Function dispatch

mypy/build.py:4057–4172

(
    sources: list[BuildSource],
    manager: BuildManager,
    stdout: TextIO,
    connect_threads: list[Thread],
)

def dispatch(
    sources: list[BuildSource],
    manager: BuildManager,
    stdout: TextIO,
    connect_threads: list[Thread],
) -> Graph:
    log_configuration(manager, sources)

    t0 = time.time()

    # We disable GC while loading the graph as a performance optimization for
    # cold-cache runs. The parsed ASTs are trees, and therefore should not have any
    # reference cycles. This is an important optimization, since we create a lot of
    # new objects while parsing files.
    global initial_gc_freeze_done
    if (
        not manager.options.test_env
        and platform.python_implementation() == "CPython"
        and not initial_gc_freeze_done
    ):
        gc.disable()
    graph = load_graph(sources, manager)

    # This is a kind of unfortunate hack to work around some of fine-grained's
    # fragility: if we have loaded less than 50% of the specified files from
    # cache in fine-grained cache mode, load the graph again honestly.
    # In this case, we just turn the cache off entirely, so we don't need
    # to worry about some files being loaded and some from cache and so
    # that fine-grained mode never *writes* to the cache.
    if manager.use_fine_grained_cache() and len(graph) < 0.50 * len(sources):
        manager.log("Redoing load_graph without cache because too much was missing")
        manager.cache_enabled = False
        graph = load_graph(sources, manager)

    if (
        not manager.options.test_env
        and platform.python_implementation() == "CPython"
        and not initial_gc_freeze_done
    ):
        gc.freeze()
        gc.unfreeze()
        gc.enable()
        initial_gc_freeze_done = True

    for id in graph:
        manager.import_map[id] = graph[id].dependencies_set

    t1 = time.time()
    manager.add_stats(
        graph_size=len(graph),
        stubs_found=sum(g.path is not None and g.path.endswith(".pyi") for g in graph.values()),
        graph_load_time=(t1 - t0),
        fm_cache_size=len(manager.find_module_cache.results),
    )
    if not graph:
        print("Nothing to do?!", file=stdout)
        return graph
    manager.log(f"Loaded graph with {len(graph)} nodes ({t1 - t0:.3f} sec)")