Question

我写的代码已经在Windows XP和Windows Server 2008 64位上运行。但是，我刚刚启动了一个亚马逊Windows 64位实例，但代码失败了。

非常简单，看起来像这样

import multiprocessing

processors = multiprocessing.cpu_count()
print processors

我收到一个NotImplementedError，我不明白，而且文档对解释没有帮助。

我只是不明白为什么它可以在一台服务器上运行，而不是在另一台服务器上运行相同的Python 2.7

其他人遇到此问题/错误？

Answer 1

它可能只是多处理模块，尝试使用它可能有效的psutil模块。在你的情况下只做：

import psutil
processors = psutil.cpu_count()
print processors
>>> 4

我在亚马逊Windows 64位上试过这个并且效果很好。

Answer 2

如果您需要使用psutil获取CPU数量，则可以改为使用ctypes：

import ctypes
from ctypes import wintypes

class SYSTEM_INFO(ctypes.Structure):
    _fields_ = [
        ('wProcessorArchitecture', wintypes.WORD),
        ('wReserved', wintypes.WORD),
        ('dwPageSize', wintypes.DWORD),
        ('lpMinimumApplicationAddress', wintypes.LPVOID),
        ('lpMaximumApplicationAddress', wintypes.LPVOID),
        ('dwActiveProcessorMask', ctypes.c_size_t),
        ('dwNumberOfProcessors', wintypes.DWORD),
        ('dwProcessorType', wintypes.DWORD),
        ('dwAllocationGranularity', wintypes.DWORD),
        ('wProcessorLevel', wintypes.WORD),
        ('wProcessorRevision', wintypes.WORD),
    ]

GetSystemInfo = ctypes.windll.kernel32.GetSystemInfo
GetSystemInfo.restype = None
GetSystemInfo.argtypes = [ctypes.POINTER(SYSTEM_INFO)]

def cpu_count():
    sysinfo = SYSTEM_INFO()
    GetSystemInfo(sysinfo)
    num = sysinfo.dwNumberOfProcessors
    if num == 0:
        raise NotImplementedError('cannot determine number of cpus')
    return num

修改：

这是try的替代方法，它可能返回与NUMBER_OF_PROCESSORS环境变量相同的值。请注意，文档说使用GetSystemInfo代替，这是psutil使用的。这也是使用本机NT API，通常不鼓励。

import ctypes from ctypes import wintypes SystemBasicInformation = 0 class SYSTEM_INFORMATION(ctypes.Structure): pass PSYSTEM_INFORMATION = ctypes.POINTER(SYSTEM_INFORMATION) class SYSTEM_BASIC_INFORMATION(SYSTEM_INFORMATION): _fields_ = [ ('Reserved1', wintypes.BYTE * 24), ('Reserved2', wintypes.LPVOID * 4), ('NumberOfProcessors', ctypes.c_ubyte), ] ntdll = ctypes.windll.ntdll NtQuerySystemInformation = ntdll.NtQuerySystemInformation NtQuerySystemInformation.argtypes = [ wintypes.LONG, # SystemInformationClass PSYSTEM_INFORMATION, # SystemInformation wintypes.ULONG, # SystemInformationLength wintypes.PULONG] # ReturnLength def cpu_count(): info = SYSTEM_BASIC_INFORMATION() retlen = wintypes.ULONG() status = NtQuerySystemInformation(SystemBasicInformation, info, ctypes.sizeof(info), retlen) num = info.NumberOfProcessors if status < 0 or num == 0: raise NotImplementedError('cannot determine number of cpus') return num

Answer 3

失败是由于multiprocessing.cpu_count（）依赖于Windows上的NUMBER_OF_PROCESSORS环境变量，偶尔会丢失。使用wmi作为替代品。感谢您提出建议eryksun。

if sys.platform == 'win32':
    import wmi
    c = wmi.WMI(find_classes=False)
    return sum(x.NumberOfLogicalProcessors for x in c.Win32_Processor())
else:
    return multiprocessing.cpu_count()

Python CPU Count在一台Windows服务器上运行但在另一台服务器上运行？

3 个答案: