threadutil.pl -- Interactive thread utilities

This library provides utilities that are primarily intended for interactive usage in a threaded Prolog environment. It allows for inspecting threads, manage I/O of background threads (depending on the environment) and manipulating the debug status of threads.

threads

List currently known threads with their status.

join_threads

Join all terminated threads.

with_stopped_threads(:Goal, Options) is det

Stop all threads except the caller while running once(Goal). Note that this is in the thread user utilities as this is not something that should be used by normal applications. Notably, this may deadlock if the current thread requires input from some other thread to complete Goal or one of the stopped threads has a lock. Options:

stop_nodebug_threads(+Boolean): If true (default false), also stop threads created with the debug(false) option.
except(+List): Do not stop threads from this list.

bug: - Note that the threads are stopped when they process signals. As signal handling may be delayed, this implies they need not be stopped before Goal starts.

thread_has_console is semidet

True when the calling thread has an attached console.

See also: - attach_console/0

xterm_args(-List) is nondet[multifile]

Multifile and dynamic hook that provides (additional) arguments for the xterm(1) process opened for additional thread consoles. Each solution must bind List to a list of atomic values. All solutions are concatenated using append/2 to form the final argument list.

The defaults set the colors to black-on-light-yellow, enable a scrollbar, set the font using Xft font pattern and prepares the back-arrow key.

attach_console is det

attach_console(?Title) is det

Create a new console and make the standard Prolog streams point to it. If not provided, the title is built using the thread id. Does nothing if the current thread already has a console attached.

interactor is det

interactor(?Title) is det

Run a Prolog toplevel in another thread with a new console window. If Title is given, this will be used as the window title.

thread_run_interactor

Attach a console and run a Prolog toplevel in the current thread.

tspy(:Spec) is det

tspy(:Spec, +ThreadId) is det

Trap the graphical debugger on reaching Spec in the specified or any thread.

tdebug is det

tdebug(+Thread) is det

Enable debug-mode, trapping the graphical debugger on reaching spy-points or errors.

tnodebug is det

tnodebug(+Thread) is det

Disable debug-mode in all threads or the specified Thread.

tbacktrace(+Thread) is det

tbacktrace(+Thread, +Options) is det

Print a backtrace for Thread to the stream user_error of the calling thread. This is achieved by inserting an interrupt into Thread using call_in_thread/2. Options:

depth(+MaxFrames): Number of stack frames to show. Default is the current Prolog flag backtrace_depth or 20.

Other options are passed to get_prolog_backtrace/3.

bug: - call_in_thread/2 may not process the event.

tprofile(+Thread) is det

Profile the operation of Thread until the user hits a key.

Re-exported predicates

The following predicates are exported from this file while their implementation is defined in imported modules or non-module files loaded by this module.