breakpoint_test.py

"""
An updated version of https://gist.github.com/markshannon/da7588db3c883dc2006a727a10e00ca5.
"""
import timeit
import sys


def foo():
    for i in range(100_000):
        if i == 50_000:
            pass  # Put breakpoint here


print("No debug")

print(timeit.timeit(foo, number=100))

DEBUGGER_ID = 0

if sys.version_info.minor >= 12:
    print("PEP 669")

    break_count = 0


    def pep_669_breakpoint(code, line):
        global break_count
        if line == 11:
            break_count += 1
        else:
            return sys.monitoring.DISABLE

    sys.monitoring.use_tool_id(DEBUGGER_ID, "debugger")
    sys.monitoring.register_callback(DEBUGGER_ID, sys.monitoring.events.LINE, pep_669_breakpoint)
    sys.monitoring.set_local_events(DEBUGGER_ID, foo.__code__, sys.monitoring.events.LINE)

    print(timeit.timeit(foo, number=100))

    sys.monitoring.set_local_events(DEBUGGER_ID, foo.__code__, 0)

    print("Break point hit", break_count, "times")

break_count = 0
# Use sys.settrace, this is about as fast as a sys.settrace debugger can be if written in Python.

print("sys.settrace")

foo_code = foo.__code__


def sys_settrace_breakpoint(frame, event, arg):
    global break_count
    if frame.f_code is not foo_code:
        return None
    if event == "line" and frame.f_lineno == 11:
        break_count += 1
    return sys_settrace_breakpoint


sys.settrace(sys_settrace_breakpoint)

print(timeit.timeit(foo, number=100))

sys.settrace(None)

print("Break point hit", break_count, "times")

Test run output (Python 3.12.0rc1):

No debug
0.2007869999997638
PEP 669
0.2106258000003436
Break point hit 100 times
sys.settrace
3.493140599999606
Break point hit 100 times