[JMeter]|[JMeter] Can't accept UDP connections java.net.BindException: Address already in use_解决方案 [JMeter]Can'tacceptUDPconnectionsjav

一、问题描述
在Linux服务器（CentOS7系统）中配置并启动JMeter远程监控服务器资源所需的ServerAgent目录下的 startAgent.sh 文件时，系统出现异常提示，如下：

[root@localhost ServerAgent-2.2.3]# ./startAgent.sh INFO2018-12-15 10:29:17.634 [kg.apc.p] (): Binding UDP to 4444 ERROR2018-12-15 10:29:17.686 [kg.apc.p] (): Can't accept UDP connections java.net.BindException: Address already in use at sun.nio.ch.Net.bind0(Native Method) at sun.nio.ch.Net.bind(Net.java:433) at sun.nio.ch.DatagramChannelImpl.bind(DatagramChannelImpl.java:691) at sun.nio.ch.DatagramSocketAdaptor.bind(DatagramSocketAdaptor.java:91) at kg.apc.perfmon.PerfMonWorker.listenUDP(PerfMonWorker.java:144) at kg.apc.perfmon.PerfMonWorker.startAcceptingCommands(PerfMonWorker.java:107) at kg.apc.perfmon.AgentTool.processParams(AgentTool.java:72) at kg.apc.cmdtools.PluginsCMD.processParams(PluginsCMD.java:63) at kg.apc.cmdtools.PluginsCMD.processParams(PluginsCMD.java:23) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)

二、问题分析
从以上抛出的异常信息中提取关键的提示信息：
"Can't accept UDP connections
java.net.BindException: Address already in use"
分析：ServerAgent默认开始的是4444端口，提示“不能接收UDP连接，地址已在使用中”，很可能是该端口已被占用，需要修改为新的端口号再启用or先暂停该端口对应的进程，然后再启用ServerAgent服务

三、解决方案
方式1：先暂停4444端口，再启用ServerAgent服务查询4444端口当前对应的进程：lsof -i:4444

[root@localhost ServerAgent-2.2.3]# lsof -i:4444 COMMANDPID USERFDTYPEDEVICE SIZE/OFF NODE NAME java104069 root18uIPv6 39973580t0UDP *:krb524 java104069 root19uIPv6 39975490t0TCP *:krb524 (LISTEN)

关闭指定PID号码的进程（4444端口进程）：kill -9 104069
此时，亦可正常启用ServerAgent服务，如下：

[root@localhost ServerAgent-2.2.3]# kill -9 104069 [root@localhost ServerAgent-2.2.3]# lsof -i:4444 [root@localhost ServerAgent-2.2.3]# ./startAgent.sh INFO2018-12-15 10:41:51.043 [kg.apc.p] (): Binding UDP to 4444 INFO2018-12-15 10:41:52.059 [kg.apc.p] (): Binding TCP to 4444 INFO2018-12-15 10:41:52.066 [kg.apc.p] (): JP@GC Agent v2.2.3 started

方式2：修改ServerAgent端口，再启用ServerAgent服务 ./startAgent.sh –udp-port 0 –tcp-port xxxx （"xxxx" 为新端口号，如：4567）
./startAgent.sh –udp-port 0 –tcp-port 4567

【[JMeter]|[JMeter] Can't accept UDP connections java.net.BindException: Address already in use_解决方案】参考资料：
[1] JMeter 压测Server Agent无法监控资源问题，PerfMon Metrics Collector报Waiting for sample，Error loading results file - see file log， Can't accept UDP connections java.net.BindException: Address already in use 各种疑难杂症