multi: Fallback to os.cpu_count() on non UNIX OSes

`os.sched_getaffinity()` is the only method in the StdLib that correctly
handles `taskset` restrictions etc. Nevertheless, it is only defined on
Linux. Therefore, on different OSes we fall back to `cpu_count()` and if
that is not available, we set `MAX_AVAILABLE_PROCESSES = 1`.

Further info:

    https://stackoverflow.com/questions/1006289/how-to-find-out-the-number-of-cpus-using-python

Fixes #35

requirements/requirements-dev.txt

@@ -37,7 +37,7 @@ html5lib==1.1; (python_version >= "2.7" and python_full_version < "3.0.0") or (p
 identify==2.5.1; python_version >= "3.7"
 idna==3.3; python_version >= "3.7" and python_version < "4"
 imagesize==1.3.0; python_version >= "3.6" and python_full_version < "3.0.0" or python_full_version >= "3.4.0" and python_version >= "3.6"
-importlib-metadata==4.11.4; python_version < "3.10" and python_version >= "3.7" and (python_version >= "3.6" and python_full_version < "3.0.0" or python_full_version >= "3.4.0" and python_version >= "3.6")
+importlib-metadata==4.12.0; python_version < "3.10" and python_version >= "3.7" and (python_version >= "3.6" and python_full_version < "3.0.0" or python_full_version >= "3.4.0" and python_version >= "3.6")
 iniconfig==1.1.1; python_version >= "3.7"
 ipykernel==6.15.0; python_version >= "3.7"
 ipython==8.4.0; python_version >= "3.8"
@@ -60,7 +60,7 @@ munch==2.5.0; python_version >= "3.7"
 mypy-extensions==0.4.3; python_version >= "3.6"
 mypy==0.950; python_version >= "3.6"
 nest-asyncio==1.5.5; python_version >= "3.7"
-nodeenv==1.6.0; python_version >= "3.7"
+nodeenv==1.7.0; python_version >= "3.7" and python_full_version < "3.0.0" or python_full_version >= "3.7.0" and python_version >= "3.7"
 numpy==1.23.0
 packaging==21.3; python_version >= "3.8" and python_version < "4.0" and (python_version >= "3.6" and python_full_version < "3.0.0" or python_full_version >= "3.4.0" and python_version >= "3.6")
 pandas==1.4.3; python_version >= "3.8"
@@ -71,7 +71,7 @@ pickleshare==0.7.5; python_version >= "3.8"
 platformdirs==2.5.2; python_full_version >= "3.7.2" and python_version >= "3.7" and python_version < "4.0"
 pluggy==1.0.0; python_version >= "3.7"
 pre-commit==2.19.0; python_version >= "3.7"
-prompt-toolkit==3.0.29; python_full_version >= "3.6.2" and python_version >= "3.8"
+prompt-toolkit==3.0.30; python_full_version >= "3.6.2" and python_version >= "3.8"
 prospector==1.7.7; python_full_version >= "3.6.2" and python_version < "4.0"
 psutil==5.9.1; python_version >= "3.7" and python_full_version < "3.0.0" or python_full_version >= "3.4.0" and python_version >= "3.7"
 ptyprocess==0.7.0; sys_platform != "win32" and python_version >= "3.8"
@@ -123,12 +123,12 @@ tornado==6.1; python_version >= "3.7"
 tqdm==4.64.0; (python_version >= "2.7" and python_full_version < "3.0.0") or (python_full_version >= "3.4.0")
 traitlets==5.3.0; python_version >= "3.8"
 typepigeon==1.0.14; python_version >= "3.6" and python_version < "4.0"
-types-requests==2.27.31
+types-requests==2.28.0
 types-urllib3==1.26.15
 typing-extensions==4.2.0; python_version >= "3.7" and python_full_version >= "3.7.2" and python_version < "3.10"
 urllib3==1.26.9; python_version >= "3.7" and python_full_version < "3.0.0" and python_version < "4" or python_full_version >= "3.5.0" and python_version < "4" and python_version >= "3.7"
 vcrpy==4.1.1; python_version >= "3.5"
-virtualenv==20.14.1; python_version >= "3.7" and python_full_version < "3.0.0" or python_full_version >= "3.5.0" and python_version >= "3.7"
+virtualenv==20.15.0; python_version >= "3.7" and python_full_version < "3.0.0" or python_full_version >= "3.5.0" and python_version >= "3.7"
 wcwidth==0.2.5; python_full_version >= "3.6.2" and python_version >= "3.8"
 webencodings==0.5.1; python_version >= "2.7" and python_full_version < "3.0.0" or python_full_version >= "3.5.0"
 wrapt==1.14.1; python_full_version >= "3.7.2" and python_version >= "3.7" and python_version < "4.0"

searvey/multi.py

@@ -28,7 +28,12 @@
 
 
 # https://docs.python.org/3/library/os.html#os.cpu_count
-MAX_AVAILABLE_PROCESSES = len(os.sched_getaffinity(0))
+try:
+    MAX_AVAILABLE_PROCESSES = len(os.sched_getaffinity(0))
+except AttributeError:
+    MAX_AVAILABLE_PROCESSES = os.cpu_count()
+    if MAX_AVAILABLE_PROCESSES is None:
+        MAX_AVAILABLE_PROCESSES = 1
 
 
 class FutureResult(pydantic.BaseModel):