This is an old revision of the document!
"sendKillCmdToWatchdog" is normal
You may see the following from error_log:
2019-04-22 20:35:30.124450 NOTICE [2348767] Cmd from child: [extappkill:2348876:-3:0] 2019-04-22 20:35:36.113564 NOTICE [2348803] sendKillCmdToWatchdog: 'extappkill:2349000:-3:0'. 2019-04-22 20:35:36.113670 NOTICE [2348767] Cmd from child: [extappkill:2349000:-3:0] 2019-04-22 20:35:36.293086 NOTICE [2348803] sendKillCmdToWatchdog: 'extappkill:2349042:-3:0'.
That's normal messages and you can ignore those messages.
You can do not want to see those messages, just set log level to WARNING
.