
5. 对于其他的事务请求,构造一个Request对象,进入到submitRequest方法去执行相应的事务请求。
- // ZooKeeperServer
- public void processPacket(ServerCnxn cnxn, ByteBuffer incomingBuffer) throws IOException {
- // We have the request, now process and setup for next
- InputStream bais = new ByteBufferInputStream(incomingBuffer);
- BinaryInputArchive bia = BinaryInputArchive.getArchive(bais);
- RequestHeader h = new RequestHeader();
- h.deserialize(bia, "header");
- // Through the magic of byte buffers, txn will not be
- // pointing
- // to the start of the txn
- incomingBuffer = incomingBuffer.slice();
- if (h.getType() == OpCode.auth) {
- LOG.info("got auth packet " + cnxn.getRemoteSocketAddress());
- AuthPacket authPacket = new AuthPacket();
- ByteBufferInputStream.byteBuffer2Record(incomingBuffer, authPacket);
- String scheme = authPacket.getScheme();
- AuthenticationProvider ap = ProviderRegistry.getProvider(scheme);
- Code authReturn = KeeperException.Code.AUTHFAILED;
- if(ap != null) {
- try {
- authReturn = ap.handleAuthentication(cnxn, authPacket.getAuth());
- } catch(RuntimeException e) {
- LOG.warn("Caught runtime exception from AuthenticationProvider: " + scheme + " due to " + e);
- authReturn = KeeperException.Code.AUTHFAILED;
- }
- }
- if (authReturn!= KeeperException.Code.OK) {
- if (ap == null) {
- LOG.warn("No authentication provider for scheme: "
- + scheme + " has "
- + ProviderRegistry.listProviders());
- } else {
- LOG.warn("Authentication failed for scheme: " + scheme);
- }
- // send a response...
- ReplyHeader rh = new ReplyHeader(h.getXid(), 0,
- KeeperException.Code.AUTHFAILED.intValue());
- cnxn.sendResponse(rh, null, null);
- // ... and close connection
- cnxn.sendBuffer(ServerCnxnFactory.closeConn);
- cnxn.disableRecv();
- } else {
- if (LOG.isDebugEnabled()) {
- LOG.debug("Authentication succeeded for scheme: "
- + scheme);
- }
- LOG.info("auth success " + cnxn.getRemoteSocketAddress());
- ReplyHeader rh = new ReplyHeader(h.getXid(), 0,
- KeeperException.Code.OK.intValue());
- cnxn.sendResponse(rh, null, null);
- }
- return;
- } else {
- if (h.getType() == OpCode.sasl) {
- Record rsp = processSasl(incomingBuffer,cnxn);
- ReplyHeader rh = new ReplyHeader(h.getXid(), 0, KeeperException.Code.OK.intValue());
- cnxn.sendResponse(rh,rsp, "response"); // not sure about 3rd arg..what is it?
- }
- else {
- Request si = new Request(cnxn, cnxn.getSessionId(), h.getXid(),
- h.getType(), incomingBuffer, cnxn.getAuthInfo());
- si.setOwner(ServerCnxn.me);
- submitRequest(si);
- }
- }
- cnxn.incrOutstandingRequests(h);
- }
可以看到ZooKeeper的请求分为了两部分,RequestHeader表示消息头,剩余部分表示消息体。消息头标示了消息的类型。
线程模型
ZooKeeper提供了两种服务器端的线程模型,一种是基于原生NIO的reactor模型,一种是基于Netty的reactor模型。我们看一下基于NIO的reactor模型。
NIOServerCnxnFactory封装了Selector对象来做事件分发。NIOServerCnxnFactory本身实现了Runnable接口来作为一个可运行的线程。它还维护了一个线程,来使它本身作为一个单独的线程运行。
1. configure方法创建了一个守护线程,并且创建了ServerSocketChannel,注册到了Selector上去监听ACCEPT事件
2. 维护了一个HashMap,由客户端IP映射到来自该IP的NIOServerCnxn连接对象。
3. start方法启动线程,开始监听端口来响应客户端请求
4. run方法就是reactor模型的EventLoop,Selector每隔1秒执行一次select方法来处理IO请求,并分发到对应的SocketChannel中去。可以看到在分发请求的时候并没有创建新的线程
所以NIOServerCnxnFactory是一个最简单的单线程的reactor模型,由一个线程来进行IO事件的分发,以及IO的读写
- public class NIOServerCnxnFactory extends ServerCnxnFactory implements Runnable {
- ServerSocketChannel ss;
- final Selector selector = Selector.open();
- Thread thread;
- public void configure(InetSocketAddress addr, int maxcc) throws IOException {
- configureSaslLogin();
- thread = new Thread(this, "NIOServerCxn.Factory:" + addr);
- thread.setDaemon(true);
- maxClientCnxns = maxcc;
- this.ss = ServerSocketChannel.open();
- ss.socket().setReuseAddress(true);
- LOG.info("binding to port " + addr);
- ss.socket().bind(addr);
- ss.configureBlocking(false);
- ss.register(selector, SelectionKey.OP_ACCEPT);
- }
- final HashMap<InetAddress, Set<NIOServerCnxn>> ipMap =
- new HashMap<InetAddress, Set<NIOServerCnxn>>( );
- public void start() {
- // ensure thread is started once and only once
- if (thread.getState() == Thread.State.NEW) {
- thread.start();
- }
- }
- private void addCnxn(NIOServerCnxn cnxn) {
- synchronized (cnxns) {
- cnxns.add(cnxn);
- synchronized (ipMap){
- InetAddress addr = cnxn.sock.socket().getInetAddress();
- Set<NIOServerCnxn> s = ipMap.get(addr);
- if (s == null) {
- // in general we will see 1 connection from each
- // host, setting the initial cap to 2 allows us
- // to minimize mem usage in the common case
- // of 1 entry -- we need to set the initial cap
- // to 2 to avoid rehash when the first entry is added
- s = new HashSet<NIOServerCnxn>(2);
- s.add(cnxn);
- ipMap.put(addr,s);
- } else {
- s.add(cnxn);
- }
- }
- }
- }
- public void run() {
- while (!ss.socket().isClosed()) {
- try {
- selector.select(1000);
- Set<SelectionKey> selected;
- synchronized (this) {
- selected = selector.selectedKeys();
- }
- ArrayList<SelectionKey> selectedList = new ArrayList<SelectionKey>(
- selected);
- Collections.shuffle(selectedList);
- for (SelectionKey k : selectedList) {
- if ((k.readyOps() & SelectionKey.OP_ACCEPT) != 0) {
- SocketChannel sc = ((ServerSocketChannel) k
- .channel()).accept();
- InetAddress ia = sc.socket().getInetAddress();
- int cnxncount = getClientCnxnCount(ia);
- if (maxClientCnxns > 0 && cnxncount >= maxClientCnxns){
- LOG.warn("Too many connections from " + ia
- + " - max is " + maxClientCnxns );
- sc.close();
- } else {
- LOG.info("Accepted socket connection from "
- + sc.socket().getRemoteSocketAddress());
- sc.configureBlocking(false);
- SelectionKey sk = sc.register(selector,
- SelectionKey.OP_READ);
- NIOServerCnxn cnxn = createConnection(sc, sk);
- sk.attach(cnxn);
- addCnxn(cnxn);
- }
- } else if ((k.readyOps() & (SelectionKey.OP_READ | SelectionKey.OP_WRITE)) != 0) {
- NIOServerCnxn c = (NIOServerCnxn) k.attachment();
- c.doIO(k);
- } else {
- if (LOG.isDebugEnabled()) {
- LOG.debug("Unexpected ops in select "
- + k.readyOps());
- }
- }
- }
- selected.clear();
- } catch (RuntimeException e) {
- LOG.warn("Ignoring unexpected runtime exception", e);
- } catch (Exception e) {
- LOG.warn("Ignoring exception", e);
- }
- }
- closeAll();
- LOG.info("NIOServerCnxn factory exited run method");
- }
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【压缩包子文件的文件名称列表】: "content_code" 提示我们这个压缩包可能包含了整个项目的源代码,用户可以下载并研究系统是如何利用上述技术实现的。通过查看和分析代码,学习者可以深入理解这些技术在实际项目中...
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这个源代码包很可能包含了使用Java操作Netty、Redis和ZooKeeper的具体实现,包括但不限于Netty服务器的搭建、Redis数据的存取操作、ZooKeeper的客户端接口调用等。通过研究这些源代码,开发者可以学习如何在实际项目...
在实际项目中,开发者可以通过解压`zookeeper-3.4.5`压缩包,了解ZooKeeper的源代码,学习其实现原理,以便更好地运用到自己的分布式系统设计中。 总之,ZooKeeper 3.4.5 在服务治理和分布式部署中的作用不可忽视,...
这些源代码可能涵盖了业务逻辑、数据访问、服务接口定义、配置文件等多个方面,开发者可以通过阅读和学习这些源码,了解和掌握分布式系统的设计理念和实现细节。 总的来说,ylf分布式商城系统结合了Java Web开发的...
总的来说,这个压缩包提供了一个绝佳的学习资源,对于想深入了解网络编程、数据存储和分布式协调的开发者来说,Netty、Redis和Zookeeper的源代码是宝贵的参考资料。通过研究这些源码,你可以提升自己的技能,更好地...
文件“content_code”可能包含了整个系统的源代码,包括Spring Boot后端服务代码、Dubbo接口定义、Zookeeper配置、Redis连接代码、MySQL数据库脚本、Vue前端项目代码等。这些代码遵循良好的编程规范,经过严格的测试...
分布式秒杀系统是一种在高并发环境下处理大量用户请求的技术,常用于电商平台的限时...这涉及到如限流算法(如漏桶、令牌桶)、分布式事务处理、数据一致性保证等多个高级主题,是理解分布式系统设计和实践的重要案例。
分布式框架资源专题资料涵盖了一系列关于分布式系统、Zookeeper、云原生以及Netty网络库的深入讲解。...这些内容对于想要在IT领域深入发展,特别是涉及分布式系统架构和高性能网络编程的开发者来说,都是宝贵的资源。
后来Google发表了GFS和MapReduce的论文,为Nutch提供了启发,并最终Nutch开发出了NDFS和MapReduce的开源实现,成为了非常优秀的分布式系统基础架构。 开源项目如Hadoop、HBase、ZooKeeper等,都是云计算和分布式...
> + RPC在微服务、分布式系统、Web服务器方面应用太广泛了,需要对底层通信过程有基本认识 > + Nignx、Hadoop、K8s、Tensorflow等系统或软件的底层源码大多是关于RPC的 > + 可以更加熟悉地使用已有的RPC框架,甚至...
同时,通过Netty的高性能网络编程能力,可以优化RPC通信过程,提升服务调用的效率。http和https则用于构建Web接口,允许客户端通过HTTP请求与服务端进行交互,而https确保了这些交互的安全性。 【标签】"dubbo ...
在提供的`content_code`压缩包中,可能包含了上述技术的源代码示例,这为学习和理解这些技术提供了实际的操作素材。对于初学者来说,可以通过阅读和运行这些代码来加深对分布式系统架构的理解;对于开发者来说,这些...
Golang以其高效的性能、内置的并发支持和内存安全特性,成为了构建高性能分布式系统的理想选择。其轻量级的goroutine和channel机制使得编写并发程序变得简单,同时,静态类型的编译语言特性保证了代码的稳定性和可...
Apache ZooKeeper 是一个分布式协调服务,它为分布式应用程序提供了一个高度可用、高性能的框架,用于管理命名空间、配置信息和同步服务。Zookeeper 的核心概念是基于节点(ZNode)的树形数据结构,允许各个分布式...
分布式锁是一种在分布式系统中实现同步访问资源的关键技术。它允许多个节点在同一时间对共享资源进行互斥访问,确保在高并发环境下数据的一致性和完整性。在这个“分布式锁简单实现”项目中,开发者提供了一个基本的...
书中的源代码可能涉及以上这些中间件技术的具体实现和应用场景,通过阅读和理解这些代码,读者可以深入学习Java中间件技术的工作原理,并提升实际开发能力。对于想从事Java后端开发或者对Java中间件感兴趣的开发者来...
Node.js是一种流行的JavaScript运行环境,常用于构建高性能的网络应用。Zookeeper是Apache的一个分布式协调服务,它提供了诸如配置管理、命名服务、分布式同步等功能,对于实现服务的高可用性至关重要。Thrift则是一...
Dubbo是阿里巴巴开源的高性能服务框架,它提供了服务注册、发现、调用、负载均衡等功能,使得多个微服务能够相互通信。而Zookeeper则作为一个协调工具,用于存储和管理Dubbo服务的元数据,确保服务的高可用性和一致...