I have a program which uses two threads. I have put the break point in both the threads. While running the program under gdb I want to switch between the threads and make them run. (thread t1 is active and running and thread t2; when paused on the breakpoint. I want to stop T1 running and run the T2).
Is there any 开发者_C百科way that I can schedule the threads in gdb?
By default, GDB stops all threads when any breakpoint is hit, and resumes all threads when you issue any command (such as continue
, next
, step
, finish
, etc.) which requires that the inferior process (the one you are debugging) start to execute.
However, you can tell GDB not to do that:
(gdb) help set scheduler-locking
Set mode for locking scheduler during execution.
off == no locking (threads may preempt at any time)
on == full locking (no thread except the current thread may run)
step == scheduler locked during every single-step operation.
In this mode, no other thread may run during a step command.
Other threads may run while stepping over a function call ('next').
So you'll want to set breakpoints, then set scheduler-locking on
, then continue
or finish
in thread 1 (thread 2 is still stopped), then Ctrl-C to regain control of GDB, switch to thread 2, continue
(thread 1 is still stopped), etc.
Beware: by setting scheduler-locking on
it is very easy to cause the inferior process to self-deadlock.
If you're using GDB 7 or later, try "non-stop mode".
http://sourceware.org/gdb/current/onlinedocs/gdb/Non_002dStop-Mode.html
The "scheduler-locking on" command previously mentioned allows you step one thread with the others stopped. Non-stop mode allows you to step one thread with the others active.
use break conditions
(gdb) break frik.c:13 thread 28 if bartab > lim
see Debugging with GDB
Edit:
(gdb) break <thread_function_entry_point> thread 2
(gdb) break <thread_function_entry_point> thread 1
(gdb) thread 1
(gdb) continue
(gdb) ... thread 1 finishes
(gdb) thread 2
(gdb) continue
You can put these commands inside a .gdbrc file.
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