记录一次No buffer space available问题

前言：

服务器的接口服务一直是好的，突然有一天，恩，接口服务不通了，看log，发现了这个错误：

Caused by: java.net.SocketException: No buffer space available (maximum connections reached?): connect
    at sun.nio.ch.Net.connect0(Native Method)
    at sun.nio.ch.Net.connect(Unknown Source)
    at sun.nio.ch.Net.connect(Unknown Source)
    at sun.nio.ch.SocketChannelImpl.connect(Unknown Source)
    at java.nio.channels.SocketChannel.open(Unknown Source)
    at sun.nio.ch.PipeImpl$Initializer$LoopbackConnector.run(Unknown Source)
    ... 36 common frames omitted
2019-07-02 13:10:18 [main] INFO  o.a.c.h.Http11NioProtocol - Pausing ProtocolHandler ["http-nio-8556"]
2019-07-02 13:10:18 [main] ERROR o.a.c.c.Connector - Protocol handler pause failed
java.lang.NullPointerException: null
    at org.apache.tomcat.util.net.AbstractEndpoint.unlockAccept(AbstractEndpoint.java:899)
    at org.apache.tomcat.util.net.AbstractEndpoint.pause(AbstractEndpoint.java:1185)
    at org.apache.coyote.AbstractProtocol.pause(AbstractProtocol.java:612)
    at org.apache.catalina.connector.Connector.pause(Connector.java:944)
    at org.apache.catalina.core.StandardService.stopInternal(StandardService.java:467)
    at org.apache.catalina.util.LifecycleBase.stop(LifecycleBase.java:226)
    at org.apache.catalina.core.StandardServer.stopInternal(StandardServer.java:814)
    at org.apache.catalina.util.LifecycleBase.stop(LifecycleBase.java:226)
    at org.apache.catalina.startup.Tomcat.stop(Tomcat.java:377)
    at org.springframework.boot.web.embedded.tomcat.TomcatWebServer.stopTomcat(TomcatWebServer.java:247)
    at org.springframework.boot.web.embedded.tomcat.TomcatWebServer.stopSilently(TomcatWebServer.java:235)
    at org.springframework.boot.web.embedded.tomcat.TomcatWebServer.start(TomcatWebServer.java:210)
    at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.startWebServer(ServletWebServerApplicationContext.java:300)
    at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.finishRefresh(ServletWebServerApplicationContext.java:162)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:553)
    at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:140)
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:762)
    at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:398)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:330)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1258)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1246)
    at com.winning.platwebservice.DqmsServiceApplication.main(DqmsServiceApplication.java:10)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at org.springframework.boot.loader.MainMethodRunner.run(MainMethodRunner.java:48)
    at org.springframework.boot.loader.Launcher.launch(Launcher.java:87)
    at org.springframework.boot.loader.Launcher.launch(Launcher.java:50)
    at org.springframework.boot.loader.JarLauncher.main(JarLauncher.java:51)

解决思路：

1.看到No buffer space available,字面意思是说缓冲区内存不足，于是开始查机器内存：因为我们是window服务器，发现硬盘还有50G，查看运行内存还有10G，虚拟内存还有5G，应该不是这些问题，排除；

2.通过查看time_wait进程发现，pid为8561的有好多time_wait进行，再查询发现是zabbix_client，联系了部署zabbix_client的同事，能不能先停一下，发现停下后发现tomcat还是无法启动，排除；

3.更换端口，无效；

4.调整部署的xms参数，调小调大，无效；

5.百度，百度告诉我们这个问题要修改注册表信息，要重启，因为服务器部署了很多别人的应用，没有考虑这种办法；

6.重启tomcat时有报错：

Caused by: java.net.BindException: Address already in use: connect
	at sun.nio.ch.Net.connect0(Native Method)
	at sun.nio.ch.Net.connect(Unknown Source)
	at sun.nio.ch.Net.connect(Unknown Source)
	at sun.nio.ch.SocketChannelImpl.connect(Unknown Source)
	at java.nio.channels.SocketChannel.open(Unknown Source)
	at sun.nio.ch.PipeImpl$Initializer$LoopbackConnector.run(Unknown Source)
	... 37 common frames omitted
2019-07-02 13:10:46 [main] INFO  o.a.c.h.Http11NioProtocol - Pausing ProtocolHandler ["http-nio-8556"]
2019-07-02 13:10:46 [main] INFO  o.a.c.c.StandardService - Stopping service [Tomcat]
2019-07-02 13:10:47 [main] INFO  o.a.c.u.LifecycleBase - The stop() method was called on component [StandardServer[-1]] after stop() had already been called. The second call will be ignored.
2019-07-02 13:10:47 [main] INFO  o.a.c.h.Http11NioProtocol - Stopping ProtocolHandler ["http-nio-8556"]
2019-07-02 13:10:47 [main] INFO  o.a.c.h.Http11NioProtocol - Destroying ProtocolHandler ["http-nio-8556"]
2019-07-02 13:10:47 [main] INFO  o.s.b.a.l.ConditionEvaluationReportLoggingListener - 

Error starting ApplicationContext. To display the conditions report re-run your application with 'debug' enabled.
2019-07-02 13:10:47 [main] ERROR o.s.b.d.LoggingFailureAnalysisReporter - 

***************************
APPLICATION FAILED TO START
***************************

Description:

The Tomcat connector configured to listen on port 8556 failed to start. The port may already be in use or the connector may be misconfigured.

　　猜测可能是因为端口被使用情况，可是查询端口发现这个端口没有被使用，而且更换端口也是无效，有一个印象比较深刻的是，我们查询我们自己端口号和其他端口号时，总是有一个5开头的端口被使用（比如说我们系统是8556端口，发现有一个58556端口被使用，查询8561端口，也发现有一个58561端口被使用），后来发现有一个pid是12122的几乎占据了所有5开头的5位数端口号，这是一个java.exe，我们把它杀掉之后，重启tomcat，发现ok了。

总结：

因为这个服务器部署了好多的项目，是测试服务器，同一时间有很多的连接和http请求，达到了window系统的上限，所以需要修改注册表信息重启，或是停掉消耗资源最多的那个应用。