MQTT研究之EMQ：【EMQX使用中的一些问题记录（3）】

EMQX功能强大，但是帮助信息或者可用资料的确有限，遇到个问题，比较难找到处理的头绪，今天，我要记录的是，使用中出现EMQX宕机，但是呢，启动也启动不了。 今天记录的内容，就以操作EMQX 3.2.3的版本来说吧。

你可能看到有下面的信息：

[root@tkwh-kfcs-app3 emqx]# emqx start
emqx v3.2.3 is started successfully!

但是呢，你查看状态，又会看到下面的内容：

[root@tkwh-kfcs-app3 emqx]# emqx_ctl status
Node 'emqx@10.95.200.13' not responding to pings

这个是什么情况呢？其实就是EMQX启动异常了，然后又shutdown了，看看日志，在/var/log/emqx下面的 erlang.log.1 文件里面可以找到些许的信息。

       =====
       ===== LOGGING STARTED Fri Oct  :: CST
       =====
       Exec: /usr/lib/emqx/erts-10.3/bin/erlexec -boot /usr/lib/emqx/releases/v3.2.3/emqx -mode embedded -boot_var ERTS_LIB_DIR /usr/lib/emqx/erts-10.3/../lib -mnesia dir "/var/lib/emqx/mnesia/emqx@10.95.200.13" -config /var/lib/emqx/c
        onfigs/app.2019.10.25.10.55.38.config -args_file /var/lib/emqx/configs/vm.2019.10.25.10.55.38.args -vm_args /var/lib/emqx/configs/vm.2019.10.25.10.55.38.args -- console^M
       Root: /usr/lib/emqx^M
       /usr/lib/emqx^M
       Erlang/OTP  [erts-10.3] [source] [-bit] [smp::] [ds:::] [async-threads:] [hipe]^M
       ^M
      -- ::43.487 [info] event=server_setup_successfully driver=tcp socket="#Port<0.8>"^M
      -- ::43.488 [info] event=start^M
      Starting emqx on node emqx@10.95.200.13^M
      -- ::43.562 [info] Ekka(Membership): Node emqx@10.95.200.22 up^M
      -- ::43.580 [notice] application: emqx^M
          exited: {bad_return,^M
                   {{emqx_app,start,[normal,[]]},^M
                    {'EXIT',^M
                     {{badmatch,^M
                       {error,^M
                        {shutdown,^M
                         {failed_to_start_child,emqx_router_sup,^M
                          {shutdown,^M
                           {failed_to_start_child,helper,^M
                            {{badmatch,{error,{not_active_local,emqx_routing_node}}},^M
                             [{emqx_router_helper,init,,^M
                               [{file,^M
                                 "/emqx_temp/emqx_rel/_checkouts/emqx/src/emqx_router_helper.erl"},^M
                                {line,}]},^M
                              {gen_server,init_it,,^M
                               [{file,"gen_server.erl"},{line,}]},^M
                              {gen_server,init_it,,^M
                               [{file,"gen_server.erl"},{line,}]},^M
                              {proc_lib,init_p_do_apply,,^M
                               [{file,"proc_lib.erl"},{line,}]}]}}}}}}},^M
                      [{emqx_app,start,,^M
                        [{file,^M
                          "/emqx_temp/emqx_rel/_checkouts/emqx/src/emqx_app.erl"},^M
                         {line,}]},^M
                       {application_master,start_it_old,,^M
                        [{file,"application_master.erl"},{line,}]}]}}}}^M
          type: permanent^M
      [os_mon] memory supervisor port (memsup): Erlang has closed^M
      [os_mon] cpu supervisor port (cpu_sup): Erlang has closed^M
      {"Kernel pid terminated",application_controller,"{application_start_failure,emqx,{bad_return,{{emqx_app,start,[normal,[]]},{'EXIT',{{badmatch,{error,{shutdown,{failed_to_start_child,emqx_router_sup,{shutdown,{failed_to_start_chi
        ld,helper,{{badmatch,{error,{not_active_local,emqx_routing_node}}},[{emqx_router_helper,init,,[{file,\"/emqx_temp/emqx_rel/_checkouts/emqx/src/emqx_router_helper.erl\"},{line,95}]},{gen_server,init_it,2,[{file,\"gen_server.erl\
        "},{line,374}]},{gen_server,init_it,6,[{file,\"gen_server.erl\"},{line,342}]},{proc_lib,init_p_do_apply,3,[{file,\"proc_lib.erl\"},{line,249}]}]}}}}}}},[{emqx_app,start,2,[{file,\"/emqx_temp/emqx_rel/_checkouts/emqx/src/emqx_app
        .erl\"},{line,32}]},{application_master,start_it_old,4,[{file,\"application_master.erl\"},{line,277}]}]}}}}}"}^M^M
      Kernel pid terminated (application_controller) ({application_start_failure,emqx,{bad_return,{{emqx_app,start,[normal,[]]},{'EXIT',{{badmatch,{error,{shutdown,{failed_to_start_child,emqx_router_sup,{sh^M^M
      ^M^M
      Crash dump is being written to: /var/log/emqx/crash.dump...done^M^M

什么意思呢？其实就是在安装路径的/var/lib/emqx下面有些异常数据，导致emqx启动时做数据同步时，出现错误，最后就宕机了。解决办法，就是将/var/lib/emqx下的数据清除掉，然后重新安装，当然，相关的配置，需要再次配置一下。

最后，再次将emqx安装一遍，就没有什么问题了。