[DUBBO] Thread pool is EXHAUSTED! 关于duboo provider并发限流的错误及解决方案

最新推荐文章于 2025-09-12 16:52:49 发布

原创最新推荐文章于 2025-09-12 16:52:49 发布 · 1w 阅读

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#java #dubbo #executes参数不正确 #限流问题

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本文探讨了Dubbo中线程池配置不当导致的问题及解决方案，包括如何通过限流参数和调整线程池大小来避免线程耗尽的情况。

问题原因

dubbo推荐也是默认的线程池方案为fix pool固定线程池大小，当请求数大于该线程池大小时，线程池没有可用线程就会出现异常：[DUBBO] Thread pool is EXHAUSTED!

dubbo 的默认线程池大小为100

dubbox（丁丁网）的默认线程池大小为200

解决方案

方案1 在dubbo provider的提供者provider.xml中的每个方法提供限流参数，使所有方法的限流总额不超过协议的线程池总数

<?xml version="1.0" encoding="UTF-8"?>
<!--
 - Copyright 1999-2011 Alibaba Group.
 -
 - Licensed under the Apache License, Version 2.0 (the "License");
 - you may not use this file except in compliance with the License.
 - You may obtain a copy of the License at
 -
 -      http://www.apache.org/licenses/LICENSE-2.0
 -
 - Unless required by applicable law or agreed to in writing, software
 - distributed under the License is distributed on an "AS IS" BASIS,
 - WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 - See the License for the specific language governing permissions and
 - limitations under the License.
-->
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:dubbo="http://code.alibabatech.com/schema/dubbo"
    xmlns:context="http://www.springframework.org/schema/context"
    xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.2.xsd
    http://code.alibabatech.com/schema/dubbo http://code.alibabatech.com/schema/dubbo/dubbo.xsd
    http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.2.xsd">
    
    <!-- 使用dubbo协议，服务在指定端口（配置文件中配置）暴露服务 -->
    <dubbo:protocol id="dubbo" name="${dubbo.protocol.name}" port="${dubbo.protocol.port}" threads="200"/>

    <!-- 创建远程服务代理,声明需要暴露的服务接口 -->

    <!-- 记录投注请求流水-->
    <dubbo:service interface="com.hesiyuan.test.Interface1"
        protocol="dubbo" version="1.0.0" ref="Interface2Service" timeout="300" executes="99"/>
    
    <dubbo:service interface="com.hesiyuan.test.Interface2"
        protocol="dubbo" version="1.0.0" ref="Interface1Service" timeout="300"
executes="99"/>
</beans>

executes参数在Dubbo 2.5.4版本之前，并发完全生效，原因是当前线程总数量的值获取非线程安全导致：

当前线程有200大小，使用中198个线程，目前在短时间内到达5个请求，那么会导致5个请求中2个能够进入线程池获取线程，剩余3个会在一段时间后触发[DUBBO] Thread pool is EXHAUSTED!

真实案例

在做压力测试时，我们设置了线程数200，方法的总executes如上配置所示，设置为199。但是依然出现

[DUBBO] Thread pool is EXHAUSTED!

Failed to invoke method " + invocation.getMethodName() + " in provider " + url + ", cause: The service using threads greater than <dubbo:service executes=\"" + max + "\" /> limited.

duboo在2.5.4的更新中解决，该executes与当前服务总线程数的判断：

原代码中的RpcStatus count（当前运行数获取非线程安全）

@Activate(group = Constants.PROVIDER, value = Constants.EXECUTES_KEY)
public class ExecuteLimitFilter implements Filter {

    public Result invoke(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);
        }
    }

}

更改后使用信号量的代码：

//            if (count.getActive() >= max) {
            /**
             * http://manzhizhen.iteye.com/blog/2386408
             * 通过信号量来做并发控制（即限制能使用的线程数量）
             * 2017-08-21 yizhenqiang
             */
            executesLimit = count.getSemaphore(max);
            if(executesLimit != null && !(acquireResult = executesLimit.tryAcquire())) {
                throw new RpcException("Failed to invoke method " + invocation.getMethodName() + " in provider " + url + ", cause: The service using threads greater than <dubbo:service executes=\"" + max + "\" /> limited.");
            }
        }

Dubbo git修复问题说明：

dubbo-2.5.4

Fixedissues