一、前言
前段時間看到一篇不錯的文章《看了這篇你就會手寫RPC框架了》,於是便來了興趣對着實現了一遍,後面覺得還有很多優化的地方便對其進行了改進。
主要改動點如下:
-
除了Java序列化協議,增加了protobuf和kryo序列化協議,配置即用。 -
增加多種負載均衡算法(隨機、輪詢、加權輪詢、平滑加權輪詢),配置即用。 -
客戶端增加本地服務列表緩存,提高性能。 -
修復高併發情況下,netty導致的內存泄漏問題 -
由原來的每個請求建立一次連接,改爲建立TCP長連接,並多次複用。 -
服務端增加線程池提高消息處理能力
二、介紹
RPC,即 Remote Procedure Call(遠程過程調用),調用遠程計算機上的服務,就像調用本地服務一樣。RPC可以很好的解耦系統,如WebService就是一種基於Http協議的RPC。
調用示意圖
總的來說,就如下幾個步驟:
-
客戶端(ServerA)執行遠程方法時就調用client stub傳遞類名、方法名和參數等信息。 -
client stub會將參數等信息序列化爲二進制流的形式,然後通過Sockect發送給服務端(ServerB) -
服務端收到數據包後,server stub 需要進行解析反序列化爲類名、方法名和參數等信息。 -
server stub調用對應的本地方法,並把執行結果返回給客戶端
所以一個RPC框架有如下角色:
服務消費者
遠程方法的調用方,即客戶端。一個服務既可以是消費者也可以是提供者。
服務提供者
遠程服務的提供方,即服務端。一個服務既可以是消費者也可以是提供者。
註冊中心
保存服務提供者的服務地址等信息,一般由zookeeper、redis等實現。
監控運維(可選)
監控接口的響應時間、統計請求數量等,及時發現系統問題併發出告警通知。
三、實現
本RPC框架rpc-spring-boot-starter涉及技術棧如下:
-
使用zookeeper作爲註冊中心 -
使用netty作爲通信框架 -
消息編解碼:protostuff、kryo、java -
spring -
使用SPI來根據配置動態選擇負載均衡算法等
由於代碼過多,這裏只講幾處改動點。
3.1動態負載均衡算法
1.編寫LoadBalance的實現類
2.自定義註解 @LoadBalanceAno
/**
* 負載均衡註解
*/
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface LoadBalanceAno {
String value() default "";
}
/**
* 輪詢算法
*/
@LoadBalanceAno(RpcConstant.BALANCE_ROUND)
public class FullRoundBalance implements LoadBalance {
private static Logger logger = LoggerFactory.getLogger(FullRoundBalance.class);
private volatile int index;
@Override
public synchronized Service chooseOne(List<Service> services) {
// 加鎖防止多線程情況下,index超出services.size()
if (index == services.size()) {
index = 0;
}
return services.get(index++);
}
}
3.新建在resource目錄下META-INF/servers文件夾並創建文件
4.RpcConfig增加配置項loadBalance
/**
* @author 2YSP
* @date 2020/7/26 15:13
*/
@ConfigurationProperties(prefix = "sp.rpc")
public class RpcConfig {
/**
* 服務註冊中心地址
*/
private String registerAddress = "127.0.0.1:2181";
/**
* 服務暴露端口
*/
private Integer serverPort = 9999;
/**
* 服務協議
*/
private String protocol = "java";
/**
* 負載均衡算法
*/
private String loadBalance = "random";
/**
* 權重,默認爲1
*/
private Integer weight = 1;
// 省略getter setter
}
5.在自動配置類RpcAutoConfiguration根據配置選擇對應的算法實現類
/**
* 使用spi匹配符合配置的負載均衡算法
*
* @param name
* @return
*/
private LoadBalance getLoadBalance(String name) {
ServiceLoader<LoadBalance> loader = ServiceLoader.load(LoadBalance.class);
Iterator<LoadBalance> iterator = loader.iterator();
while (iterator.hasNext()) {
LoadBalance loadBalance = iterator.next();
LoadBalanceAno ano = loadBalance.getClass().getAnnotation(LoadBalanceAno.class);
Assert.notNull(ano, "load balance name can not be empty!");
if (name.equals(ano.value())) {
return loadBalance;
}
}
throw new RpcException("invalid load balance config");
}
@Bean
public ClientProxyFactory proxyFactory(@Autowired RpcConfig rpcConfig) {
ClientProxyFactory clientProxyFactory = new ClientProxyFactory();
// 設置服務發現着
clientProxyFactory.setServerDiscovery(new ZookeeperServerDiscovery(rpcConfig.getRegisterAddress()));
// 設置支持的協議
Map<String, MessageProtocol> supportMessageProtocols = buildSupportMessageProtocols();
clientProxyFactory.setSupportMessageProtocols(supportMessageProtocols);
// 設置負載均衡算法
LoadBalance loadBalance = getLoadBalance(rpcConfig.getLoadBalance());
clientProxyFactory.setLoadBalance(loadBalance);
// 設置網絡層實現
clientProxyFactory.setNetClient(new NettyNetClient());
return clientProxyFactory;
}
3.2本地服務列表緩存
使用Map來緩存數據
/**
* 服務發現本地緩存
*/
public class ServerDiscoveryCache {
/**
* key: serviceName
*/
private static final Map<String, List<Service>> SERVER_MAP = new ConcurrentHashMap<>();
/**
* 客戶端注入的遠程服務service class
*/
public static final List<String> SERVICE_CLASS_NAMES = new ArrayList<>();
public static void put(String serviceName, List<Service> serviceList) {
SERVER_MAP.put(serviceName, serviceList);
}
/**
* 去除指定的值
* @param serviceName
* @param service
*/
public static void remove(String serviceName, Service service) {
SERVER_MAP.computeIfPresent(serviceName, (key, value) ->
value.stream().filter(o -> !o.toString().equals(service.toString())).collect(Collectors.toList())
);
}
public static void removeAll(String serviceName) {
SERVER_MAP.remove(serviceName);
}
public static boolean isEmpty(String serviceName) {
return SERVER_MAP.get(serviceName) == null || SERVER_MAP.get(serviceName).size() == 0;
}
public static List<Service> get(String serviceName) {
return SERVER_MAP.get(serviceName);
}
}
ClientProxyFactory,先查本地緩存,緩存沒有再查詢zookeeper。
/**
* 根據服務名獲取可用的服務地址列表
* @param serviceName
* @return
*/
private List<Service> getServiceList(String serviceName) {
List<Service> services;
synchronized (serviceName){
if (ServerDiscoveryCache.isEmpty(serviceName)) {
services = serverDiscovery.findServiceList(serviceName);
if (services == null || services.size() == 0) {
throw new RpcException("No provider available!");
}
ServerDiscoveryCache.put(serviceName, services);
} else {
services = ServerDiscoveryCache.get(serviceName);
}
}
return services;
}
問題: 如果服務端因爲宕機或網絡問題下線了,緩存卻還在就會導致客戶端請求已經不可用的服務端,增加請求失敗率。 **解決方案:**由於服務端註冊的是臨時節點,所以如果服務端下線節點會被移除。只要監聽zookeeper的子節點,如果新增或刪除子節點就直接清空本地緩存即可。
DefaultRpcProcessor
/**
* Rpc處理者,支持服務啓動暴露,自動注入Service
* @author 2YSP
* @date 2020/7/26 14:46
*/
public class DefaultRpcProcessor implements ApplicationListener<ContextRefreshedEvent> {
@Override
public void onApplicationEvent(ContextRefreshedEvent event) {
// Spring啓動完畢過後會收到一個事件通知
if (Objects.isNull(event.getApplicationContext().getParent())){
ApplicationContext context = event.getApplicationContext();
// 開啓服務
startServer(context);
// 注入Service
injectService(context);
}
}
private void injectService(ApplicationContext context) {
String[] names = context.getBeanDefinitionNames();
for(String name : names){
Class<?> clazz = context.getType(name);
if (Objects.isNull(clazz)){
continue;
}
Field[] declaredFields = clazz.getDeclaredFields();
for(Field field : declaredFields){
// 找出標記了InjectService註解的屬性
InjectService injectService = field.getAnnotation(InjectService.class);
if (injectService == null){
continue;
}
Class<?> fieldClass = field.getType();
Object object = context.getBean(name);
field.setAccessible(true);
try {
field.set(object,clientProxyFactory.getProxy(fieldClass));
} catch (IllegalAccessException e) {
e.printStackTrace();
}
// 添加本地服務緩存
ServerDiscoveryCache.SERVICE_CLASS_NAMES.add(fieldClass.getName());
}
}
// 註冊子節點監聽
if (clientProxyFactory.getServerDiscovery() instanceof ZookeeperServerDiscovery){
ZookeeperServerDiscovery serverDiscovery = (ZookeeperServerDiscovery) clientProxyFactory.getServerDiscovery();
ZkClient zkClient = serverDiscovery.getZkClient();
ServerDiscoveryCache.SERVICE_CLASS_NAMES.forEach(name ->{
String servicePath = RpcConstant.ZK_SERVICE_PATH + RpcConstant.PATH_DELIMITER + name + "/service";
zkClient.subscribeChildChanges(servicePath, new ZkChildListenerImpl());
});
logger.info("subscribe service zk node successfully");
}
}
private void startServer(ApplicationContext context) {
...
}
}
ZkChildListenerImpl
/**
* 子節點事件監聽處理類
*/
public class ZkChildListenerImpl implements IZkChildListener {
private static Logger logger = LoggerFactory.getLogger(ZkChildListenerImpl.class);
/**
* 監聽子節點的刪除和新增事件
* @param parentPath /rpc/serviceName/service
* @param childList
* @throws Exception
*/
@Override
public void handleChildChange(String parentPath, List<String> childList) throws Exception {
logger.debug("Child change parentPath:[{}] -- childList:[{}]", parentPath, childList);
// 只要子節點有改動就清空緩存
String[] arr = parentPath.split("/");
ServerDiscoveryCache.removeAll(arr[2]);
}
}
3.3nettyClient支持TCP長連接
這部分的改動最多,先增加新的sendRequest接口。
實現類NettyNetClient
/**
* @author 2YSP
* @date 2020/7/25 20:12
*/
public class NettyNetClient implements NetClient {
private static Logger logger = LoggerFactory.getLogger(NettyNetClient.class);
private static ExecutorService threadPool = new ThreadPoolExecutor(4, 10, 200,
TimeUnit.SECONDS, new LinkedBlockingQueue<>(1000), new ThreadFactoryBuilder()
.setNameFormat("rpcClient-%d")
.build());
private EventLoopGroup loopGroup = new NioEventLoopGroup(4);
/**
* 已連接的服務緩存
* key: 服務地址,格式:ip:port
*/
public static Map<String, SendHandlerV2> connectedServerNodes = new ConcurrentHashMap<>();
@Override
public byte[] sendRequest(byte[] data, Service service) throws InterruptedException {
....
return respData;
}
@Override
public RpcResponse sendRequest(RpcRequest rpcRequest, Service service, MessageProtocol messageProtocol) {
String address = service.getAddress();
synchronized (address) {
if (connectedServerNodes.containsKey(address)) {
SendHandlerV2 handler = connectedServerNodes.get(address);
logger.info("使用現有的連接");
return handler.sendRequest(rpcRequest);
}
String[] addrInfo = address.split(":");
final String serverAddress = addrInfo[0];
final String serverPort = addrInfo[1];
final SendHandlerV2 handler = new SendHandlerV2(messageProtocol, address);
threadPool.submit(() -> {
// 配置客戶端
Bootstrap b = new Bootstrap();
b.group(loopGroup).channel(NioSocketChannel.class)
.option(ChannelOption.TCP_NODELAY, true)
.handler(new ChannelInitializer<SocketChannel>() {
@Override
protected void initChannel(SocketChannel socketChannel) throws Exception {
ChannelPipeline pipeline = socketChannel.pipeline();
pipeline
.addLast(handler);
}
});
// 啓用客戶端連接
ChannelFuture channelFuture = b.connect(serverAddress, Integer.parseInt(serverPort));
channelFuture.addListener(new ChannelFutureListener() {
@Override
public void operationComplete(ChannelFuture channelFuture) throws Exception {
connectedServerNodes.put(address, handler);
}
});
}
);
logger.info("使用新的連接。。。");
return handler.sendRequest(rpcRequest);
}
}
}
每次請求都會調用sendRequest()方法,用線程池異步和服務端創建TCP長連接,連接成功後將SendHandlerV2緩存到ConcurrentHashMap中方便複用,後續請求的請求地址(ip+port)如果在connectedServerNodes中存在則使用connectedServerNodes中的handler處理不再重新建立連接。
SendHandlerV2
/**
* @author 2YSP
* @date 2020/8/19 20:06
*/
public class SendHandlerV2 extends ChannelInboundHandlerAdapter {
private static Logger logger = LoggerFactory.getLogger(SendHandlerV2.class);
/**
* 等待通道建立最大時間
*/
static final int CHANNEL_WAIT_TIME = 4;
/**
* 等待響應最大時間
*/
static final int RESPONSE_WAIT_TIME = 8;
private volatile Channel channel;
private String remoteAddress;
private static Map<String, RpcFuture<RpcResponse>> requestMap = new ConcurrentHashMap<>();
private MessageProtocol messageProtocol;
private CountDownLatch latch = new CountDownLatch(1);
public SendHandlerV2(MessageProtocol messageProtocol,String remoteAddress) {
this.messageProtocol = messageProtocol;
this.remoteAddress = remoteAddress;
}
@Override
public void channelRegistered(ChannelHandlerContext ctx) throws Exception {
this.channel = ctx.channel();
latch.countDown();
}
@Override
public void channelActive(ChannelHandlerContext ctx) throws Exception {
logger.debug("Connect to server successfully:{}", ctx);
}
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
logger.debug("Client reads message:{}", msg);
ByteBuf byteBuf = (ByteBuf) msg;
byte[] resp = new byte[byteBuf.readableBytes()];
byteBuf.readBytes(resp);
// 手動回收
ReferenceCountUtil.release(byteBuf);
RpcResponse response = messageProtocol.unmarshallingResponse(resp);
RpcFuture<RpcResponse> future = requestMap.get(response.getRequestId());
future.setResponse(response);
}
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
cause.printStackTrace();
logger.error("Exception occurred:{}", cause.getMessage());
ctx.close();
}
@Override
public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
ctx.flush();
}
@Override
public void channelInactive(ChannelHandlerContext ctx) throws Exception {
super.channelInactive(ctx);
logger.error("channel inactive with remoteAddress:[{}]",remoteAddress);
NettyNetClient.connectedServerNodes.remove(remoteAddress);
}
@Override
public void userEventTriggered(ChannelHandlerContext ctx, Object evt) throws Exception {
super.userEventTriggered(ctx, evt);
}
public RpcResponse sendRequest(RpcRequest request) {
RpcResponse response;
RpcFuture<RpcResponse> future = new RpcFuture<>();
requestMap.put(request.getRequestId(), future);
try {
byte[] data = messageProtocol.marshallingRequest(request);
ByteBuf reqBuf = Unpooled.buffer(data.length);
reqBuf.writeBytes(data);
if (latch.await(CHANNEL_WAIT_TIME,TimeUnit.SECONDS)){
channel.writeAndFlush(reqBuf);
// 等待響應
response = future.get(RESPONSE_WAIT_TIME, TimeUnit.SECONDS);
}else {
throw new RpcException("establish channel time out");
}
} catch (Exception e) {
throw new RpcException(e.getMessage());
} finally {
requestMap.remove(request.getRequestId());
}
return response;
}
}
RpcFuture
package cn.sp.rpc.client.net;
import java.util.concurrent.*;
/**
* @author 2YSP
* @date 2020/8/19 22:31
*/
public class RpcFuture<T> implements Future<T> {
private T response;
/**
* 因爲請求和響應是一一對應的,所以這裏是1
*/
private CountDownLatch countDownLatch = new CountDownLatch(1);
/**
* Future的請求時間,用於計算Future是否超時
*/
private long beginTime = System.currentTimeMillis();
@Override
public boolean cancel(boolean mayInterruptIfRunning) {
return false;
}
@Override
public boolean isCancelled() {
return false;
}
@Override
public boolean isDone() {
if (response != null) {
return true;
}
return false;
}
/**
* 獲取響應,直到有結果才返回
* @return
* @throws InterruptedException
* @throws ExecutionException
*/
@Override
public T get() throws InterruptedException, ExecutionException {
countDownLatch.await();
return response;
}
@Override
public T get(long timeout, TimeUnit unit) throws InterruptedException, ExecutionException, TimeoutException {
if (countDownLatch.await(timeout,unit)){
return response;
}
return null;
}
public void setResponse(T response) {
this.response = response;
countDownLatch.countDown();
}
public long getBeginTime() {
return beginTime;
}
}
此處邏輯,第一次執行 SendHandlerV2#sendRequest() 時channel需要等待通道建立好之後才能發送請求,所以用CountDownLatch來控制,等待通道建立。 自定義Future+requestMap緩存來實現netty的請求和阻塞等待響應,RpcRequest對象在創建時會生成一個請求的唯一標識requestId,發送請求前先將RpcFuture緩存到requestMap中,key爲requestId,讀取到服務端的響應信息後(channelRead方法),將響應結果放入對應的RpcFuture中。 SendHandlerV2#channelInactive() 方法中,如果連接的服務端異常斷開連接了,則及時清理緩存中對應的serverNode。
四、壓力測試
測試環境:
-
(英特爾)Intel(R) Core(TM) i5-6300HQ CPU @ 2.30GHz 4核 -
windows10家庭版(64位) -
16G內存
1.本地啓動zookeeper 2.本地啓動一個消費者,兩個服務端,輪詢算法 3.使用ab進行壓力測試,4個線程發送10000個請求
ab -c 4 -n 10000 http://localhost:8080/test/user?id=1
測試結果:
從圖片可以看出,10000個請求只用了11s,比之前的130+秒耗時減少了10倍以上。
代碼地址:
https://github.com/2YSP/rpc-spring-boot-starter
https://github.com/2YSP/rpc-example
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