MyCat：
MyCat的官方网站：
http://www.mycat.org.cn/
下载地址：
https://github.com/MyCATApache/Mycat-download
已经更换为：
http://dl.mycat.io/1.6-RELEASE/
第一步：将Mycat-server-1.4-release-20151019230038-linux.tar.gz上传至服务器
tar -xzvf Mycat-server-1.4-release-20151019230038-linux.tar.gz mv mycat /usr/local
第二步：将压缩包解压缩。建议将mycat放到/usr/local/mycat目录下。
./mycat start
停止：第三步：进入mycat目录的bin目录，启动mycat
./mycat stop
Mycat的默认端口号为：8066mycat 支持的命令{ console | start | stop | restart | status | dump }
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下载新版本的启动的时候会报错：
STATUS | wrapper | 2019/09/27 10:19:53 | --> Wrapper Started as Daemon STATUS | wrapper | 2019/09/27 10:19:53 | Launching a JVM... ERROR | wrapper | 2019/09/27 10:19:53 | JVM exited while loading the application. INFO | jvm 1 | 2019/09/27 10:19:53 | Invalid maximum heap size: -Xmx4G INFO | jvm 1 | 2019/09/27 10:19:53 | The specified size exceeds the maximum representable size. INFO | jvm 1 | 2019/09/27 10:19:53 | Error: Could not create the Java Virtual Machine. INFO | jvm 1 | 2019/09/27 10:19:53 | Error: A fatal exception has occurred. Program will exit. STATUS | wrapper | 2019/09/27 10:19:57 | Launching a JVM... ERROR | wrapper | 2019/09/27 10:19:57 | JVM exited while loading the application. INFO | jvm 2 | 2019/09/27 10:19:57 | Invalid maximum heap size: -Xmx4G INFO | jvm 2 | 2019/09/27 10:19:57 | The specified size exceeds the maximum representable size. INFO | jvm 2 | 2019/09/27 10:19:57 | Error: Could not create the Java Virtual Machine. INFO | jvm 2 | 2019/09/27 10:19:57 | Error: A fatal exception has occurred. Program will exit. STATUS | wrapper | 2019/09/27 10:20:02 | Launching a JVM... ERROR | wrapper | 2019/09/27 10:20:02 | JVM exited while loading the application. INFO | jvm 3 | 2019/09/27 10:20:02 | Invalid maximum heap size: -Xmx4G INFO | jvm 3 | 2019/09/27 10:20:02 | The specified size exceeds the maximum representable size. INFO | jvm 3 | 2019/09/27 10:20:02 | Error: Could not create the Java Virtual Machine. INFO | jvm 3 | 2019/09/27 10:20:02 | Error: A fatal exception has occurred. Program will exit. STATUS | wrapper | 2019/09/27 10:20:06 | Launching a JVM... ERROR | wrapper | 2019/09/27 10:20:06 | JVM exited while loading the application. INFO | jvm 4 | 2019/09/27 10:20:06 | Invalid maximum heap size: -Xmx4G INFO | jvm 4 | 2019/09/27 10:20:06 | The specified size exceeds the maximum representable size. INFO | jvm 4 | 2019/09/27 10:20:06 | Error: Could not create the Java Virtual Machine. INFO | jvm 4 | 2019/09/27 10:20:06 | Error: A fatal exception has occurred. Program will exit. STATUS | wrapper | 2019/09/27 10:20:10 | Launching a JVM... ERROR | wrapper | 2019/09/27 10:20:10 | JVM exited while loading the application. INFO | jvm 5 | 2019/09/27 10:20:10 | Invalid maximum heap size: -Xmx4G INFO | jvm 5 | 2019/09/27 10:20:10 | The specified size exceeds the maximum representable size. INFO | jvm 5 | 2019/09/27 10:20:10 | Error: Could not create the Java Virtual Machine. INFO | jvm 5 | 2019/09/27 10:20:10 | Error: A fatal exception has occurred. Program will exit. FATAL | wrapper | 2019/09/27 10:20:10 | There were 5 failed launches in a row, each lasting less than 300 seconds. Giving up. FATAL | wrapper | 2019/09/27 10:20:10 | There may be a configuration problem: please check the logs. STATUS | wrapper | 2019/09/27 10:20:10 | <-- Wrapper Stopped
大致意思是jvm内存不够，解决方法：
在mycat文件下conf中修改wrapper.conf文件
删除一下两行：在第36,37行（1.6的版本）
wrapper.java.additional.10=-Xmx4G wrapper.java.additional.11=-Xms1G
然后再次启动的时候，还会报错：
STATUS | wrapper | 2019/09/29 23:24:33 | --> Wrapper Started as Daemon STATUS | wrapper | 2019/09/29 23:24:34 | Launching a JVM... ERROR | wrapper | 2019/09/29 23:24:49 | JVM exited while loading the application. INFO | jvm 1 | 2019/09/29 23:24:49 | Error: Exception thrown by the agent : java.net.MalformedURLException: Local host name unknown: java.net.UnknownHostException: cluster-1: cluster-1: Temporary failure in name resolution STATUS | wrapper | 2019/09/29 23:24:53 | Launching a JVM... ERROR | wrapper | 2019/09/29 23:25:08 | JVM exited while loading the application. INFO | jvm 2 | 2019/09/29 23:25:08 | Error: Exception thrown by the agent : java.net.MalformedURLException: Local host name unknown: java.net.UnknownHostException: cluster-1: cluster-1: Temporary failure in name resolution STATUS | wrapper | 2019/09/29 23:25:12 | Launching a JVM... ERROR | wrapper | 2019/09/29 23:25:28 | JVM exited while loading the application. INFO | jvm 3 | 2019/09/29 23:25:28 | Error: Exception thrown by the agent : java.net.MalformedURLException: Local host name unknown: java.net.UnknownHostException: cluster-1: cluster-1: Temporary failure in name resolution STATUS | wrapper | 2019/09/29 23:25:32 | Launching a JVM... ERROR | wrapper | 2019/09/29 23:25:47 | JVM exited while loading the application. INFO | jvm 4 | 2019/09/29 23:25:47 | Error: Exception thrown by the agent : java.net.MalformedURLException: Local host name unknown: java.net.UnknownHostException: cluster-1: cluster-1: Temporary failure in name resolution STATUS | wrapper | 2019/09/29 23:25:51 | Launching a JVM... ERROR | wrapper | 2019/09/29 23:26:06 | JVM exited while loading the application. INFO | jvm 5 | 2019/09/29 23:26:06 | Error: Exception thrown by the agent : java.net.MalformedURLException: Local host name unknown: java.net.UnknownHostException: cluster-1: cluster-1: Temporary failure in name resolution FATAL | wrapper | 2019/09/29 23:26:06 | There were 5 failed launches in a row, each lasting less than 300 seconds. Giving up. FATAL | wrapper | 2019/09/29 23:26:06 | There may be a configuration problem: please check the logs. STATUS | wrapper | 2019/09/29 23:26:06 | <-- Wrapper Stopped
解决方法：
vi /etc/sysconfig/network
追加一行： HOSTNAME=你的主机名
接着修改： vi /etc/hosts
添加这句后面添加 你的主机名
127.0.0.1 localhost.localdomain localhost 你的主机名
然后重新启动。。。。ok