bpo-34060: Report system load when running test suite for Windows (GH… · python/cpython@e16467a (original) (raw)
``
1
`+
import subprocess
`
``
2
`+
import sys
`
``
3
`+
import os
`
``
4
`+
import _winapi
`
``
5
`+
import msvcrt
`
``
6
`+
import uuid
`
``
7
`+
from test import support
`
``
8
+
``
9
+
``
10
`+
Max size of asynchronous reads
`
``
11
`+
BUFSIZE = 8192
`
``
12
`+
Exponential damping factor (see below)
`
``
13
`+
LOAD_FACTOR_1 = 0.9200444146293232478931553241
`
``
14
`+
Seconds per measurement
`
``
15
`+
SAMPLING_INTERVAL = 5
`
``
16
`+
COUNTER_NAME = r'\System\Processor Queue Length'
`
``
17
+
``
18
+
``
19
`+
class WindowsLoadTracker():
`
``
20
`+
"""
`
``
21
`` +
This class asynchronously interacts with the typeperf command to read
``
``
22
`+
the system load on Windows. Mulitprocessing and threads can't be used
`
``
23
`+
here because they interfere with the test suite's cases for those
`
``
24
`+
modules.
`
``
25
`+
"""
`
``
26
+
``
27
`+
def init(self):
`
``
28
`+
self.load = 0.0
`
``
29
`+
self.start()
`
``
30
+
``
31
`+
def start(self):
`
``
32
`+
Create a named pipe which allows for asynchronous IO in Windows
`
``
33
`+
pipe_name = r'\.\pipe\typeperf_output_' + str(uuid.uuid4())
`
``
34
+
``
35
`+
open_mode = _winapi.PIPE_ACCESS_INBOUND
`
``
36
`+
open_mode |= _winapi.FILE_FLAG_FIRST_PIPE_INSTANCE
`
``
37
`+
open_mode |= _winapi.FILE_FLAG_OVERLAPPED
`
``
38
+
``
39
`+
This is the read end of the pipe, where we will be grabbing output
`
``
40
`+
self.pipe = _winapi.CreateNamedPipe(
`
``
41
`+
pipe_name, open_mode, _winapi.PIPE_WAIT,
`
``
42
`+
1, BUFSIZE, BUFSIZE, _winapi.NMPWAIT_WAIT_FOREVER, _winapi.NULL
`
``
43
`+
)
`
``
44
`+
The write end of the pipe which is passed to the created process
`
``
45
`+
pipe_write_end = _winapi.CreateFile(
`
``
46
`+
pipe_name, _winapi.GENERIC_WRITE, 0, _winapi.NULL,
`
``
47
`+
_winapi.OPEN_EXISTING, 0, _winapi.NULL
`
``
48
`+
)
`
``
49
`+
Open up the handle as a python file object so we can pass it to
`
``
50
`+
subprocess
`
``
51
`+
command_stdout = msvcrt.open_osfhandle(pipe_write_end, 0)
`
``
52
+
``
53
`+
Connect to the read end of the pipe in overlap/async mode
`
``
54
`+
overlap = _winapi.ConnectNamedPipe(self.pipe, overlapped=True)
`
``
55
`+
overlap.GetOverlappedResult(True)
`
``
56
+
``
57
`+
Spawn off the load monitor
`
``
58
`+
command = ['typeperf', COUNTER_NAME, '-si', str(SAMPLING_INTERVAL)]
`
``
59
`+
self.p = subprocess.Popen(command, stdout=command_stdout, cwd=support.SAVEDCWD)
`
``
60
+
``
61
`+
Close our copy of the write end of the pipe
`
``
62
`+
os.close(command_stdout)
`
``
63
+
``
64
`+
def del(self):
`
``
65
`+
self.p.kill()
`
``
66
`+
self.p.wait()
`
``
67
+
``
68
`+
def read_output(self):
`
``
69
`+
import _winapi
`
``
70
+
``
71
`+
overlapped, _ = _winapi.ReadFile(self.pipe, BUFSIZE, True)
`
``
72
`+
bytes_read, res = overlapped.GetOverlappedResult(False)
`
``
73
`+
if res != 0:
`
``
74
`+
return
`
``
75
+
``
76
`+
return overlapped.getbuffer().decode()
`
``
77
+
``
78
`+
def getloadavg(self):
`
``
79
`+
typeperf_output = self.read_output()
`
``
80
`+
Nothing to update, just return the current load
`
``
81
`+
if not typeperf_output:
`
``
82
`+
return self.load
`
``
83
+
``
84
`+
Process the backlog of load values
`
``
85
`+
for line in typeperf_output.splitlines():
`
``
86
`+
typeperf outputs in a CSV format like this:
`
``
87
`+
"07/19/2018 01:32:26.605","3.000000"
`
``
88
`+
toks = line.split(',')
`
``
89
`+
Ignore blank lines and the initial header
`
``
90
`+
if line.strip() == '' or (COUNTER_NAME in line) or len(toks) != 2:
`
``
91
`+
continue
`
``
92
+
``
93
`+
load = float(toks[1].replace('"', ''))
`
``
94
`+
We use an exponentially weighted moving average, imitating the
`
``
95
`+
load calculation on Unix systems.
`
``
96
`+
https://en.wikipedia.org/wiki/Load_(computing)#Unix-style_load_calculation
`
``
97
`+
new_load = self.load * LOAD_FACTOR_1 + load * (1.0 - LOAD_FACTOR_1)
`
``
98
`+
self.load = new_load
`
``
99
+
``
100
`+
return self.load
`