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https://github.com/tangerineturtle1/NX2navi.git
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53 lines
2.5 KiB
Python
53 lines
2.5 KiB
Python
"""Memory the machine can still give to new processes, for sizing worker pools (stdlib only, Windows)."""
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import ctypes
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import ctypes.wintypes as wt
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import sys
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JOB_OBJECT_EXTENDED_LIMIT_INFORMATION = 9
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LIMIT_PROCESS_MEMORY = 0x100
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LIMIT_JOB_MEMORY = 0x200
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class _MemStatus(ctypes.Structure):
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_fields_ = [('dwLength', wt.DWORD), ('dwMemoryLoad', wt.DWORD)] + \
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[(n, ctypes.c_ulonglong) for n in ('total', 'avail', 'tpf', 'apf', 'tv', 'av', 'aev')]
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class _JobLimits(ctypes.Structure):
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_fields_ = [('PerProcessUserTimeLimit', ctypes.c_longlong), ('PerJobUserTimeLimit', ctypes.c_longlong),
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('LimitFlags', wt.DWORD), ('MinimumWorkingSetSize', ctypes.c_size_t),
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('MaximumWorkingSetSize', ctypes.c_size_t), ('ActiveProcessLimit', wt.DWORD),
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('Affinity', ctypes.c_size_t), ('PriorityClass', wt.DWORD), ('SchedulingClass', wt.DWORD),
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('r_ops', ctypes.c_ulonglong), ('w_ops', ctypes.c_ulonglong), ('o_ops', ctypes.c_ulonglong),
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('r_bytes', ctypes.c_ulonglong), ('w_bytes', ctypes.c_ulonglong), ('o_bytes', ctypes.c_ulonglong),
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('ProcessMemoryLimit', ctypes.c_size_t), ('JobMemoryLimit', ctypes.c_size_t),
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('PeakProcessMemoryUsed', ctypes.c_size_t), ('PeakJobMemoryUsed', ctypes.c_size_t)]
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def _job_headroom():
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"""Bytes left under the memory limit of the job object this process runs in, or None without such a limit."""
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k32 = ctypes.WinDLL('kernel32', use_last_error=True)
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k32.QueryInformationJobObject.argtypes = [wt.HANDLE, ctypes.c_int, ctypes.c_void_p, wt.DWORD, ctypes.c_void_p]
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info = _JobLimits()
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# A null handle asks about the job of the calling process.
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if not k32.QueryInformationJobObject(None, JOB_OBJECT_EXTENDED_LIMIT_INFORMATION, ctypes.byref(info),
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ctypes.sizeof(info), None):
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return None
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if info.LimitFlags & LIMIT_JOB_MEMORY:
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return max(0, info.JobMemoryLimit - info.PeakJobMemoryUsed)
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if info.LimitFlags & LIMIT_PROCESS_MEMORY:
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return info.ProcessMemoryLimit
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return None
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def available_ram():
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"""Physical memory not in use right now, capped by the job memory limit if there is one. None off Windows."""
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if sys.platform != 'win32':
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return None
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status = _MemStatus()
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status.dwLength = ctypes.sizeof(status)
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if not ctypes.windll.kernel32.GlobalMemoryStatusEx(ctypes.byref(status)):
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return None
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headroom = _job_headroom()
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return status.avail if headroom is None else min(status.avail, headroom)
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