[Bug] Tune fails on macOS

[gmeeker]

tvmc tune appears to have broken between 0.12.0 and 0.13.0.

Expected behavior

Produce an autotuner json file (which worked in 0.12.0).

Actual behavior

[Task  1/25]  Current/Best:    0.00/   0.00 GFLOPS | Progress: (0/40) | 0.00 sException in thread Thread-1:
Traceback (most recent call last):
  File "/usr/local/Cellar/python@3.8/3.8.18/Frameworks/Python.framework/Versions/3.8/lib/python3.8/threading.py", line 932, in _bootstrap_inner
    self.run()
  File "/usr/local/Cellar/python@3.8/3.8.18/Frameworks/Python.framework/Versions/3.8/lib/python3.8/threading.py", line 870, in run
    self._target(*self._args, **self._kwargs)
  File "/Users/gmeeker/src/tvm_0.13.0/python/tvm/rpc/server.py", line 272, in _listen_loop
    _serving(conn, addr, opts, load_library)
  File "/Users/gmeeker/src/tvm_0.13.0/python/tvm/rpc/server.py", line 143, in _serving
    server_proc.start()
  File "/usr/local/Cellar/python@3.8/3.8.18/Frameworks/Python.framework/Versions/3.8/lib/python3.8/multiprocessing/process.py", line 121, in start
    self._popen = self._Popen(self)
  File "/usr/local/Cellar/python@3.8/3.8.18/Frameworks/Python.framework/Versions/3.8/lib/python3.8/multiprocessing/context.py", line 224, in _Popen
    return _default_context.get_context().Process._Popen(process_obj)
  File "/usr/local/Cellar/python@3.8/3.8.18/Frameworks/Python.framework/Versions/3.8/lib/python3.8/multiprocessing/context.py", line 284, in _Popen
    return Popen(process_obj)
  File "/usr/local/Cellar/python@3.8/3.8.18/Frameworks/Python.framework/Versions/3.8/lib/python3.8/multiprocessing/popen_spawn_posix.py", line 32, in __init__
    super().__init__(process_obj)
  File "/usr/local/Cellar/python@3.8/3.8.18/Frameworks/Python.framework/Versions/3.8/lib/python3.8/multiprocessing/popen_fork.py", line 19, in __init__
    self._launch(process_obj)
  File "/usr/local/Cellar/python@3.8/3.8.18/Frameworks/Python.framework/Versions/3.8/lib/python3.8/multiprocessing/popen_spawn_posix.py", line 47, in _launch
    reduction.dump(process_obj, fp)
  File "/usr/local/Cellar/python@3.8/3.8.18/Frameworks/Python.framework/Versions/3.8/lib/python3.8/multiprocessing/reduction.py", line 60, in dump
    ForkingPickler(file, protocol).dump(obj)
AttributeError: Can't pickle local object '_serving.<locals>._serve_loop'

This looks similar to #8363 and #8347 although those are older than 0.12.0 which is working on macOS.

Environment

macOS 13.5.2
Python 3.8.18
TVM 0.13.0 or current head of main branch

Steps to reproduce

Compiled using brew per install from source instructions:
https://tvm.apache.org/docs/install/from_source.html

Run tvmc tune --target "llvm" --output resnet50-v2-7-autotuner_records.json resnet50-v2-7.onnx as described here:
https://tvm.apache.org/docs/tutorial/tvmc_command_line_driver.html

Triage

• needs-triage
• tune:autotvm

[Johnson9009]

Thanks @gmeeker for the fix, because the PR #16357 is merged, so this bug will be closed.