Revert "Merge pull request #560 from utapyngo/logical-cpu-count"

This reverts commit 0094b29a14, reversing
changes made to c6255faad4.

setup.py

@@ -1,6 +1,6 @@
 from setuptools import setup, find_packages
 
-install_requires = ["execnet>=1.1", "psutil>=3.0.0", "pytest>=6.0.0", "pytest-forked"]
+install_requires = ["execnet>=1.1", "pytest>=6.0.0", "pytest-forked"]
 
 
 with open("README.rst") as f:

src/xdist/plugin.py

@@ -1,12 +1,31 @@
+import os
 import uuid
 
-import psutil
 import py
 import pytest
 
 
 def auto_detect_cpus():
-    return psutil.cpu_count(logical=False) or psutil.cpu_count() or 1
+    try:
+        from os import sched_getaffinity
+    except ImportError:
+        if os.environ.get("TRAVIS") == "true":
+            # workaround https://bitbucket.org/pypy/pypy/issues/2375
+            return 2
+        try:
+            from os import cpu_count
+        except ImportError:
+            from multiprocessing import cpu_count
+    else:
+
+        def cpu_count():
+            return len(sched_getaffinity(0))
+
+    try:
+        n = cpu_count()
+    except NotImplementedError:
+        return 1
+    return n if n else 1
 
 
 class AutoInt(int):

testing/test_plugin.py

@@ -35,10 +35,17 @@ def test_dist_options(testdir):
 
 
 def test_auto_detect_cpus(testdir, monkeypatch):
-    import psutil
+    import os
     from xdist.plugin import pytest_cmdline_main as check_options
 
-    monkeypatch.setattr(psutil, "cpu_count", lambda logical=True: 99)
+    if hasattr(os, "sched_getaffinity"):
+        monkeypatch.setattr(os, "sched_getaffinity", lambda _pid: set(range(99)))
+    elif hasattr(os, "cpu_count"):
+        monkeypatch.setattr(os, "cpu_count", lambda: 99)
+    else:
+        import multiprocessing
+
+        monkeypatch.setattr(multiprocessing, "cpu_count", lambda: 99)
 
     config = testdir.parseconfigure("-n2")
     assert config.getoption("numprocesses") == 2
@@ -52,9 +59,10 @@ def test_auto_detect_cpus(testdir, monkeypatch):
     assert config.getoption("numprocesses") == 0
     assert config.getoption("dist") == "no"
 
-    monkeypatch.setattr(psutil, "cpu_count", lambda logical=True: None)
+    monkeypatch.delattr(os, "sched_getaffinity", raising=False)
+    monkeypatch.setenv("TRAVIS", "true")
     config = testdir.parseconfigure("-nauto")
-    assert config.getoption("numprocesses") == 1
+    assert config.getoption("numprocesses") == 2
 
 
 def test_boxed_with_collect_only(testdir):