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Dubbo性能调优参数及原理

JAVA架构 1003

前言：

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本文是针对 Dubbo 协议调用的调优指导，详细说明常用调优参数的作用域及源码。

Dubbo调用模型

常用性能调优参数

参数名作用范围默认值说明备注threadsprovider200业务处理线程池大小

iothreadsproviderCPU+1io线程池大小

queuesprovider0

线程池队列大小，当线程池满时，排队等待执行的队列大小，

建议不要设置，当线程程池时应立即失败，

重试其它服务提供机器，而不是排队，除非有特殊需求

connectionsconsumer0

对每个提供者的最大连接数，

rmi、http、hessian等短连接协议表示限制连接数，

Dubbo等长连接协表示建立的长连接个数

Dubbo协议默认共享一个长连接activesconsumer0每服务消费者每服务每方法最大并发调用数0表示不限制acceptesprovider0服务提供方最大可接受连接数0表示不限制executesprovider0服务提供者每服务每方法最大可并行执行请求数0表示不限制

源码及原理分析

>> threads

FixedThreadPool.java

public Executor getExecutor(URL url) {
String name = url.getParameter(Constants.THREAD_NAME_KEY, Constants.DEFAULT_THREAD_NAME);
int threads = url.getParameter(Constants.THREADS_KEY, Constants.DEFAULT_THREADS);
int queues = url.getParameter(Constants.QUEUES_KEY, Constants.DEFAULT_QUEUES);
return new ThreadPoolExecutor(threads, threads, 0, TimeUnit.MILLISECONDS,
queues == 0 ? new SynchronousQueue<Runnable> :
(queues < 0 ? new LinkedBlockingQueue<Runnable> :
new LinkedBlockingQueue<Runnable>(queues)),
new NamedThreadFactory(name, true), new AbortPolicyWithReport(name, url));
}

LimitedThreadPool.java

public Executor getExecutor(URL url) {
String name = url.getParameter(Constants.THREAD_NAME_KEY, Constants.DEFAULT_THREAD_NAME);
int cores = url.getParameter(Constants.CORE_THREADS_KEY, Constants.DEFAULT_CORE_THREADS);
int threads = url.getParameter(Constants.THREADS_KEY, Constants.DEFAULT_THREADS);
int queues = url.getParameter(Constants.QUEUES_KEY, Constants.DEFAULT_QUEUES);
return new ThreadPoolExecutor(cores, threads, Long.MAX_VALUE, TimeUnit.MILLISECONDS,
queues == 0 ? new SynchronousQueue<Runnable> :
(queues < 0 ? new LinkedBlockingQueue<Runnable> :
new LinkedBlockingQueue<Runnable>(queues)),
new NamedThreadFactory(name, true), new AbortPolicyWithReport(name, url));
}

其中，Constants.DEFAULT_QUEUES = 200。threads 参数配置的是业务处理线程池的最大（或核心）线程数。

>> iothreads

NettyServer.java

@Override
protected void doOpen throws Throwable {
NettyHelper.setNettyLoggerFactory;
ExecutorService boss = Executors.newCachedThreadPool(new NamedThreadFactory("NettyServerBoss", true));
ExecutorService worker = Executors.newCachedThreadPool(new NamedThreadFactory("NettyServerWorker", true));
ChannelFactory channelFactory = new NioServerSocketChannelFactory(boss, worker, getUrl.getPositiveParameter(Constants.IO_THREADS_KEY, Constants.DEFAULT_IO_THREADS));
bootstrap = new ServerBootstrap(channelFactory);
final NettyHandler nettyHandler = new NettyHandler(getUrl, this);
channels = nettyHandler.getChannels;
bootstrap.setPipelineFactory(new ChannelPipelineFactory {
public ChannelPipeline getPipeline {
NettyCodecAdapter adapter = new NettyCodecAdapter(getCodec ,getUrl, NettyServer.this);
ChannelPipeline pipeline = Channels.pipeline;
pipeline.addLast("decoder", adapter.getDecoder);
pipeline.addLast("encoder", adapter.getEncoder);
pipeline.addLast("handler", nettyHandler);
return pipeline;
}
});
// bind
channel = bootstrap.bind(getBindAddress);
}

>> queues

分别在 FixedThreadPool.java、LimitedThreadPool.java 和 CachedThreadPool.java 中使用，代码详情见 3.2章节。 由代码可见，默认值为 0，表示使用同步阻塞队列；如果 queues 设置为小于 0 的值，则使用容量为 Integer.MAX_VALUE 的阻塞链表队列；如果为其他值，则使用指定大小的阻塞链表队列。

>> connections

DubboProtocol.java

private ExchangeClient getClients(URL url){
//是否共享连接
boolean service_share_connect = false;
int connections = url.getParameter(Constants.CONNECTIONS_KEY, 0);
//如果connections不配置，则共享连接，否则每服务每连接
if (connections == 0){
service_share_connect = true;
connections = 1;
}
ExchangeClient clients = new ExchangeClient[connections];
for (int i = 0; i < clients.length; i++) {
if (service_share_connect){
clients[i] = getSharedClient(url);
} else {
clients[i] = initClient(url);
}
}
return clients;
}

DubboInvoker.java

@Override
protected Result doInvoke(final Invocation invocation) throws Throwable {
RpcInvocation inv = (RpcInvocation) invocation;
final String methodName = RpcUtils.getMethodName(invocation);
inv.setAttachment(Constants.PATH_KEY, getUrl.getPath);
inv.setAttachment(Constants.VERSION_KEY, version);
ExchangeClient currentClient;
if (clients.length == 1) {
currentClient = clients[0];
} else {
currentClient = clients[index.getAndIncrement() % clients.length];
}
try {
boolean isAsync = RpcUtils.isAsync(getUrl, invocation);
boolean isOneway = RpcUtils.isOneway(getUrl, invocation);
int timeout = getUrl.getMethodParameter(methodName, Constants.TIMEOUT_KEY,Constants.DEFAULT_TIMEOUT);
if (isOneway) {
boolean isSent = getUrl.getMethodParameter(methodName, Constants.SENT_KEY, false);
currentClient.send(inv, isSent);
RpcContext.getContext.setFuture;
return new RpcResult;
} else if (isAsync) {
ResponseFuture future = currentClient.request(inv, timeout) ;
RpcContext.getContext.setFuture(new FutureAdapter<Object>(future));
return new RpcResult;
} else {
RpcContext.getContext.setFuture;
return (Result) currentClient.request(inv, timeout).get;
}
} catch (TimeoutException e) {
throw new RpcException(RpcException.TIMEOUT_EXCEPTION, "Invoke remote method timeout. method: " + invocation.getMethodName + ", provider: " + getUrl + ", cause: " + e.getMessage, e);
} catch (RemotingException e) {
throw new RpcException(RpcException.NETWORK_EXCEPTION, "Failed to invoke remote method: " + invocation.getMethodName + ", provider: " + getUrl + ", cause: " + e.getMessage, e);
}
}

以上可见，默认值为0，表示针对每个 Provider，所有客户端共享一个长连接；否则，建立指定数量的长连接。在调用时，如果有多个长连接，则使用轮询方式获得一个长连接。

>> actives

ActiveLimitFilter.java

public Result invoke(Invoker<?> invoker, Invocation invocation) throws RpcException {
URL url = invoker.getUrl;
String methodName = invocation.getMethodName;
int max = invoker.getUrl.getMethodParameter(methodName, Constants.ACTIVES_KEY, 0);
RpcStatus count = RpcStatus.getStatus(invoker.getUrl, invocation.getMethodName);
if (max > 0) {
long timeout = invoker.getUrl.getMethodParameter(invocation.getMethodName, Constants.TIMEOUT_KEY, 0);
long start = System.currentTimeMillis;
long remain = timeout;
int active = count.getActive;
if (active >= max) {
synchronized (count) {
while ((active = count.getActive) >= max) {
try {
count.wait(remain);
} catch (InterruptedException e) {
}
long elapsed = System.currentTimeMillis - start;
remain = timeout - elapsed;
if (remain <= 0) {
throw new RpcException("Waiting concurrent invoke timeout in client-side for service: "
+ invoker.getInterface.getName + ", method: "
+ invocation.getMethodName + ", elapsed: " + elapsed
+ ", timeout: " + timeout + ". concurrent invokes: " + active
+ ". max concurrent invoke limit: " + max);
}
}
}
}
}
try {
long begin = System.currentTimeMillis;
RpcStatus.beginCount(url, methodName);
try {
Result result = invoker.invoke(invocation);
RpcStatus.endCount(url, methodName, System.currentTimeMillis - begin, true);
return result;
} catch (RuntimeException t) {
RpcStatus.endCount(url, methodName, System.currentTimeMillis - begin, false);
throw t;
}
} finally {
if(max>0){
synchronized (count) {
count.notify;
}
}
}
}

Consumer 调用时，统计服务和方法维度的调用情况，如果并发数超过设置的最大值，则阻塞当前线程，直到前面有请求处理完成。

>> accepts

AbstractServer.java

@Override
public void connected(Channel ch) throws RemotingException {
Collection<Channel> channels = getChannels;
if (accepts > 0 && channels.size > accepts) {
logger.error("Close channel " + ch + ", cause: The server " + ch.getLocalAddress + " connections greater than max config " + accepts);
ch.close;
return;
}
super.connected(ch);
}

当连接数大于最大值时，关闭当前连接。

>> executes

ExecuteLimitFilter.java

public Result invokeOrg(Invoker<?> invoker, Invocation invocation) throws RpcException {
URL url = invoker.getUrl;
String methodName = invocation.getMethodName;
int max = url.getMethodParameter(methodName, Constants.EXECUTES_KEY, 0);
if (max > 0) {
RpcStatus count = RpcStatus.getStatus(url, invocation.getMethodName);
if (count.getActive >= max) {
throw new RpcException("Failed to invoke method " + invocation.getMethodName + " in provider " + url + ", cause: The service using threads greater than <dubbo:service executes=\"" + max + "\" /> limited.");
}
}
long begin = System.currentTimeMillis;
boolean isException = false;
RpcStatus.beginCount(url, methodName);
try {
Result result = invoker.invoke(invocation);
return result;
} catch (Throwable t) {
isException = true;
if(t instanceof RuntimeException) {
throw (RuntimeException) t;
}
else {
throw new RpcException("unexpected exception when ExecuteLimitFilter", t);
}
}
finally {
RpcStatus.endCount(url, methodName, System.currentTimeMillis - begin, isException);
}
}

Provider处理请求时，统计方法维度的调用情况，如果并发数超过设置的最大值，则阻直接抛出异常。

作者：cyfonly

出处：

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