mycat学习系列3:常见错误

1. 报错信息:Unable to start JVM: No such file or directory

```
STATUS | wrapper  | 2021/04/06 09:17:37 | --> Wrapper Started as Daemon
STATUS | wrapper  | 2021/04/06 09:17:37 | Launching a JVM...
ERROR  | wrapper  | 2021/04/06 09:17:37 | Unable to start JVM: No such file or directory (2)
ERROR  | wrapper  | 2021/04/06 09:17:37 | JVM exited while loading the application.
STATUS | wrapper  | 2021/04/06 09:17:41 | Launching a JVM...
ERROR  | wrapper  | 2021/04/06 09:17:41 | Unable to start JVM: No such file or directory (2)
ERROR  | wrapper  | 2021/04/06 09:17:41 | JVM exited while loading the application.
STATUS | wrapper  | 2021/04/06 09:17:45 | Launching a JVM...
ERROR  | wrapper  | 2021/04/06 09:17:45 | Unable to start JVM: No such file or directory (2)
ERROR  | wrapper  | 2021/04/06 09:17:45 | JVM exited while loading the application.
STATUS | wrapper  | 2021/04/06 09:17:49 | Launching a JVM...
ERROR  | wrapper  | 2021/04/06 09:17:49 | Unable to start JVM: No such file or directory (2)
ERROR  | wrapper  | 2021/04/06 09:17:49 | JVM exited while loading the application.
STATUS | wrapper  | 2021/04/06 09:17:53 | Launching a JVM...
ERROR  | wrapper  | 2021/04/06 09:17:53 | Unable to start JVM: No such file or directory (2)
ERROR  | wrapper  | 2021/04/06 09:17:53 | JVM exited while loading the application.
FATAL  | wrapper  | 2021/04/06 09:17:53 | There were 5 failed launches in a row, each lasting less than 300 seconds.  Giving up.
FATAL  | wrapper  | 2021/04/06 09:17:53 |   There may be a configuration problem: please check the logs.
STATUS | wrapper  | 2021/04/06 09:17:53 | <-- Wrapper Stopped
```

• 原因：原因可能是JVM参数没有配置或者配置错误；
• 解决方法：

  在mycat/conf/wrapper.conf 下增加：
  wrapper.java.command=java安装目录/bin/java
  例如：wrapper.java.command=/usr/local/software/jdk1.8.0_271/bin/java
  

  
• 参考文档：https://blog.youkuaiyun.com/helloxiaozhe/article/details/81603184