CODEWITHSUNDEEP
multithreadinggdb
user4385532
user4385532

Reputation:

Can I debug in gdb multiple processes and/or threads simultaneously, that is, halting all of them once one hits a breakpoint?

As in the title.

Sometimes step-by-step debugging of a process or a thread becomes inconvenient if other threads/processes continue their execution at full speed.

Bonus if it was possible to debug this way two processes when they were both started independently from bash (and not one a child of the other).

Upvotes: 1

Views: 1226

Answers (1)

Employed Russian
Employed Russian

Reputation: 213879

For threads, this should already be happening.

GDB by default executes inferior in all-stop mode. In that mode, GDB will stop all threads as soon as one thread stops (either because it received a signal, or because it encountered a breakpoint). See also this answer.

While GDB also supports multiple inferiors, I don't believe there are any mechanisms to perform a "stop all inferiors" equivalent to "stop all threads" built in to GDB.

However, you can trivially achieve that with a command attached to your breakpoint:

(gdb) break foo.c:1234
(gdb) commands 1
  shell kill -STOP 4321   # stop the other inferior
end

Bonus if it was possible to debug this way two processes when they were both started independently from bash

Sure: you can attach both processes to the current GDB ((gdb) help attach) or to separate ones. It doesn't much matter where they were started from.

Upvotes: 1

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