threadpoolctl/tests/test_threadpoolctl.py at master · joblib/threadpoolctl

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from __future__ import annotations

import ctypes

import json

import os

import re

import shutil

import subprocess

import sys

import time

from threading import Lock, Thread, current_thread

import pytest

import threadpoolctl

from threadpoolctl import (

_ALL_PREFIXES,

_ALL_USER_APIS,

CONTROLLING_THREAD_OWNERSHIP,

LibController,

OpenBLASController,

ThreadpoolController,

_determine_thread_limit_scope,

get_cached_controller,

reset_cached_controller,

threadpool_info,

threadpool_limits,

)

from .utils import (

check_nested_prange_blas,

cython_extensions_compiled,

get_openblas_dll_path,

libopenblas_paths,

make_long_windows_path,

scipy,

select,

threadpool_info_from_subprocess,

)

def is_old_openblas(lib_controller):

# Possible bug in getting maximum number of threads with OpenBLAS < 0.2.16

# and OpenBLAS does not expose its version before 0.3.4.

return lib_controller.internal_api == "openblas" and lib_controller.version is None

def skip_if_openblas_openmp():

"""Helper to skip tests with side effects when OpenBLAS has the OpenMP

threading layer.

"""

if any(

lib_controller.internal_api == "openblas"

and lib_controller.threading_layer == "openmp"

for lib_controller in ThreadpoolController().lib_controllers

pytest.skip(

"Setting a limit on OpenBLAS when using the OpenMP threading layer also "

"impact the OpenMP library. They can't be controlled independently."

)

def effective_num_threads(nthreads, max_threads):

if nthreads is None or nthreads > max_threads:

return max_threads

return nthreads

def test_threadpool_info():

# Check consistency between threadpool_info and ThreadpoolController

function_info = threadpool_info()

object_info = ThreadpoolController().lib_controllers

for lib_info, lib_controller in zip(function_info, object_info):

assert lib_info == lib_controller.info()

def test_threadpool_controller_info():

# Check that all keys expected for the private api are in the dicts

# returned by the `info` methods

controller = ThreadpoolController()

assert threadpool_info() == [

lib_controller.info() for lib_controller in controller.lib_controllers

]

assert controller.info() == [

lib_controller.info() for lib_controller in controller.lib_controllers

]

for lib_controller_dict in controller.info():

assert "user_api" in lib_controller_dict

assert "internal_api" in lib_controller_dict

assert "prefix" in lib_controller_dict

assert "filepath" in lib_controller_dict

assert "version" in lib_controller_dict

assert "num_threads" in lib_controller_dict

if lib_controller_dict["internal_api"] in ("mkl", "blis", "openblas"):

assert "threading_layer" in lib_controller_dict

def test_controller_info_actualized():

# Check that the num_threads attribute reflects the actual state of the threadpools

controller = ThreadpoolController()

original_info = controller.info()

with threadpool_limits(limits=1):

assert all(

lib_controller.num_threads == 1

for lib_controller in controller.lib_controllers

)

assert controller.info() == original_info

@pytest.mark.parametrize(

"kwargs",

[

{"user_api": "blas"},

{"prefix": "libgomp"},

{"internal_api": "openblas", "prefix": "libomp"},

{"prefix": ["libgomp", "libomp", "libiomp"]},

)

def test_threadpool_controller_select(kwargs):

# Check the behior of the select method of ThreadpoolController

controller = ThreadpoolController().select(**kwargs)

if not controller:

pytest.skip(f"Requires at least one of {list(kwargs.values())}.")

for lib_controller in controller.lib_controllers:

assert any(

getattr(lib_controller, key) in (val if isinstance(val, list) else [val])

for key, val in kwargs.items()

)

@pytest.mark.parametrize(

"to_structure",

[

lambda filepath, limit: [{"filepath": filepath, "num_threads": limit}],

lambda filepath, limit: {filepath: limit},

)

@pytest.mark.parametrize("limit", [1, 3])

def test_threadpool_limits_by_filepath(to_structure, limit):

controller = ThreadpoolController()

original_info = controller.info()

for lib_controller in controller.lib_controllers:

with threadpool_limits(limits=to_structure(lib_controller.filepath, limit)):

# threadpool_limits only sets an upper bound on the number of

# threads.

assert 0 < lib_controller.num_threads <= limit

assert ThreadpoolController().info() == original_info

@pytest.mark.skipif(scipy is None, reason="need numpy and scipy")

def test_threadpool_limits_prioritizes_filepath_over_prefix():

controller = ThreadpoolController()

openblases = controller.select(internal_api="openblas").lib_controllers

if len(openblases) < 2 or len({ob.prefix for ob in openblases}) == len(openblases):

pytest.skip("Need two OpenBLASes with same prefix")

with controller.limit(limits={openblases[0].filepath: 1, openblases[1].prefix: 3}):

assert 0 <= openblases[0].get_num_threads() <= 1

assert 0 <= openblases[1].get_num_threads() <= 3

@pytest.mark.parametrize("prefix", _ALL_PREFIXES)

@pytest.mark.parametrize("limit", [1, 3])

def test_threadpool_limits_by_prefix(prefix, limit):

# Check that the maximum number of threads can be set by prefix

controller = ThreadpoolController()

original_info = controller.info()

controller_matching_prefix = controller.select(prefix=prefix)

if not controller_matching_prefix:

pytest.skip(f"Requires {prefix} runtime")

with threadpool_limits(limits={prefix: limit}):

for lib_controller in controller_matching_prefix.lib_controllers:

if is_old_openblas(lib_controller):

continue

# threadpool_limits only sets an upper bound on the number of

# threads.

assert 0 < lib_controller.num_threads <= limit

assert ThreadpoolController().info() == original_info

@pytest.mark.parametrize("user_api", (None, "blas", "openmp"))

@pytest.mark.parametrize("limit", [1, 3])

def test_set_threadpool_limits_by_api(user_api, limit):

# Check that the maximum number of threads can be set by user_api

controller = ThreadpoolController()

original_info = controller.info()

if user_api is None:

controller_matching_api = controller

else:

controller_matching_api = controller.select(user_api=user_api)

if not controller_matching_api:

user_apis = _ALL_USER_APIS if user_api is None else [user_api]

pytest.skip(f"Requires a library which api is in {user_apis}")

with threadpool_limits(limits=limit, user_api=user_api):

for lib_controller in controller_matching_api.lib_controllers:

if is_old_openblas(lib_controller):

continue

# threadpool_limits only sets an upper bound on the number of

# threads.

assert 0 < lib_controller.num_threads <= limit

assert ThreadpoolController().info() == original_info

def test_threadpool_limits_function_with_side_effect():

# Check that threadpool_limits can be used as a function with

# side effects instead of a context manager.

original_info = ThreadpoolController().info()

threadpool_limits(limits=1)

try:

for lib_controller in ThreadpoolController().lib_controllers:

if is_old_openblas(lib_controller):

continue

assert lib_controller.num_threads == 1

finally:

# Restore the original limits so that this test does not have any

# side-effect.

threadpool_limits(limits=original_info)

assert ThreadpoolController().info() == original_info

def test_set_threadpool_limits_no_limit():

# Check that limits=None does nothing.

original_info = ThreadpoolController().info()

with threadpool_limits(limits=None):

assert ThreadpoolController().info() == original_info

def test_threadpool_limits_manual_restore():

# Check that threadpool_limits can be used as an object which holds the

# original state of the threadpools and that can be restored thanks to the

# dedicated restore_original_limits method

original_info = ThreadpoolController().info()

limits = threadpool_limits(limits=1)

try:

for lib_controller in ThreadpoolController().lib_controllers:

if is_old_openblas(lib_controller):

continue

assert lib_controller.num_threads == 1

finally:

# Restore the original limits so that this test does not have any

# side-effect.

limits.restore_original_limits()

assert ThreadpoolController().info() == original_info

def test_threadpool_controller_limit():

# Check that using the limit method of ThreadpoolController only impact its

# library controllers.

# This is not True for OpenBLAS with the OpenMP threading layer.

skip_if_openblas_openmp()

blas_controller = ThreadpoolController().select(user_api="blas")

original_openmp_info = ThreadpoolController().select(user_api="openmp").info()

with blas_controller.limit(limits=1):

blas_controller = ThreadpoolController().select(user_api="blas")

openmp_info = ThreadpoolController().select(user_api="openmp").info()

assert all(

lib_controller.num_threads == 1

for lib_controller in blas_controller.lib_controllers

)

# original_blas_controller contains only blas libraries so no opemp library

# should be impacted.

assert openmp_info == original_openmp_info

def test_get_params_for_sequential_blas_under_openmp():

# Test for the behavior of get_params_for_sequential_blas_under_openmp.

controller = ThreadpoolController()

original_info = controller.info()

params = controller._get_params_for_sequential_blas_under_openmp()

if any(

lib_info["internal_api"] == "openblas"

and lib_info.get("threading_layer") == "openmp"

for lib_info in original_info

assert params["limits"] is None

assert params["user_api"] is None

with controller.limit(limits="sequential_blas_under_openmp"):

assert controller.info() == original_info

else:

assert params["limits"] == 1

assert params["user_api"] == "blas"

with controller.limit(limits="sequential_blas_under_openmp"):

assert all(

lib_info["num_threads"] == 1

for lib_info in controller.info()

if lib_info["user_api"] == "blas"

)

def test_nested_limits():

# Check that exiting the context manager properly restores the original limits even

# when nested.

controller = ThreadpoolController()

original_info = controller.info()

if any(info["num_threads"] < 2 for info in original_info):

pytest.skip("Test requires at least 2 CPUs on host machine")

def check_num_threads(expected_num_threads):

assert all(

lib_controller.num_threads == expected_num_threads

for lib_controller in ThreadpoolController().lib_controllers

)

with controller.limit(limits=1):

check_num_threads(expected_num_threads=1)

with controller.limit(limits=2):

check_num_threads(expected_num_threads=2)

check_num_threads(expected_num_threads=1)

assert ThreadpoolController().info() == original_info

def test_threadpool_limits_bad_input():

# Check that appropriate errors are raised for invalid arguments

match = re.escape(f"user_api must be either in {_ALL_USER_APIS} or None.")

with pytest.raises(ValueError, match=match):

threadpool_limits(limits=1, user_api="wrong")

with pytest.raises(

TypeError, match="limits must either be an int, a list, a dict, or"

threadpool_limits(limits=(1, 2, 3))

@pytest.mark.skipif(

not cython_extensions_compiled, reason="Requires cython extensions to be compiled"

)

@pytest.mark.parametrize("num_threads", [1, 2, 4])

def test_openmp_limit_num_threads(num_threads):

# checks that OpenMP effectively uses the number of threads requested by

# the context manager

import tests._openmp_test_helper.openmp_helpers_inner as omp_inner

check_openmp_num_threads = omp_inner.check_openmp_num_threads

old_num_threads = check_openmp_num_threads(100)

with threadpool_limits(limits=num_threads):

assert check_openmp_num_threads(100) in (num_threads, old_num_threads)

assert check_openmp_num_threads(100) == old_num_threads

@pytest.mark.skipif(

not cython_extensions_compiled, reason="Requires cython extensions to be compiled"

)

@pytest.mark.parametrize("nthreads_outer", [None, 1, 2, 4])

def test_openmp_nesting(nthreads_outer):

# checks that OpenMP effectively uses the number of threads requested by

# the context manager when nested in an outer OpenMP loop.

import tests._openmp_test_helper.openmp_helpers_outer as omp_outer

check_nested_openmp_loops = omp_outer.check_nested_openmp_loops

# Find which OpenMP lib is used at runtime for inner loop

inner_info = threadpool_info_from_subprocess(

"tests._openmp_test_helper.openmp_helpers_inner"

)

assert len(inner_info) == 1

inner_omp = inner_info[0]["prefix"]

# Find which OpenMP lib is used at runtime for outer loop

outer_info = threadpool_info_from_subprocess(

"tests._openmp_test_helper.openmp_helpers_outer"

)

if len(outer_info) == 1:

# Only 1 openmp loaded. It has to be this one.

outer_omp = outer_info[0]["prefix"]

else:

# There are 2 openmp, the one from inner and the one from outer.

assert len(outer_info) == 2

# We already know the one from inner. It has to be the other one.

prefixes = {lib_info["prefix"] for lib_info in outer_info}

outer_omp = prefixes - {inner_omp}

outer_num_threads, inner_num_threads = check_nested_openmp_loops(10)

original_info = ThreadpoolController().info()

if inner_omp == outer_omp:

# The OpenMP runtime should be shared by default, meaning that the

# inner loop should automatically be run serially by the OpenMP runtime

assert inner_num_threads == 1

with threadpool_limits(limits=1) as threadpoolctx:

max_threads = threadpoolctx.get_original_num_threads()["openmp"]

nthreads = effective_num_threads(nthreads_outer, max_threads)

# Ask outer loop to run on nthreads threads and inner loop run on 1

# thread

outer_num_threads, inner_num_threads = check_nested_openmp_loops(10, nthreads)

# The state of the original state of all threadpools should have been

# restored.

assert ThreadpoolController().info() == original_info

# The number of threads available in the outer loop should not have been

# decreased:

assert outer_num_threads == nthreads

# The number of threads available in the inner loop should have been

# set to 1 to avoid oversubscription and preserve performance:

if inner_omp != outer_omp: # noqa: SIM102

if inner_num_threads != 1:

# XXX: this does not always work when nesting independent openmp

# implementations. See: https://github.com/jeremiedbb/Nested_OpenMP

pytest.xfail(

f"Inner OpenMP num threads was {inner_num_threads} instead of 1"

)

assert inner_num_threads == 1

def test_shipped_openblas():

# checks that OpenBLAS effectively uses the number of threads requested by

# the context manager

original_info = ThreadpoolController().info()

openblas_controller = ThreadpoolController().select(internal_api="openblas")

with threadpool_limits(1):

for lib_controller in openblas_controller.lib_controllers:

assert lib_controller.num_threads == 1

assert ThreadpoolController().info() == original_info

@pytest.mark.skipif(

len(libopenblas_paths) < 2, reason="need at least 2 shipped openblas library"

)

def test_multiple_shipped_openblas():

# This redundant test is meant to make it easier to see if the system

# has 2 or more active openblas runtimes available just by reading the

# pytest report (whether or not this test has been skipped).

test_shipped_openblas()

@pytest.mark.skipif(

not cython_extensions_compiled, reason="Requires cython extensions to be compiled"

)

@pytest.mark.skipif(

check_nested_prange_blas is None,

reason="Requires nested_prange_blas to be compiled",

)

@pytest.mark.parametrize("nthreads_outer", [None, 1, 2, 4])

def test_nested_prange_blas(nthreads_outer):

# Check that the BLAS uses the number of threads requested by the context manager

# when nested in an outer OpenMP loop.

# Remark: this test also works with sequential BLAS only because we limit the

# number of threads for the BLAS to 1.

import numpy as np

skip_if_openblas_openmp()

original_info = ThreadpoolController().info()

blas_controller = ThreadpoolController().select(user_api="blas")

blis_controller = ThreadpoolController().select(internal_api="blis")

# skip if the BLAS used by numpy is an old openblas. OpenBLAS 0.3.3 and

# older are known to cause an unrecoverable deadlock at process shutdown

# time (after pytest has exited).

# numpy can be linked to BLIS for CBLAS and OpenBLAS for LAPACK. In that

# case this test will run BLIS gemm so no need to skip.

if not blis_controller and any(

is_old_openblas(lib_controller)

for lib_controller in blas_controller.lib_controllers

pytest.skip("Old OpenBLAS: skipping test to avoid deadlock")

A = np.ones((1000, 10))

B = np.ones((100, 10))

with threadpool_limits(limits=1) as threadpoolctx:

max_threads = threadpoolctx.get_original_num_threads()["openmp"]

nthreads = effective_num_threads(nthreads_outer, max_threads)

result = check_nested_prange_blas(A, B, nthreads)

C, prange_num_threads, inner_info = result

assert np.allclose(C, np.dot(A, B.T))

assert prange_num_threads == nthreads

nested_blas_info = select(inner_info, user_api="blas")

assert len(nested_blas_info) == len(blas_controller.lib_controllers)

assert all(lib_info["num_threads"] == 1 for lib_info in nested_blas_info)

assert ThreadpoolController().info() == original_info

# the method `get_original_num_threads` raises a UserWarning due to different

# num_threads from libraries with the same `user_api`. It will be raised only

# in the CI job with 2 openblas (py38_pip_openblas_gcc_clang). It is expected

# so we can safely filter it.

@pytest.mark.filterwarnings("ignore::UserWarning")

@pytest.mark.parametrize("limit", [1, None])

def test_get_original_num_threads(limit):

# Tests the method get_original_num_threads of the context manager

with threadpool_limits(limits=2, user_api="blas") as ctx:

# set different blas num threads to start with (when multiple openblas)

if len(ctx._controller.select(user_api="blas")) > 1:

ctx._controller.lib_controllers[0].set_num_threads(1)

original_info = ThreadpoolController().info()

with threadpool_limits(limits=limit, user_api="blas") as threadpoolctx:

original_num_threads = threadpoolctx.get_original_num_threads()

assert "openmp" not in original_num_threads

blas_info = select(original_info, user_api="blas")

if blas_info:

expected = min(lib_info["num_threads"] for lib_info in blas_info)

assert original_num_threads["blas"] == expected

else:

assert original_num_threads["blas"] is None

if len(libopenblas_paths) >= 2:

with pytest.warns(UserWarning, match="Multiple values possible"):

threadpoolctx.get_original_num_threads()

def test_mkl_threading_layer():

# Check that threadpool_info correctly recovers the threading layer used

# by mkl

mkl_controller = ThreadpoolController().select(internal_api="mkl")

expected_layer = os.getenv("MKL_THREADING_LAYER")

if not (mkl_controller and expected_layer):

pytest.skip("requires MKL and the environment variable MKL_THREADING_LAYER set")

actual_layer = mkl_controller.lib_controllers[0].threading_layer

assert actual_layer == expected_layer.lower()

def test_blis_threading_layer():

# Check that threadpool_info correctly recovers the threading layer used

# by blis

blis_controller = ThreadpoolController().select(internal_api="blis")

expected_layer = os.getenv("BLIS_ENABLE_THREADING")

if expected_layer == "no":

expected_layer = "disabled"

if not (blis_controller and expected_layer):

pytest.skip(

"requires BLIS and the environment variable BLIS_ENABLE_THREADING set"

)

actual_layer = blis_controller.lib_controllers[0].threading_layer

assert actual_layer == expected_layer

@pytest.mark.skipif(

not cython_extensions_compiled, reason="Requires cython extensions to be compiled"

)

def test_libomp_libiomp_warning(recwarn):

# Trigger the import of a potentially clang-compiled extension:

import tests._openmp_test_helper.openmp_helpers_outer # noqa

# Trigger the import of numpy to potentially import Intel OpenMP via MKL

pytest.importorskip("numpy.linalg")

# Check that a warning is raised when both libomp and libiomp are loaded

# It should happen in one CI job (pylatest_conda_mkl_clang_gcc).

controller = ThreadpoolController()

prefixes = [lib_controller.prefix for lib_controller in controller.lib_controllers]

if not ("libomp" in prefixes and "libiomp" in prefixes and sys.platform == "linux"):

pytest.skip("Requires both libomp and libiomp loaded, on Linux")

assert len(recwarn) == 1

wm = recwarn[0]

assert wm.category == RuntimeWarning

assert "Found Intel" in str(wm.message)

assert "LLVM" in str(wm.message)

assert "multiple_openmp.md" in str(wm.message)

def test_command_line_empty_or_system_openmp():

# When the command line is called without arguments, no library should be

# detected. The only exception is a system OpenMP library that can be

# linked to the Python interpreter, for instance via the libb2.so BLAKE2

# library that can itself be linked to an OpenMP runtime on Gentoo.

output = subprocess.check_output((sys.executable + " -m threadpoolctl").split())

results = json.loads(output.decode("utf-8"))

conda_prefix = os.getenv("CONDA_PREFIX")

managed_by_conda = conda_prefix and sys.executable.startswith(conda_prefix)

if not managed_by_conda: # pragma: no cover

# When using a Python interpreter that does not come from a conda

# environment, we should ignore any system OpenMP library.

results = [r for r in results if r["user_api"] != "openmp"]

assert results == []

def test_command_line_command_flag():

pytest.importorskip("numpy")

output = subprocess.check_output(

[sys.executable, "-m", "threadpoolctl", "-c", "import numpy"]

)

cli_info = json.loads(output.decode("utf-8"))

this_process_info = threadpool_info(debugging_info=True)

for lib_info in cli_info:

assert lib_info in this_process_info

def test_command_line_import_flag():

result = subprocess.run(

[

sys.executable,

"-m",

"threadpoolctl",

"-i",

"numpy",

"scipy.linalg",

"invalid_package",

"numpy.invalid_sumodule",

capture_output=True,

check=True,

encoding="utf-8",

)

cli_info = json.loads(result.stdout)

this_process_info = threadpool_info(debugging_info=True)

for lib_info in cli_info:

assert lib_info in this_process_info

warnings = [w.strip() for w in result.stderr.splitlines()]

assert "WARNING: could not import invalid_package" in warnings

assert "WARNING: could not import numpy.invalid_sumodule" in warnings

if scipy is None:

assert "WARNING: could not import scipy.linalg" in warnings

else:

assert "WARNING: could not import scipy.linalg" not in warnings

def test_architecture():

expected_openblas_architectures = (

# XXX: add more as needed by CI or developer laptops

"armv8",

"barcelona",

"cooperlake",

"haswell",

"neoversen1",

"prescott", # see: https://github.com/xianyi/OpenBLAS/pull/3485

"skylakex",

"sandybridge",

"vortex",

"zen",

)

expected_blis_architectures = (

# XXX: add more as needed by CI or developer laptops

"skx",

"haswell",

"zen3",

"generic",

)

for lib_info in threadpool_info():

if lib_info["internal_api"] == "openblas":

assert lib_info["architecture"].lower() in expected_openblas_architectures

elif lib_info["internal_api"] == "blis":

assert lib_info["architecture"].lower() in expected_blis_architectures

else:

# Not supported for other libraries

assert "architecture" not in lib_info

def test_openblas_threading_layer():

# Check that threadpool_info correctly recovers the threading layer used by openblas

openblas_controller = ThreadpoolController().select(internal_api="openblas")

if not (openblas_controller):

pytest.skip("requires OpenBLAS.")

expected_openblas_threading_layers = ("openmp", "pthreads", "disabled")

threading_layer = openblas_controller.lib_controllers[0].threading_layer

if threading_layer == "unknown":

# If we never recover an acceptable value for the threading layer, it will be

# always skipped and caught by check_no_test_always_skipped.

pytest.skip("Unknown OpenBLAS threading layer.")

assert threading_layer in expected_openblas_threading_layers

def run_in_thread(f, *args, **kwargs):

thread = Thread(target=lambda: f(*args, **kwargs))

thread.start()

thread.join()

def test_openblas_non_openmp_restricted_to_controlling_thread():

"""Only one thread can set number of threads for non-OpenMP OpenBLAS."""

openblas_controller = ThreadpoolController().select(internal_api="openblas")

if not (openblas_controller):

pytest.skip("requires OpenBLAS.")

for openblas_lib in openblas_controller.lib_controllers:

if openblas_lib.get_num_threads() > 1:

if openblas_lib.threading_layer == "openmp":

check_openblas_openmp_no_controlling_thread(openblas_lib)

else:

check_openblas_non_openmp_restricted_to_controlling_thread(openblas_lib)

def check_openblas_openmp_no_controlling_thread(openblas_lib):

orig_num_threads = openblas_lib.get_num_threads()

assert orig_num_threads > 1

# This thread can change num threads:

openblas_lib.set_num_threads(1)

assert openblas_lib.get_num_threads() == 1

# Another thread's attempts change _that_ thread:

result = []

def another_thread():

openblas_lib.set_num_threads(orig_num_threads)

result.append(openblas_lib.get_num_threads())

run_in_thread(another_thread)

assert result[-1] == orig_num_threads

# This thread is unchanged:

assert openblas_lib.get_num_threads() == 1

def check_openblas_non_openmp_restricted_to_controlling_thread(openblas_lib):

orig_num_threads = openblas_lib.get_num_threads()

assert orig_num_threads > 1

# This thread can change num threads:

openblas_lib.set_num_threads(1)

assert openblas_lib.get_num_threads() == 1

# Another thread's attempts are no-op:

result = []

def another_thread():

openblas_lib.set_num_threads(orig_num_threads)

result.append(openblas_lib.get_num_threads())

run_in_thread(another_thread)

assert result[-1] == 1

assert openblas_lib.get_num_threads() == 1

# This thread can still make changes:

openblas_lib.set_num_threads(orig_num_threads)

assert openblas_lib.get_num_threads() == orig_num_threads

# Another thread clearing the controlling thread has no effect:

def clear_and_set():

openblas_lib.clear_controlling_thread()

openblas_lib.set_num_threads(1)

run_in_thread(clear_and_set)

assert openblas_lib.get_num_threads() == orig_num_threads

# The controlling thread can clear, and then another thread can set:

openblas_lib.clear_controlling_thread()

run_in_thread(openblas_lib.set_num_threads, 1)

assert openblas_lib.get_num_threads() == 1

# Dead threads lose control:

openblas_lib.set_num_threads(orig_num_threads)

assert openblas_lib.get_num_threads() == orig_num_threads

# Release control:

openblas_lib.clear_controlling_thread()

# clear_controlling_thread(force=True) allows any thread to clear:

was_set, finish = Lock(), Lock()

was_set.acquire()

finish.acquire()

def set_and_exit_after_lock_released():

openblas_lib.set_num_threads(1)

was_set.release()

finish.acquire()

t = Thread(target=set_and_exit_after_lock_released)

t.start()

was_set.acquire()

assert openblas_lib.get_num_threads() == 1

# This thread can't set since it's not the controller:

openblas_lib.set_num_threads(orig_num_threads)

assert openblas_lib.get_num_threads() == 1

# But when forced clear happens, we can set:

openblas_lib.clear_controlling_thread(force=True)

openblas_lib.set_num_threads(orig_num_threads)

assert openblas_lib.get_num_threads() == orig_num_threads

# Clean up

finish.release()

t.join()

def _openblas_controlling_thread():

openblas_controller = ThreadpoolController().select(internal_api="openblas")

if not (openblas_controller):

pytest.skip("requires OpenBLAS.")

if {lc.threading_layer for lc in openblas_controller.lib_controllers} == {"openmp"}:

pytest.skip("require non-OpenMP OpenBLAS.")

return OpenBLASController._SHARED_STATE.controlling_thread

def test_openblas_controlling_thread_cleared_on_limiter_context_manager_exit():

with threadpool_limits(limits=1):

assert _openblas_controlling_thread() is current_thread()

with threadpool_limits(limits=1):

assert _openblas_controlling_thread() is current_thread()

assert _openblas_controlling_thread() is None

def test_openblas_controlling_thread_cleared_on_decorator_exit():

@threadpool_limits.wrap(limits=1)

def inner():

assert _openblas_controlling_thread() is current_thread()

@threadpool_limits.wrap(limits=1)

def outer():

assert _openblas_controlling_thread() is current_thread()

inner()

assert _openblas_controlling_thread() is current_thread()

outer()

assert _openblas_controlling_thread() is None

def test_openblas_controlling_thread_manual_increment_decrement_api(request):

limiter = ThreadpoolController().limit()

request.addfinalizer(limiter.restore_original_limits)

threadpool_limits(limits=1)

CONTROLLING_THREAD_OWNERSHIP.increment()

assert _openblas_controlling_thread() is current_thread()

threadpool_limits(limits=1)

CONTROLLING_THREAD_OWNERSHIP.increment()

assert _openblas_controlling_thread() is current_thread()

CONTROLLING_THREAD_OWNERSHIP.decrement()

assert _openblas_controlling_thread() is current_thread()

CONTROLLING_THREAD_OWNERSHIP.decrement()

assert _openblas_controlling_thread() is None

# skip test if not run in a azure pipelines job since it relies on a specific flexiblas

# installation.

@pytest.mark.skipif(

"GITHUB_ACTIONS" not in os.environ, reason="not running in azure pipelines"

)

def test_flexiblas():

# Check that threadpool_info correctly recovers the FlexiBLAS backends.

flexiblas_controller = ThreadpoolController().select(internal_api="flexiblas")

if not flexiblas_controller:

pytest.skip("requires FlexiBLAS.")

flexiblas_controller = flexiblas_controller.lib_controllers[0]

expected_backends = {"NETLIB", "OPENBLAS_CONDA"}

expected_backends_loaded = {"OPENBLAS_CONDA"}

expected_current_backend = "OPENBLAS_CONDA" # set as default at build time

flexiblas_backends = flexiblas_controller.available_backends

flexiblas_backends_loaded = flexiblas_controller.loaded_backends

current_backend = flexiblas_controller.current_backend

assert set(flexiblas_backends) == expected_backends

assert set(flexiblas_backends_loaded) == expected_backends_loaded

assert current_backend == expected_current_backend

def test_flexiblas_switch_error():

# Check that an error is raised when trying to switch to an invalid backend.

flexiblas_controller = ThreadpoolController().select(internal_api="flexiblas")

if not flexiblas_controller:

pytest.skip("requires FlexiBLAS.")

flexiblas_controller = flexiblas_controller.lib_controllers[0]

with pytest.raises(RuntimeError, match="Failed to load backend"):

flexiblas_controller.switch_backend("INVALID_BACKEND")

# skip test if not run in a azure pipelines job since it relies on a specific flexiblas

# installation.

@pytest.mark.skipif(

"GITHUB_ACTIONS" not in os.environ, reason="not running in azure pipelines"

)

def test_flexiblas_switch():

# Check that the backend can be switched.

controller = ThreadpoolController()

fb_controller = controller.select(internal_api="flexiblas")

if not fb_controller:

pytest.skip("requires FlexiBLAS.")

fb_controller = fb_controller.lib_controllers[0]

# at first mkl is not loaded in the CI jobs where this test runs

assert len(controller.select(internal_api="mkl").lib_controllers) == 0

# at first, only "OPENBLAS_CONDA" is loaded

assert fb_controller.current_backend == "OPENBLAS_CONDA"

assert fb_controller.loaded_backends == ["OPENBLAS_CONDA"]

cached_controller = get_cached_controller()

fb_controller.switch_backend("NETLIB")

assert fb_controller.current_backend == "NETLIB"

assert fb_controller.loaded_backends == ["OPENBLAS_CONDA", "NETLIB"]

# Switching invalidated the cached controller:

assert get_cached_controller() is not cached_controller

if sys.platform == "linux":

mkl_path = f"{os.getenv('CONDA_PREFIX')}/lib/libmkl_rt.so"

fb_controller.switch_backend(mkl_path)

assert fb_controller.current_backend == mkl_path

assert fb_controller.loaded_backends == ["OPENBLAS_CONDA", "NETLIB", mkl_path]

# switching the backend triggered a new search for loaded shared libs

assert len(controller.select(internal_api="mkl").lib_controllers) == 1

# switch back to default to avoid side effects

fb_controller.switch_backend("OPENBLAS_CONDA")

def test_threadpool_controller_as_decorator():

# Check that using the decorator can be nested and is restricted to the scope of

# the decorated function.

controller = ThreadpoolController()

original_info = controller.info()

if any(info["num_threads"] < 2 for info in original_info):

pytest.skip("Test requires at least 2 CPUs on host machine")

if not controller.select(user_api="blas"):

pytest.skip("Requires a blas runtime.")

def check_blas_num_threads(expected_num_threads):

blas_controller = ThreadpoolController().select(user_api="blas")

assert all(

lib_controller.num_threads == expected_num_threads

for lib_controller in blas_controller.lib_controllers

)

@controller.wrap(limits=1, user_api="blas")

def outer_func():

check_blas_num_threads(expected_num_threads=1)

inner_func()

check_blas_num_threads(expected_num_threads=1)

@controller.wrap(limits=2, user_api="blas")

def inner_func():

check_blas_num_threads(expected_num_threads=2)

outer_func()

assert ThreadpoolController().info() == original_info

def test_custom_controller():

# Check that a custom controller can be used to change the number of threads

# used by a library.

try:

import tests._pyMylib # noqa

except: # noqa: E722

pytest.skip("requires my_thread_lib to be compiled")

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