ProxySQL: Watchdog: 1 threads missed a heartbeat

[Alex Porto dos Santos]

Hello,

I have a problem in ProxySQL and I'm not able to identify the cause.

In my scenario I have ProxySQL ahead of Galera Cluster.

I am using scheduler with check script.

I start receiving messages

```

2021-06-09 06:30:52 main.cpp:1885:main(): [ERROR] Watchdog: 1 threads missed a heartbeat

2021-06-09 06:30:55 main.cpp:1885:main(): [ERROR] Watchdog: 1 threads missed a heartbeat

2021-06-09 06:30:55 main.cpp:1889:main(): [ERROR] Watchdog: reached 10 missed heartbeats. Aborting!

2021-06-09 06:30:55 main.cpp:1890:main(): [ERROR] Watchdog: see details at https://github.com/sysown/proxysql/wiki/Watchdog

proxysql: main.cpp:1891: int main(int, const char**): Assertion `0' failed.

Error: signal 6:

/usr/bin/proxysql(_Z13crash_handleri+0x2a)[0x55ca956fdc8a]

/lib/x86_64-linux-gnu/libc.so.6(+0x37840)[0x7fe0795e5840]

/lib/x86_64-linux-gnu/libc.so.6(gsignal+0x10b)[0x7fe0795e57bb]

/lib/x86_64-linux-gnu/libc.so.6(abort+0x121)[0x7fe0795d0535]

/lib/x86_64-linux-gnu/libc.so.6(+0x2240f)[0x7fe0795d040f]

/lib/x86_64-linux-gnu/libc.so.6(+0x30102)[0x7fe0795de102]

/usr/bin/proxysql(main+0xed5)[0x55ca956e5075]

/lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xeb)[0x7fe0795d209b]

/usr/bin/proxysql(_start+0x2a)[0x55ca956f643a]

 ---- /usr/bin/proxysql(_Z13crash_handleri+0x2a) [0x55ca956fdc8a] : crash_handler(int)

Wed Jun  9 06:31:07 -03 2021 log file /var/lib/proxysql/proxysql.log

2021-06-09 06:33:52 main.cpp:1593:ProxySQL_daemonize_phase3(): [ERROR] ProxySQL crashed. Restarting!

``` 

After it restarts it gets this error, seeing this, I restart again and everything works again, for a while.
```

Wed Jun  9 06:34:59 -03 2021 ###### Another process is already running. Abort! ######

Wed Jun  9 06:35:09 -03 2021 ###### Another process is already running. Abort! ######

Wed Jun  9 06:35:19 -03 2021 ###### Another process is already running. Abort! ######

Wed Jun  9 06:35:29 -03 2021 ###### Another process is already running. Abort! ###
```

Has anyone ever seen something like this. or could you tell me some strategy to deal with it?

The complete log is attached.