sis for_all_nodes deadlock log

zeyer@indigo ~> py-spy dump --pid 17326
Process 17326: python3 ./python-tf.bin demo-import-tensorflow.py
Python v3.8.0 (/work/tools/asr/python/3.8.0/bin/python3.8)

Thread 17326 (idle): "MainThread"
    for_all_nodes (sisyphus/graph.py:569)
    set_job_targets (sisyphus/graph.py:686)
    __init__ (sisyphus/manager.py:218)
    manager (sisyphus/manager.py:98)
    main (sisyphus/__main__.py:220)
    <module> (sis:14)
    _run_code (runpy.py:85)
    _run_module_code (runpy.py:95)
    run_path (runpy.py:262)
    child_run (preloaded/utils.py:45)
    server_handle_child (preloaded/fork_server.py:138)
    server_main (preloaded/fork_server.py:99)
    startup_via_fork_server (preloaded/startup.py:68)
    <module> (python-tf.bin:11)
Thread 17351 (idle): "Thread-1"
    run (sisyphus/localengine.py:204)
    wrapped_func (sisyphus/tools.py:308)
    _bootstrap_inner (threading.py:932)
    _bootstrap (threading.py:890)
Thread 17352 (idle): "Thread-2"
    run (sisyphus/localengine.py:204)
    wrapped_func (sisyphus/tools.py:308)
    _bootstrap_inner (threading.py:932)
    _bootstrap (threading.py:890)
Thread 17353 (idle): "Thread-4"
    worker (multiprocessing/pool.py:114)
    run (threading.py:870)
    _bootstrap_inner (threading.py:932)
    _bootstrap (threading.py:890)
Thread 17354 (idle): "Thread-5"
    worker (multiprocessing/pool.py:114)
    run (threading.py:870)
    _bootstrap_inner (threading.py:932)
    _bootstrap (threading.py:890)
Thread 17356 (idle): "Thread-7"
    worker (multiprocessing/pool.py:114)
    run (threading.py:870)
    _bootstrap_inner (threading.py:932)
    _bootstrap (threading.py:890)
Thread 17357 (idle): "Thread-8"
    worker (multiprocessing/pool.py:114)
    run (threading.py:870)
    _bootstrap_inner (threading.py:932)
    _bootstrap (threading.py:890)
Thread 17358 (idle): "Thread-9"
    worker (multiprocessing/pool.py:114)
    run (threading.py:870)
    _bootstrap_inner (threading.py:932)
    _bootstrap (threading.py:890)
Thread 17359 (idle): "Thread-10"
    worker (multiprocessing/pool.py:114)
    run (threading.py:870)
    _bootstrap_inner (threading.py:932)
    _bootstrap (threading.py:890)
Thread 17360 (idle): "Thread-11"
    worker (multiprocessing/pool.py:114)
    run (threading.py:870)
    _bootstrap_inner (threading.py:932)
    _bootstrap (threading.py:890)
Thread 17361 (idle): "Thread-12"
    worker (multiprocessing/pool.py:114)
    run (threading.py:870)
    _bootstrap_inner (threading.py:932)
    _bootstrap (threading.py:890)
Thread 17362 (idle): "Thread-13"
    worker (multiprocessing/pool.py:114)
    run (threading.py:870)
    _bootstrap_inner (threading.py:932)
    _bootstrap (threading.py:890)
Thread 17363 (idle): "Thread-14"
    worker (multiprocessing/pool.py:114)
    run (threading.py:870)
    _bootstrap_inner (threading.py:932)
    _bootstrap (threading.py:890)
Thread 17364 (idle): "Thread-15"
    worker (multiprocessing/pool.py:114)
    run (threading.py:870)
    _bootstrap_inner (threading.py:932)
    _bootstrap (threading.py:890)
Thread 17365 (idle): "Thread-16"
    worker (multiprocessing/pool.py:114)
    run (threading.py:870)
    _bootstrap_inner (threading.py:932)
    _bootstrap (threading.py:890)
Thread 17366 (idle): "Thread-17"
    worker (multiprocessing/pool.py:114)
    run (threading.py:870)
    _bootstrap_inner (threading.py:932)
    _bootstrap (threading.py:890)
Thread 17367 (idle): "Thread-18"
    worker (multiprocessing/pool.py:114)
    run (threading.py:870)
    _bootstrap_inner (threading.py:932)
    _bootstrap (threading.py:890)
Thread 17368 (idle): "Thread-19"
    worker (multiprocessing/pool.py:114)
    run (threading.py:870)
    _bootstrap_inner (threading.py:932)
    _bootstrap (threading.py:890)
Thread 17369 (idle): "Thread-20"
    select (selectors.py:415)
    wait (multiprocessing/connection.py:930)
    _wait_for_updates (multiprocessing/pool.py:499)
    _handle_workers (multiprocessing/pool.py:519)
    run (threading.py:870)
    _bootstrap_inner (threading.py:932)
    _bootstrap (threading.py:890)
Thread 17370 (idle): "Thread-21"
    _handle_tasks (multiprocessing/pool.py:528)
    run (threading.py:870)
    _bootstrap_inner (threading.py:932)
    _bootstrap (threading.py:890)
Thread 17371 (idle): "Thread-22"
    _handle_results (multiprocessing/pool.py:576)
    run (threading.py:870)
    _bootstrap_inner (threading.py:932)
    _bootstrap (threading.py:890)