how to find the reason when process exits abnormal?

how to find the position in programme when process exits abnormally after
several days?

if you have running “dumper” type “gdb your_file /var/dumps/your_file.core”.

the result of core file includes “???” and can’t give me any information,why?

It Becouse your application not have debug information. Rebuild project with debug information(debug, not release)