Debugging with GDB: Threads In Python

Debugging with GDB: Threads In Python

23.2.2.18 Threads In Python

Python scripts can access information about, and manipulate inferior threads controlled by GDB, via objects of the gdb.InferiorThread class.

The following thread-related functions are available in the gdb module:

Function: gdb.selected_thread (): This function returns the thread object for the selected thread. If there is no selected thread, this will return None.

A gdb.InferiorThread object has the following attributes:

Variable: InferiorThread.name

The name of the thread. If the user specified a name using thread name, then this returns that name. Otherwise, if an OS-supplied name is available, then it is returned. Otherwise, this returns None.

This attribute can be assigned to. The new value must be a string object, which sets the new name, or None, which removes any user-specified thread name.

Variable: InferiorThread.num: The per-inferior number of the thread, as assigned by GDB.

Variable: InferiorThread.global_num: The global ID of the thread, as assigned by GDB. You can use this to make Python breakpoints thread-specific, for example (see The Breakpoint.thread attribute).

Variable: InferiorThread.ptid: ID of the thread, as assigned by the operating system. This attribute is a tuple containing three integers. The first is the Process ID (PID); the second is the Lightweight Process ID (LWPID), and the third is the Thread ID (TID). Either the LWPID or TID may be 0, which indicates that the operating system does not use that identifier.

Variable: InferiorThread.inferior: The inferior this thread belongs to. This attribute is represented as a gdb.Inferior object. This attribute is not writable.

A gdb.InferiorThread object has the following methods:

Function: InferiorThread.is_valid (): Returns True if the gdb.InferiorThread object is valid, False if not. A gdb.InferiorThread object will become invalid if the thread exits, or the inferior that the thread belongs is deleted. All other gdb.InferiorThread methods will throw an exception if it is invalid at the time the method is called.

Function: InferiorThread.switch (): This changes GDB’s currently selected thread to the one represented by this object.

Function: InferiorThread.is_stopped (): Return a Boolean indicating whether the thread is stopped.

Function: InferiorThread.is_running (): Return a Boolean indicating whether the thread is running.

Function: InferiorThread.is_exited (): Return a Boolean indicating whether the thread is exited.