Test Case

Various CPython test cases have started failing when moving from wasmtime 13 to 16 due to ESPIPE. Adding --wasi threads=y fixes the issue which seems unrelated to file seeking.

Example failure run can be seen at https://buildbot.python.org/all/#/builders/1124/builds/640/steps/11/logs/stdio right after I switched to wasmtime 16 from 13 (wasmtime 14.0.4 does not seem to have the issue).

Steps to Reproduce

• git clone https://github.com/python/cpython.git
• cd cpython
• python3 Tools/wasm/wasi.py build
• Edit cross-build/wasm32-wasi/python.sh and remove --wasi threads=y
• ./cross-build/wasm32-wasi/python.sh -m test test___all__

You can also try test___all__ test_bufio test_compileall test_dbm_dumb test_importlib test_io test_marshal test_pathlib test_posix test_runpy test_tarfile test_zipfile .

Expected Results

The test should pass w/o issue (it was working fine under wasmtime 13 w/ e.g. wasmtime run --env PYTHONPATH=/builddir/wasi/build/lib.wasi-wasm32-3.12:/Lib --mapdir /::/home/brettcannon/Repositories/python/cpython-3.12 -- python.wasm.

Actual Results

W/o --wasi threads=y, it causes a ESPIPE.

Versions and Environment

Wasmtime version or commit: 16.0.0 and 15.0.1

Operating system: Linux

Architecture: x64

Extra Info

WASI-SDK 20.