springboot项目部署后项目启动慢

说明

最近部署一个项目到centOS上时，项目启动运行，中间会卡住一段时间，将近2,3分钟。看日志没有报错。同样的包，在另外一台机子部署后启动又是正常的。

排查

百度了一圈。网上大部份都说random的原因, 我都照着改了，但是，依然很慢。
于是去问我们部门大大牛；大牛说你用jstack看一下日志了吗？？？我：…
没用过jstack调试工具；于是，又开始漫长的度娘了。

jstack调试

1. 在程序启动之后，立即执行：

ps -aux|grep 程序名称

得到进程pid；

2. 然后执行jstack命令，监控jvm状态：

jstack -l 进程id

jstack的日志大致如下：
卡住的时候关键log是一下这一段：

"main" #1 prio=5 os_prio=0 tid=0x00007f399000c800 nid=0x276a6 runnable [0x00007f39961e1000]
  java.lang.Thread.State: RUNNABLE
    at java.net.Inet6AddressImpl.lookupAllHostAddr(Native Method)
    at java.net.InetAddress$2.lookupAllHostAddr(InetAddress.java:929)
    at java.net.InetAddress.getAddressesFromNameService(InetAddress.java:1324)
    at java.net.InetAddress.getLocalHost(InetAddress.java:1501)
    - locked <0x00000000fd466af8> (a java.lang.Object)
    at sun.management.VMManagementImpl.getVmId(VMManagementImpl.java:140)
    at sun.management.RuntimeImpl.getName(RuntimeImpl.java:59)
    at org.springframework.boot.system.ApplicationPid.getPid(ApplicationPid.java:54)
    at org.springframework.boot.system.ApplicationPid.<init>(ApplicationPid.java:45)
    at org.springframework.boot.logging.LoggingSystemProperties.apply(LoggingSystemProperties.java:123)
    at org.springframework.boot.logging.AbstractLoggingSystem.applySystemProperties(AbstractLoggingSystem.java:177)
    at org.springframework.boot.logging.Slf4JLoggingSystem.loadConfiguration(Slf4JLoggingSystem.java:61)
    at org.springframework.boot.logging.logback.LogbackLoggingSystem.loadConfiguration(LogbackLoggingSystem.java:151)
    at org.springframework.boot.logging.AbstractLoggingSystem.initializeWithConventions(AbstractLoggingSystem.java:80)
    at org.springframework.boot.logging.AbstractLoggingSystem.initialize(AbstractLoggingSystem.java:60)
    at org.springframework.boot.logging.logback.LogbackLoggingSystem.initialize(LogbackLoggingSystem.java:118)
    at org.springframework.boot.context.logging.LoggingApplicationListener.initializeSystem(LoggingApplicationListener.java:313)
    at org.springframework.boot.context.logging.LoggingApplicationListener.initialize(LoggingApplicationListener.java:288)
    at org.springframework.boot.context.logging.LoggingApplicationListener.onApplicationEnvironmentPreparedEvent(LoggingApplicationListener.java:246)
    at org.springframework.boot.context.logging.LoggingApplicationListener.onApplicationEvent(LoggingApplicationListener.java:223)
    at org.springframework.context.event.SimpleApplicationEventMulticaster.doInvokeListener(SimpleApplicationEventMulticaster.java:172)
    at org.springframework.context.event.SimpleApplicationEventMulticaster.invokeListener(SimpleApplicationEventMulticaster.java:165)
    at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:139)
    at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:127)
    at org.springframework.boot.context.event.EventPublishingRunListener.environmentPrepared(EventPublishingRunListener.java:76)
    at org.springframework.boot.SpringApplicationRunListeners.environmentPrepared(SpringApplicationRunListeners.java:53)
    at org.springframework.boot.SpringApplication.prepareEnvironment(SpringApplication.java:345)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:308)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1226)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1215)
    at ctsi.riverchief.eureka.EurekaApplication.main(EurekaApplication.java:12)


   Locked ownable synchronizers:
    - None


"VM Thread" os_prio=0 tid=0x00007f3990256800 nid=0x276bb runnable

这个错误的原因是因为hosts和hostname不一致导致的；

解决方法

1. 查看本机的hostname：

[zjsl@host-192-168-* etc]$ hostname

2. 查看/etc/hosts文件内容：

[zjsl@host-192-168-* etc]$ cat /etc/hosts

这里就发现hosts文件真的没有配置本机的hostname映射；

3. 往hosts里面添加一行到本机的hostname映射（需要root权限）

vi /etc/hosts

4. 保存后，重启网络：

service network restart

重试项目启动，问题解决！！！

参考：Centos 启动Spring boot项目慢的原因