服务器程序处于无限循环中。 如何检查？

Question

A server program is on an infinite loop. How to check for it?

My solution:

use GDB to check the values of condition variables that control the loop.

It is ok for small program.

how to do that for large program ?

If the program is not running in GDB, how to detect the endless loop ?

thanks

Answer 1

You could use some form of a watchdog timer . Have the program output a character or touch a file periodically, so if it gets stuck in a loop, a separate process can detect that the watchdog has not been updated and kill/reset the process.

A lot of microcontrollers have this built into the hardware, and they will automatically reset if you don't reset the timer. It's very handy :)

Answer 2

If the program is running on the server you can attach a GDB process to it by giving its pid.

So for example look for the pid of the process using ps:

ps ax | grep server_process

3789   ??  S      0:00.58 /usr/bin/server_process
3790   ??  S      0:00.58 /usr/bin/server_process
18002  ??  S      0:00.58 grep server_process

You probably want the child:

so use gdb to attach to the running process

gdb /usr/bin/server_process 3790

.... loads symbols

gdb>

Happy tracing :)

Of course replace server_process with your program name and the path appropriately :P

Answer 3

Detecting an infinite loop is called the Halting problem which is undecidable.

So in principle there is no sure way to detect it.