Fix pylint warnings / cleanup (#2218)

30 files changed, 146 insertions, 143 deletions

diff --git a/.github/workflows/issues.py b/.github/workflows/issues.py
index 2aea40be..06438b97 100644
--- a/.github/workflows/issues.py
+++ b/.github/workflows/issues.py
@@ -222,7 +222,7 @@ def add_label(issue, label):
     issue.add_to_labels(label)
 
 
-def _guess_labels_from_text(issue, text):
+def _guess_labels_from_text(text):
     assert isinstance(text, str), text
     for label, keywords in LABELS_MAP.items():
         for keyword in keywords:
@@ -232,7 +232,7 @@ def _guess_labels_from_text(issue, text):
 
 def add_labels_from_text(issue, text):
     assert isinstance(text, str), text
-    for label, keyword in _guess_labels_from_text(issue, text):
+    for label, keyword in _guess_labels_from_text(text):
         add_label(issue, label)
 
 
diff --git a/Makefile b/Makefile
index f5472bf4..27bba266 100644
--- a/Makefile
+++ b/Makefile
@@ -22,6 +22,7 @@ PY3_DEPS = \
 	flake8-quotes \
 	isort \
 	pep8-naming \
+	pylint \
 	pyperf \
 	pypinfo \
 	requests \
@@ -36,6 +37,7 @@ PY2_DEPS = \
 	mock
 PY_DEPS = `$(PYTHON) -c \
 	"import sys; print('$(PY3_DEPS)' if sys.version_info[0] == 3 else '$(PY2_DEPS)')"`
+NUM_WORKERS = `$(PYTHON) -c "import os; print(os.cpu_count() or 1)"`
 # "python3 setup.py build" can be parallelized on Python >= 3.6.
 BUILD_OPTS = `$(PYTHON) -c \
 	"import sys, os; \
@@ -191,10 +193,13 @@ test-coverage:  ## Run test coverage.
 # ===================================================================
 
 flake8:  ## Run flake8 linter.
-	@git ls-files '*.py' | xargs $(PYTHON) -m flake8 --config=.flake8
+	@git ls-files '*.py' | xargs $(PYTHON) -m flake8 --config=.flake8 --jobs=${NUM_WORKERS}
 
 isort:  ## Run isort linter.
-	@git ls-files '*.py' | xargs $(PYTHON) -m isort --check-only
+	@git ls-files '*.py' | xargs $(PYTHON) -m isort --check-only --jobs=${NUM_WORKERS}
+
+pylint:  ## Python pylint (not mandatory, just run it from time to time)
+	@git ls-files '*.py' | xargs $(PYTHON) -m pylint --rcfile=pyproject.toml --jobs=${NUM_WORKERS}
 
 c-linter:  ## Run C linter.
 	@git ls-files '*.c' '*.h' | xargs $(PYTHON) scripts/internal/clinter.py
@@ -209,11 +214,11 @@ lint-all:  ## Run all linters
 # ===================================================================
 
 fix-flake8:  ## Run autopep8, fix some Python flake8 / pep8 issues.
-	@git ls-files '*.py' | xargs $(PYTHON) -m autopep8 --in-place --jobs 0 --global-config=.flake8
-	@git ls-files '*.py' | xargs $(PYTHON) -m autoflake --in-place --jobs 0 --remove-all-unused-imports --remove-unused-variables --remove-duplicate-keys
+	@git ls-files '*.py' | xargs $(PYTHON) -m autopep8 --in-place --jobs=${NUM_WORKERS} --global-config=.flake8
+	@git ls-files '*.py' | xargs $(PYTHON) -m autoflake --in-place --jobs=${NUM_WORKERS} --remove-all-unused-imports --remove-unused-variables --remove-duplicate-keys
 
 fix-imports:  ## Fix imports with isort.
-	@git ls-files '*.py' | xargs $(PYTHON) -m isort
+	@git ls-files '*.py' | xargs $(PYTHON) -m isort --jobs=${NUM_WORKERS}
 
 fix-all:  ## Run all code fixers.
 	${MAKE} fix-flake8
diff --git a/psutil/__init__.py b/psutil/__init__.py
index deaf02ea..6036cbe9 100644
--- a/psutil/__init__.py
+++ b/psutil/__init__.py
@@ -516,7 +516,7 @@ class Process(object):
                     "s" if len(invalid_names) > 1 else "",
                     ", ".join(map(repr, invalid_names))))
 
-        retdict = dict()
+        retdict = {}
         ls = attrs or valid_names
         with self.oneshot():
             for name in ls:
diff --git a/psutil/_common.py b/psutil/_common.py
index 74ae2557..92286746 100644
--- a/psutil/_common.py
+++ b/psutil/_common.py
@@ -43,7 +43,7 @@ else:
 
 # can't take it from _common.py as this script is imported by setup.py
 PY3 = sys.version_info[0] == 3
-PSUTIL_DEBUG = bool(os.getenv('PSUTIL_DEBUG', 0))
+PSUTIL_DEBUG = bool(os.getenv('PSUTIL_DEBUG'))
 _DEFAULT = object()
 
 __all__ = [
@@ -924,7 +924,7 @@ def debug(msg):
     """If PSUTIL_DEBUG env var is set, print a debug message to stderr."""
     if PSUTIL_DEBUG:
         import inspect
-        fname, lineno, func_name, lines, index = inspect.getframeinfo(
+        fname, lineno, _, lines, index = inspect.getframeinfo(
             inspect.currentframe().f_back)
         if isinstance(msg, Exception):
             if isinstance(msg, (OSError, IOError, EnvironmentError)):
diff --git a/psutil/_compat.py b/psutil/_compat.py
index 52e762b1..2531cf4b 100644
--- a/psutil/_compat.py
+++ b/psutil/_compat.py
@@ -254,7 +254,7 @@ except ImportError:
         http://docs.python.org/3/library/functools.html#functools.lru_cache
         """
         def decorating_function(user_function):
-            cache = dict()
+            cache = {}
             stats = [0, 0]
             HITS, MISSES = 0, 1
             make_key = _make_key
@@ -432,7 +432,7 @@ except ImportError:
 try:
     from subprocess import TimeoutExpired as SubprocessTimeoutExpired
 except ImportError:
-    class SubprocessTimeoutExpired:
+    class SubprocessTimeoutExpired(Exception):
         pass
 
 
diff --git a/psutil/_psaix.py b/psutil/_psaix.py
index 2391478c..5c41069c 100644
--- a/psutil/_psaix.py
+++ b/psutil/_psaix.py
@@ -465,8 +465,8 @@ class Process(object):
 
     @wrap_exceptions
     def cpu_times(self):
-        cpu_times = cext.proc_cpu_times(self.pid, self._procfs_path)
-        return _common.pcputimes(*cpu_times)
+        t = cext.proc_cpu_times(self.pid, self._procfs_path)
+        return _common.pcputimes(*t)
 
     @wrap_exceptions
     def terminal(self):
diff --git a/psutil/_pslinux.py b/psutil/_pslinux.py
index 1bdeabfe..d178fe16 100644
--- a/psutil/_pslinux.py
+++ b/psutil/_pslinux.py
@@ -327,8 +327,8 @@ except ImportError:
                     pid, resource_, ctypes.byref(new), ctypes.byref(current))
 
             if ret != 0:
-                errno = ctypes.get_errno()
-                raise OSError(errno, os.strerror(errno))
+                errno_ = ctypes.get_errno()
+                raise OSError(errno_, os.strerror(errno_))
             return (current.rlim_cur, current.rlim_max)
 
 
@@ -1837,7 +1837,7 @@ class Process(object):
                 )
             except KeyError as err:
                 raise ValueError("%r field was not found in %s; found fields "
-                                 "are %r" % (err[0], fname, fields))
+                                 "are %r" % (err.args[0], fname, fields))
 
     @wrap_exceptions
     def cpu_times(self):
diff --git a/psutil/_pssunos.py b/psutil/_pssunos.py
index 541c1aa4..8663de3c 100644
--- a/psutil/_pssunos.py
+++ b/psutil/_pssunos.py
@@ -143,7 +143,7 @@ def swap_memory():
     p = subprocess.Popen(['/usr/bin/env', 'PATH=/usr/sbin:/sbin:%s' %
                           os.environ['PATH'], 'swap', '-l'],
                          stdout=subprocess.PIPE)
-    stdout, stderr = p.communicate()
+    stdout, _ = p.communicate()
     if PY3:
         stdout = stdout.decode(sys.stdout.encoding)
     if p.returncode != 0:
diff --git a/psutil/_pswindows.py b/psutil/_pswindows.py
index b546f15d..3802f3ed 100644
--- a/psutil/_pswindows.py
+++ b/psutil/_pswindows.py
@@ -699,7 +699,7 @@ def retry_error_partial_copy(fun):
     def wrapper(self, *args, **kwargs):
         delay = 0.0001
         times = 33
-        for x in range(times):  # retries for roughly 1 second
+        for _ in range(times):  # retries for roughly 1 second
             try:
                 return fun(self, *args, **kwargs)
             except WindowsError as _:
diff --git a/psutil/tests/__init__.py b/psutil/tests/__init__.py
index cdc8b671..e82bb38d 100644
--- a/psutil/tests/__init__.py
+++ b/psutil/tests/__init__.py
@@ -85,22 +85,19 @@ __all__ = [
     "HAS_CPU_AFFINITY", "HAS_CPU_FREQ", "HAS_ENVIRON", "HAS_PROC_IO_COUNTERS",
     "HAS_IONICE", "HAS_MEMORY_MAPS", "HAS_PROC_CPU_NUM", "HAS_RLIMIT",
     "HAS_SENSORS_BATTERY", "HAS_BATTERY", "HAS_SENSORS_FANS",
-    "HAS_SENSORS_TEMPERATURES", "HAS_MEMORY_FULL_INFO", "MACOS_11PLUS",
+    "HAS_SENSORS_TEMPERATURES", "MACOS_11PLUS",
     "MACOS_12PLUS", "COVERAGE",
     # subprocesses
     'pyrun', 'terminate', 'reap_children', 'spawn_testproc', 'spawn_zombie',
     'spawn_children_pair',
     # threads
-    'ThreadTask'
+    'ThreadTask',
     # test utils
     'unittest', 'skip_on_access_denied', 'skip_on_not_implemented',
     'retry_on_failure', 'TestMemoryLeak', 'PsutilTestCase',
     'process_namespace', 'system_namespace', 'print_sysinfo',
-    # install utils
-    'install_pip', 'install_test_deps',
     # fs utils
-    'chdir', 'safe_rmpath', 'create_exe', 'decode_path', 'encode_path',
-    'get_testfn',
+    'chdir', 'safe_rmpath', 'create_exe', 'get_testfn',
     # os
     'get_winver', 'kernel_version',
     # sync primitives
@@ -458,7 +455,7 @@ def spawn_zombie():
             zpid = int(conn.recv(1024))
             _pids_started.add(zpid)
             zombie = psutil.Process(zpid)
-            call_until(lambda: zombie.status(), "ret == psutil.STATUS_ZOMBIE")
+            call_until(zombie.status, "ret == psutil.STATUS_ZOMBIE")
             return (parent, zombie)
         finally:
             conn.close()
@@ -628,7 +625,7 @@ def reap_children(recursive=False):
     if children:
         for p in children:
             terminate(p, wait_timeout=None)
-        gone, alive = psutil.wait_procs(children, timeout=GLOBAL_TIMEOUT)
+        _, alive = psutil.wait_procs(children, timeout=GLOBAL_TIMEOUT)
         for p in alive:
             warn("couldn't terminate process %r; attempting kill()" % p)
             terminate(p, sig=signal.SIGKILL)
@@ -999,7 +996,7 @@ class TestMemoryLeak(PsutilTestCase):
     retries = 10 if CI_TESTING else 5
     verbose = True
     _thisproc = psutil.Process()
-    _psutil_debug_orig = bool(os.getenv('PSUTIL_DEBUG', 0))
+    _psutil_debug_orig = bool(os.getenv('PSUTIL_DEBUG'))
 
     @classmethod
     def setUpClass(cls):
@@ -1059,7 +1056,7 @@ class TestMemoryLeak(PsutilTestCase):
         diff = mem2 - mem1  # can also be negative
         return diff
 
-    def _check_mem(self, fun, times, warmup_times, retries, tolerance):
+    def _check_mem(self, fun, times, retries, tolerance):
         messages = []
         prev_mem = 0
         increase = times
@@ -1104,8 +1101,7 @@ class TestMemoryLeak(PsutilTestCase):
 
         self._call_ntimes(fun, warmup_times)  # warm up
         self._check_fds(fun)
-        self._check_mem(fun, times=times, warmup_times=warmup_times,
-                        retries=retries, tolerance=tolerance)
+        self._check_mem(fun, times=times, retries=retries, tolerance=tolerance)
 
     def execute_w_exc(self, exc, fun, **kwargs):
         """Convenience method to test a callable while making sure it
@@ -1122,7 +1118,6 @@ def print_sysinfo():
     import datetime
     import getpass
     import locale
-    import platform
     import pprint
     try:
         import pip
@@ -1616,7 +1611,7 @@ def check_net_address(addr, family):
     elif family == psutil.AF_LINK:
         assert re.match(r'([a-fA-F0-9]{2}[:|\-]?){6}', addr) is not None, addr
     else:
-        raise ValueError("unknown family %r", family)
+        raise ValueError("unknown family %r" % family)
 
 
 def check_connection_ntuple(conn):
diff --git a/psutil/tests/test_bsd.py b/psutil/tests/test_bsd.py
index e541547d..29ea384d 100755
--- a/psutil/tests/test_bsd.py
+++ b/psutil/tests/test_bsd.py
@@ -36,7 +36,7 @@ if BSD:
 
     PAGESIZE = getpagesize()
     # muse requires root privileges
-    MUSE_AVAILABLE = True if os.getuid() == 0 and which('muse') else False
+    MUSE_AVAILABLE = os.getuid() == 0 and which('muse')
 else:
     PAGESIZE = None
     MUSE_AVAILABLE = False
diff --git a/psutil/tests/test_connections.py b/psutil/tests/test_connections.py
index f3b1f837..d47233bc 100755
--- a/psutil/tests/test_connections.py
+++ b/psutil/tests/test_connections.py
@@ -501,7 +501,7 @@ class TestSystemWideConnections(ConnectionTestCase):
         pids = []
         times = 10
         fnames = []
-        for i in range(times):
+        for _ in range(times):
             fname = self.get_testfn()
             fnames.append(fname)
             src = textwrap.dedent("""\
diff --git a/psutil/tests/test_contracts.py b/psutil/tests/test_contracts.py
index 3b806ee3..b767e3eb 100755
--- a/psutil/tests/test_contracts.py
+++ b/psutil/tests/test_contracts.py
@@ -176,7 +176,7 @@ class TestAvailProcessAPIs(PsutilTestCase):
 
     def test_io_counters(self):
         hasit = hasattr(psutil.Process, "io_counters")
-        self.assertEqual(hasit, False if MACOS or SUNOS else True)
+        self.assertEqual(hasit, not (MACOS or SUNOS))
 
     def test_num_fds(self):
         self.assertEqual(hasattr(psutil.Process, "num_fds"), POSIX)
diff --git a/psutil/tests/test_linux.py b/psutil/tests/test_linux.py
index 964416b3..e1de6706 100755
--- a/psutil/tests/test_linux.py
+++ b/psutil/tests/test_linux.py
@@ -749,7 +749,7 @@ class TestSystemCPUCountLogical(PsutilTestCase):
             # this way we'll fall back on relying on /proc/stat
             with mock_open_content('/proc/cpuinfo', b"") as m:
                 self.assertEqual(psutil._pslinux.cpu_count_logical(), original)
-                m.called
+                assert m.called
 
 
 @unittest.skipIf(not LINUX, "LINUX only")
@@ -817,8 +817,8 @@ class TestSystemCPUFrequency(PsutilTestCase):
                 self.assertEqual(ret.max, 0.0)
                 self.assertEqual(ret.min, 0.0)
                 for freq in psutil.cpu_freq(percpu=True):
-                    self.assertEqual(ret.max, 0.0)
-                    self.assertEqual(ret.min, 0.0)
+                    self.assertEqual(freq.max, 0.0)
+                    self.assertEqual(freq.min, 0.0)
         finally:
             reload_module(psutil._pslinux)
             reload_module(psutil)
@@ -1057,7 +1057,7 @@ class TestSystemNetIOCounters(PsutilTestCase):
     def test_against_ifconfig(self):
         def ifconfig(nic):
             ret = {}
-            out = sh("ifconfig %s" % name)
+            out = sh("ifconfig %s" % nic)
             ret['packets_recv'] = int(
                 re.findall(r'RX packets[: ](\d+)', out)[0])
             ret['packets_sent'] = int(
@@ -1150,7 +1150,7 @@ class TestSystemDiskPartitions(PsutilTestCase):
 
         for part in psutil.disk_partitions(all=False):
             usage = psutil.disk_usage(part.mountpoint)
-            dev, total, used, free = df(part.mountpoint)
+            _, total, used, free = df(part.mountpoint)
             self.assertEqual(usage.total, total)
             self.assertAlmostEqual(usage.free, free,
                                    delta=TOLERANCE_DISK_USAGE)
@@ -2034,7 +2034,7 @@ class TestProcess(PsutilTestCase):
         # which no longer exists by the time we open() it (race
         # condition). threads() is supposed to ignore that instead
         # of raising NSP.
-        def open_mock(name, *args, **kwargs):
+        def open_mock_1(name, *args, **kwargs):
             if name.startswith('/proc/%s/task' % os.getpid()):
                 raise IOError(errno.ENOENT, "")
             else:
@@ -2042,20 +2042,20 @@ class TestProcess(PsutilTestCase):
 
         orig_open = open
         patch_point = 'builtins.open' if PY3 else '__builtin__.open'
-        with mock.patch(patch_point, side_effect=open_mock) as m:
+        with mock.patch(patch_point, side_effect=open_mock_1) as m:
             ret = psutil.Process().threads()
             assert m.called
             self.assertEqual(ret, [])
 
         # ...but if it bumps into something != ENOENT we want an
         # exception.
-        def open_mock(name, *args, **kwargs):
+        def open_mock_2(name, *args, **kwargs):
             if name.startswith('/proc/%s/task' % os.getpid()):
                 raise IOError(errno.EPERM, "")
             else:
                 return orig_open(name, *args, **kwargs)
 
-        with mock.patch(patch_point, side_effect=open_mock):
+        with mock.patch(patch_point, side_effect=open_mock_2):
             self.assertRaises(psutil.AccessDenied, psutil.Process().threads)
 
     def test_exe_mocked(self):
diff --git a/psutil/tests/test_misc.py b/psutil/tests/test_misc.py
index afa60b1c..a7b5d02d 100755
--- a/psutil/tests/test_misc.py
+++ b/psutil/tests/test_misc.py
@@ -299,19 +299,19 @@ class TestMemoizeDecorator(PsutilTestCase):
 
     def run_against(self, obj, expected_retval=None):
         # no args
-        for x in range(2):
+        for _ in range(2):
             ret = obj()
             self.assertEqual(self.calls, [((), {})])
             if expected_retval is not None:
                 self.assertEqual(ret, expected_retval)
         # with args
-        for x in range(2):
+        for _ in range(2):
             ret = obj(1)
             self.assertEqual(self.calls, [((), {}), ((1, ), {})])
             if expected_retval is not None:
                 self.assertEqual(ret, expected_retval)
         # with args + kwargs
-        for x in range(2):
+        for _ in range(2):
             ret = obj(1, bar=2)
             self.assertEqual(
                 self.calls, [((), {}), ((1, ), {}), ((1, ), {'bar': 2})])
@@ -400,19 +400,19 @@ class TestMemoizeDecorator(PsutilTestCase):
 
         calls = []
         # no args
-        for x in range(2):
+        for _ in range(2):
             ret = foo()
             expected = ((), {})
             self.assertEqual(ret, expected)
             self.assertEqual(len(calls), 1)
         # with args
-        for x in range(2):
+        for _ in range(2):
             ret = foo(1)
             expected = ((1, ), {})
             self.assertEqual(ret, expected)
             self.assertEqual(len(calls), 2)
         # with args + kwargs
-        for x in range(2):
+        for _ in range(2):
             ret = foo(1, bar=2)
             expected = ((1, ), {'bar': 2})
             self.assertEqual(ret, expected)
@@ -732,7 +732,7 @@ class TestWrapNumbers(PsutilTestCase):
             {'disk_io': {('disk1', 0): 0, ('disk1', 1): 0, ('disk1', 2): 100}})
         self.assertEqual(cache[2], {'disk_io': {'disk1': set([('disk1', 2)])}})
 
-        def assert_():
+        def check_cache_info():
             cache = wrap_numbers.cache_info()
             self.assertEqual(
                 cache[1],
@@ -746,14 +746,14 @@ class TestWrapNumbers(PsutilTestCase):
         wrap_numbers(input, 'disk_io')
         cache = wrap_numbers.cache_info()
         self.assertEqual(cache[0], {'disk_io': input})
-        assert_()
+        check_cache_info()
 
         # then it goes up
         input = {'disk1': nt(100, 100, 90)}
         wrap_numbers(input, 'disk_io')
         cache = wrap_numbers.cache_info()
         self.assertEqual(cache[0], {'disk_io': input})
-        assert_()
+        check_cache_info()
 
         # then it wraps again
         input = {'disk1': nt(100, 100, 20)}
@@ -837,7 +837,7 @@ class TestScripts(PsutilTestCase):
         return out
 
     @staticmethod
-    def assert_syntax(exe, args=None):
+    def assert_syntax(exe):
         exe = os.path.join(SCRIPTS_DIR, exe)
         if PY3:
             f = open(exe, 'rt', encoding='utf8')
diff --git a/psutil/tests/test_osx.py b/psutil/tests/test_osx.py
index af126484..dc0dd6ba 100755
--- a/psutil/tests/test_osx.py
+++ b/psutil/tests/test_osx.py
@@ -51,33 +51,6 @@ def vm_stat(field):
     return int(re.search(r'\d+', line).group(0)) * getpagesize()
 
 
-# http://code.activestate.com/recipes/578019/
-def human2bytes(s):
-    SYMBOLS = {
-        'customary': ('B', 'K', 'M', 'G', 'T', 'P', 'E', 'Z', 'Y'),
-    }
-    init = s
-    num = ""
-    while s and s[0:1].isdigit() or s[0:1] == '.':
-        num += s[0]
-        s = s[1:]
-    num = float(num)
-    letter = s.strip()
-    for name, sset in SYMBOLS.items():
-        if letter in sset:
-            break
-    else:
-        if letter == 'k':
-            sset = SYMBOLS['customary']
-            letter = letter.upper()
-        else:
-            raise ValueError("can't interpret %r" % init)
-    prefix = {sset[0]: 1}
-    for i, s in enumerate(sset[1:]):
-        prefix[s] = 1 << (i + 1) * 10
-    return int(num * prefix[letter])
-
-
 @unittest.skipIf(not MACOS, "MACOS only")
 class TestProcess(PsutilTestCase):
 
@@ -200,16 +173,6 @@ class TestSystemAPIs(PsutilTestCase):
         psutil_val = psutil.swap_memory().sout
         self.assertAlmostEqual(psutil_val, vmstat_val, delta=TOLERANCE_SYS_MEM)
 
-    # Not very reliable.
-    # def test_swapmem_total(self):
-    #     out = sh('sysctl vm.swapusage')
-    #     out = out.replace('vm.swapusage: ', '')
-    #     total, used, free = re.findall('\d+.\d+\w', out)
-    #     psutil_smem = psutil.swap_memory()
-    #     self.assertEqual(psutil_smem.total, human2bytes(total))
-    #     self.assertEqual(psutil_smem.used, human2bytes(used))
-    #     self.assertEqual(psutil_smem.free, human2bytes(free))
-
     # --- network
 
     def test_net_if_stats(self):
diff --git a/psutil/tests/test_posix.py b/psutil/tests/test_posix.py
index d8732230..0dc1dfda 100755
--- a/psutil/tests/test_posix.py
+++ b/psutil/tests/test_posix.py
@@ -63,6 +63,8 @@ def ps(fmt, pid=None):
             cmd.append('ax')
 
     if SUNOS:
+        # XXX: set() has not get() method so this cannot work; not sure
+        # what I meant in here.
         fmt_map = set(('command', 'comm', 'start', 'stime'))
         fmt = fmt_map.get(fmt, fmt)
 
@@ -408,8 +410,7 @@ class TestSystemAPIs(PsutilTestCase):
                         "raw devices not supported" in err or \
                         "permission denied" in err:
                     continue
-                else:
-                    raise
+                raise
             else:
                 self.assertAlmostEqual(usage.total, total, delta=tolerance)
                 self.assertAlmostEqual(usage.used, used, delta=tolerance)
diff --git a/psutil/tests/test_process.py b/psutil/tests/test_process.py
index df6a84c3..ec15ffda 100755
--- a/psutil/tests/test_process.py
+++ b/psutil/tests/test_process.py
@@ -231,7 +231,7 @@ class TestProcess(PsutilTestCase):
         p = psutil.Process()
         p.cpu_percent(interval=0.001)
         p.cpu_percent(interval=0.001)
-        for x in range(100):
+        for _ in range(100):
             percent = p.cpu_percent(interval=None)
             self.assertIsInstance(percent, float)
             self.assertGreaterEqual(percent, 0.0)
@@ -611,8 +611,7 @@ class TestProcess(PsutilTestCase):
     def test_memory_maps(self):
         p = psutil.Process()
         maps = p.memory_maps()
-        paths = [x for x in maps]
-        self.assertEqual(len(paths), len(set(paths)))
+        self.assertEqual(len(maps), len(set(maps)))
         ext_maps = p.memory_maps(grouped=False)
 
         for nt in maps:
@@ -1035,7 +1034,7 @@ class TestProcess(PsutilTestCase):
     def test_num_ctx_switches(self):
         p = psutil.Process()
         before = sum(p.num_ctx_switches())
-        for x in range(500000):
+        for _ in range(500000):
             after = sum(p.num_ctx_switches())
             if after > before:
                 return
@@ -1147,7 +1146,7 @@ class TestProcess(PsutilTestCase):
     def test_suspend_resume(self):
         p = self.spawn_psproc()
         p.suspend()
-        for x in range(100):
+        for _ in range(100):
             if p.status() == psutil.STATUS_STOPPED:
                 break
             time.sleep(0.01)
diff --git a/psutil/tests/test_system.py b/psutil/tests/test_system.py
index 1722b515..c2b1df84 100755
--- a/psutil/tests/test_system.py
+++ b/psutil/tests/test_system.py
@@ -123,7 +123,7 @@ class TestProcessAPIs(PsutilTestCase):
             self.assertFalse(hasattr(p, 'returncode'))
 
         @retry_on_failure(30)
-        def test(procs, callback):
+        def test_1(procs, callback):
             gone, alive = psutil.wait_procs(procs, timeout=0.03,
                                             callback=callback)
             self.assertEqual(len(gone), 1)
@@ -131,7 +131,7 @@ class TestProcessAPIs(PsutilTestCase):
             return gone, alive
 
         sproc3.terminate()
-        gone, alive = test(procs, callback)
+        gone, alive = test_1(procs, callback)
         self.assertIn(sproc3.pid, [x.pid for x in gone])
         if POSIX:
             self.assertEqual(gone.pop().returncode, -signal.SIGTERM)
@@ -142,7 +142,7 @@ class TestProcessAPIs(PsutilTestCase):
             self.assertFalse(hasattr(p, 'returncode'))
 
         @retry_on_failure(30)
-        def test(procs, callback):
+        def test_2(procs, callback):
             gone, alive = psutil.wait_procs(procs, timeout=0.03,
                                             callback=callback)
             self.assertEqual(len(gone), 3)
@@ -151,7 +151,7 @@ class TestProcessAPIs(PsutilTestCase):
 
         sproc1.terminate()
         sproc2.terminate()
-        gone, alive = test(procs, callback)
+        gone, alive = test_2(procs, callback)
         self.assertEqual(set(pids), set([sproc1.pid, sproc2.pid, sproc3.pid]))
         for p in gone:
             self.assertTrue(hasattr(p, 'returncode'))
@@ -165,7 +165,7 @@ class TestProcessAPIs(PsutilTestCase):
         procs = [psutil.Process(x.pid) for x in (sproc1, sproc2, sproc3)]
         for p in procs:
             p.terminate()
-        gone, alive = psutil.wait_procs(procs)
+        psutil.wait_procs(procs)
 
     def test_pid_exists(self):
         sproc = self.spawn_testproc()
@@ -449,7 +449,7 @@ class TestCpuAPIs(PsutilTestCase):
 
     def test_cpu_percent(self):
         last = psutil.cpu_percent(interval=0.001)
-        for x in range(100):
+        for _ in range(100):
             new = psutil.cpu_percent(interval=None)
             self._test_cpu_percent(new, last, new)
             last = new
@@ -459,7 +459,7 @@ class TestCpuAPIs(PsutilTestCase):
     def test_per_cpu_percent(self):
         last = psutil.cpu_percent(interval=0.001, percpu=True)
         self.assertEqual(len(last), psutil.cpu_count())
-        for x in range(100):
+        for _ in range(100):
             new = psutil.cpu_percent(interval=None, percpu=True)
             for percent in new:
                 self._test_cpu_percent(percent, last, new)
@@ -469,7 +469,7 @@ class TestCpuAPIs(PsutilTestCase):
 
     def test_cpu_times_percent(self):
         last = psutil.cpu_times_percent(interval=0.001)
-        for x in range(100):
+        for _ in range(100):
             new = psutil.cpu_times_percent(interval=None)
             for percent in new:
                 self._test_cpu_percent(percent, last, new)
@@ -481,7 +481,7 @@ class TestCpuAPIs(PsutilTestCase):
     def test_per_cpu_times_percent(self):
         last = psutil.cpu_times_percent(interval=0.001, percpu=True)
         self.assertEqual(len(last), psutil.cpu_count())
-        for x in range(100):
+        for _ in range(100):
             new = psutil.cpu_times_percent(interval=None, percpu=True)
             for cpu in new:
                 for percent in cpu:
diff --git a/psutil/tests/test_testutils.py b/psutil/tests/test_testutils.py
index e757e017..77e52b69 100755
--- a/psutil/tests/test_testutils.py
+++ b/psutil/tests/test_testutils.py
@@ -406,16 +406,16 @@ class TestMemLeakClass(TestMemoryLeak):
         self.assertEqual(len(ls), times + 1)
 
     def test_execute_w_exc(self):
-        def fun():
+        def fun_1():
             1 / 0
-        self.execute_w_exc(ZeroDivisionError, fun)
+        self.execute_w_exc(ZeroDivisionError, fun_1)
         with self.assertRaises(ZeroDivisionError):
-            self.execute_w_exc(OSError, fun)
+            self.execute_w_exc(OSError, fun_1)
 
-        def fun():
+        def fun_2():
             pass
         with self.assertRaises(AssertionError):
-            self.execute_w_exc(ZeroDivisionError, fun)
+            self.execute_w_exc(ZeroDivisionError, fun_2)
 
 
 class TestTestingUtils(PsutilTestCase):
diff --git a/psutil/tests/test_unicode.py b/psutil/tests/test_unicode.py
index 3fa3f017..43cf2b49 100755
--- a/psutil/tests/test_unicode.py
+++ b/psutil/tests/test_unicode.py
@@ -316,8 +316,7 @@ class TestFSAPIsWithInvalidPath(TestFSAPIs):
     """Test FS APIs with a funky, invalid path name."""
     funky_suffix = INVALID_UNICODE_SUFFIX
 
-    @classmethod
-    def expect_exact_path_match(cls):
+    def expect_exact_path_match(self):
         # Invalid unicode names are supposed to work on Python 2.
         return True
 
diff --git a/pyproject.toml b/pyproject.toml
index c8cb62af..8d68131c 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -34,6 +34,44 @@ exclude_lines = [
     "raise NotImplementedError",
 ]
 
+[tool.pylint.messages_control]
+# Important ones:
+# undefined-all-variable, invalid-envvar-default, reimported, raising-format-tuple, simplifiable-if-expression, useless-object-inheritance
+disable = [
+    "broad-except",  # except Exception:
+    "consider-using-dict-comprehension",
+    "consider-using-f-string",
+    "consider-using-set-comprehension",
+    "consider-using-with",
+    "disallowed-name",
+    "fixme",
+    "global-statement",
+    "import-error",
+    "import-outside-toplevel",
+    "inconsistent-return-statements",
+    "invalid-name",
+    "missing-class-docstring",
+    "missing-function-docstring",
+    "no-else-raise",
+    "no-else-return",
+    "protected-access",
+    "raise-missing-from",
+    "redefined-builtin",
+    "super-with-arguments",
+    "too-few-public-methods",
+    "too-many-arguments",
+    "too-many-branches",
+    "too-many-instance-attributes",
+    "too-many-lines",
+    "too-many-locals",
+    "too-many-public-methods",
+    "too-many-return-statements",
+    "too-many-statements",
+    "ungrouped-imports",
+    "unspecified-encoding",
+    "wrong-import-position",
+]
+
 [build-system]
 requires = ["setuptools>=43", "wheel"]
 build-backend = "setuptools.build_meta"
diff --git a/scripts/internal/download_wheels_appveyor.py b/scripts/internal/download_wheels_appveyor.py
index d69ace62..dcded559 100755
--- a/scripts/internal/download_wheels_appveyor.py
+++ b/scripts/internal/download_wheels_appveyor.py
@@ -101,9 +101,9 @@ def run():
     # 2 wheels (32 and 64 bit) per supported python version
     expected = len(PY_VERSIONS) * 2
     if expected != completed:
-        return exit("expected %s files, got %s" % (expected, completed))
+        return sys.exit("expected %s files, got %s" % (expected, completed))
     if exc:
-        return exit()
+        return sys.exit()
     rename_win27_wheels()
 
 
diff --git a/scripts/internal/git_pre_commit.py b/scripts/internal/git_pre_commit.py
index 87783627..dad0066b 100755
--- a/scripts/internal/git_pre_commit.py
+++ b/scripts/internal/git_pre_commit.py
@@ -107,16 +107,16 @@ def main():
             # space at end of line
             if line.endswith(' '):
                 print("%s:%s %r" % (path, lineno, line))
-                return exit("space at end of line")
+                return sys.exit("space at end of line")
             line = line.rstrip()
             # # pdb (now provided by flake8-debugger plugin)
             # if "pdb.set_trace" in line:
             #     print("%s:%s %s" % (path, lineno, line))
-            #     return exit("you forgot a pdb in your python code")
+            #     return sys.exit("you forgot a pdb in your python code")
             # # bare except clause (now provided by flake8-blind-except plugin)
             # if "except:" in line and not line.endswith("# NOQA"):
             #     print("%s:%s %s" % (path, lineno, line))
-            #     return exit("bare except clause")
+            #     return sys.exit("bare except clause")
 
     # Python linters
     if py_files:
@@ -125,28 +125,28 @@ def main():
         cmd = "%s -m flake8 --config=.flake8 %s" % (PYTHON, " ".join(py_files))
         ret = subprocess.call(shlex.split(cmd))
         if ret != 0:
-            return exit("python code didn't pass 'flake8' style check; "
-                        "try running 'make fix-flake8'")
+            return sys.exit("python code didn't pass 'flake8' style check; "
+                            "try running 'make fix-flake8'")
         # isort
         cmd = "%s -m isort --check-only %s" % (
             PYTHON, " ".join(py_files))
         ret = subprocess.call(shlex.split(cmd))
         if ret != 0:
-            return exit("python code didn't pass 'isort' style check; "
-                        "try running 'make fix-imports'")
+            return sys.exit("python code didn't pass 'isort' style check; "
+                            "try running 'make fix-imports'")
     # C linter
     if c_files:
         # XXX: we should escape spaces and possibly other amenities here
         cmd = "%s scripts/internal/clinter.py %s" % (PYTHON, " ".join(c_files))
         ret = subprocess.call(cmd, shell=True)
         if ret != 0:
-            return exit("C code didn't pass style check")
+            return sys.exit("C code didn't pass style check")
     if new_rm_mv:
         out = sh("%s scripts/internal/generate_manifest.py" % PYTHON)
         with open_text('MANIFEST.in') as f:
             if out.strip() != f.read().strip():
-                exit("some files were added, deleted or renamed; "
-                     "run 'make generate-manifest' and commit again")
+                sys.exit("some files were added, deleted or renamed; "
+                         "run 'make generate-manifest' and commit again")
 
 
 main()
diff --git a/scripts/internal/print_announce.py b/scripts/internal/print_announce.py
index c2113f36..510dc15f 100755
--- a/scripts/internal/print_announce.py
+++ b/scripts/internal/print_announce.py
@@ -89,7 +89,7 @@ def get_changes():
             break
     lines.pop(0)
 
-    for i, line in enumerate(lines):
+    for line in lines:
         line = lines.pop(0)
         line = line.rstrip()
         if re.match(r"^- \d+_", line):
diff --git a/scripts/internal/print_dist.py b/scripts/internal/print_dist.py
index 492bed1c..978e50e2 100755
--- a/scripts/internal/print_dist.py
+++ b/scripts/internal/print_dist.py
@@ -98,7 +98,7 @@ def main():
         elif path.endswith(".tar.gz"):
             pkg = Tarball(path)
         else:
-            raise ValueError("invalid package %r", path)
+            raise ValueError("invalid package %r" % path)
         groups[pkg.platform()].append(pkg)
 
     tot_files = 0
diff --git a/scripts/internal/winmake.py b/scripts/internal/winmake.py
index 466887c2..16de3908 100755
--- a/scripts/internal/winmake.py
+++ b/scripts/internal/winmake.py
@@ -82,7 +82,7 @@ DEFAULT_COLOR = 7
 # ===================================================================
 
 
-def safe_print(text, file=sys.stdout, flush=False):
+def safe_print(text, file=sys.stdout):
     """Prints a (unicode) string to the console, encoded depending on
     the stdout/file encoding (eg. cp437 on Windows). This is to avoid
     encoding errors in case of funky path names.
@@ -228,7 +228,7 @@ def build():
     # order to allow "import psutil" when using the interactive interpreter
     # from within psutil root directory.
     cmd = [PYTHON, "setup.py", "build_ext", "-i"]
-    if sys.version_info[:2] >= (3, 6) and os.cpu_count() or 1 > 1:
+    if sys.version_info[:2] >= (3, 6) and (os.cpu_count() or 1) > 1:
         cmd += ['--parallel', str(os.cpu_count())]
     # Print coloured warnings in real time.
     p = subprocess.Popen(cmd, stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
@@ -547,8 +547,7 @@ def get_python(path):
             return pypath
 
 
-def main():
-    global PYTHON
+def parse_args():
     parser = argparse.ArgumentParser()
     # option shared by all commands
     parser.add_argument(
@@ -587,8 +586,19 @@ def main():
 
     for p in (test, test_by_name):
         p.add_argument('arg', type=str, nargs='?', default="", help="arg")
+
     args = parser.parse_args()
 
+    if not args.command or args.command == 'help':
+        parser.print_help(sys.stderr)
+        sys.exit(1)
+
+    return args
+
+
+def main():
+    global PYTHON
+    args = parse_args()
     # set python exe
     PYTHON = get_python(args.python)
     if not PYTHON:
@@ -597,10 +607,6 @@ def main():
     os.putenv('PYTHON', PYTHON)
     win_colorprint("using " + PYTHON)
 
-    if not args.command or args.command == 'help':
-        parser.print_help(sys.stderr)
-        sys.exit(1)
-
     fname = args.command.replace('-', '_')
     fun = getattr(sys.modules[__name__], fname)  # err if fun not defined
     funargs = []
diff --git a/scripts/iotop.py b/scripts/iotop.py
index f4d62d46..07ae2fa3 100755
--- a/scripts/iotop.py
+++ b/scripts/iotop.py
@@ -71,7 +71,7 @@ def poll(interval):
     sorted by IO activity and total disks I/O activity.
     """
     # first get a list of all processes and disk io counters
-    procs = [p for p in psutil.process_iter()]
+    procs = list(psutil.process_iter())
     for p in procs[:]:
         try:
             p._before = p.io_counters()
diff --git a/scripts/procinfo.py b/scripts/procinfo.py
index 743a1777..fd44c83e 100755
--- a/scripts/procinfo.py
+++ b/scripts/procinfo.py
@@ -316,7 +316,7 @@ def run(pid, verbose=False):
             print_("", template % (bytes2human(region.rss), region.path))
 
 
-def main(argv=None):
+def main():
     parser = argparse.ArgumentParser(
         description="print information about a process")
     parser.add_argument("pid", type=int, help="process pid", nargs='?')
diff --git a/setup.py b/setup.py
index 65dad252..4e6f6f17 100755
--- a/setup.py
+++ b/setup.py
@@ -346,10 +346,7 @@ if POSIX:
             # for an explanation of Solaris /etc/release
             with open('/etc/release') as f:
                 update = re.search(r'(?<=s10s_u)[0-9]{1,2}', f.readline())
-                if update is None:
-                    return 0
-                else:
-                    return int(update.group(0))
+                return int(update.group(0)) if update else 0
 
         posix_extension.libraries.append('socket')
         if platform.release() == '5.10':