When your program has multiple threads (see Debugging Programs with Multiple Threads), you can choose whether to set breakpoints on all threads, or on a particular thread.
Use the qualifier `thread threadno' with a breakpoint command to specify that you only want gdb to stop the program when a particular thread reaches this breakpoint. threadno is one of the numeric thread identifiers assigned by gdb, shown in the first column of the `info threads' display.
If you do not specify `thread threadno' when you set a breakpoint, the breakpoint applies to all threads of your program.
You can use the
thread qualifier on conditional breakpoints as
well; in this case, place `thread threadno' before or
after the breakpoint condition, like this:
(gdb) break frik.c:13 thread 28 if bartab > lim