import sys
import concurrent.futures
import threading
if __name__ == "__main__":
    num_workers = 20
    num_runs = 100
    barrier = threading.Barrier(num_workers)
    tool_id = 3
    event_id = sys.monitoring.events.CALL
    sys.monitoring.use_tool_id(tool_id, "test_tool_1")
    sys.monitoring.set_events(tool_id, event_id)
    def closure():
        barrier.wait()
        def my_callback(code, instruction_offset, callable, arg0):
            pass
        sys.monitoring.register_callback(tool_id, event_id, my_callback)
        def example_function():
            a = 1
            b = 2
            c = a + b
        for _ in range(num_runs):
            example_function()
    with concurrent.futures.ThreadPoolExecutor(max_workers=num_workers) as executor:
        futures = []
        for i in range(num_workers):
            futures.append(executor.submit(closure))
        assert len(list(f.result() for f in futures)) == num_workers

Python 3.13.2+ experimental free-threading build (heads/3.13:9e0fce413a9, Mar 12 2025, 00:48:15) [Clang 18.1.3 (1ubuntu1)]