resource
fcntl — fcntl and ioctl 系统调用
fcntl
ioctl
此模块提供度量和控制程序利用系统资源的基本机制。
可用性 ：Unix，非 Emscripten，非 WASI。
符号常量用于指定特定系统资源，并请求有关当前进程或其子级的使用信息。
An OSError 被引发当 syscall 故障时。
OSError
被弃用别名化的 OSError .
3.3 版改变： 遵循 PEP 3151 ，此类是别名化的 OSError .
可以限制资源的使用，使用 setrlimit() function described below. Each resource is controlled by a pair of limits: a soft limit and a hard limit. The soft limit is the current limit, and may be lowered or raised by a process over time. The soft limit can never exceed the hard limit. The hard limit can be lowered to any value greater than the soft limit, but not raised. (Only processes with the effective UID of the super-user can raise a hard limit.)
setrlimit()
The specific resources that can be limited are system dependent. They are described in the getrlimit(2) man page. The resources listed below are supported when the underlying operating system supports them; resources which cannot be checked or controlled by the operating system are not defined in this module for those platforms.
Constant used to represent the limit for an unlimited resource.
返回元组 (soft, hard) with the current soft and hard limits of resource 。引发 ValueError if an invalid resource is specified, or error if the underlying system call fails unexpectedly.
(soft, hard)
ValueError
error
Sets new limits of consumption of resource 。 limits argument must be a tuple (soft, hard) of two integers describing the new limits. A value of RLIM_INFINITY can be used to request a limit that is unlimited.
RLIM_INFINITY
引发 ValueError if an invalid resource is specified, if the new soft limit exceeds the hard limit, or if a process tries to raise its hard limit. Specifying a limit of RLIM_INFINITY when the hard or system limit for that resource is not unlimited will result in a ValueError . A process with the effective UID of super-user can request any valid limit value, including unlimited, but ValueError will still be raised if the requested limit exceeds the system imposed limit.
setrlimit 还可能引发 error 若底层系统调用失败。
setrlimit
VxWorks 仅支持设置 RLIMIT_NOFILE .
RLIMIT_NOFILE
引发 审计事件 resource.setrlimit 采用自变量 resource , limits .
resource.setrlimit
limits
组合 setrlimit() and getrlimit() in one function and supports to get and set the resources limits of an arbitrary process. If pid is 0, then the call applies to the current process. resource and limits 拥有相同含义如在 setrlimit() ，除了 limits is optional.
getrlimit()
当 limits is not given the function returns the resource limit of the process pid 。当 limits is given the resource limit of the process is set and the former resource limit is returned.
引发 ProcessLookupError 当 pid can’t be found and PermissionError when the user doesn’t have CAP_SYS_RESOURCE for the process.
ProcessLookupError
PermissionError
CAP_SYS_RESOURCE
引发 审计事件 resource.prlimit 采用自变量 pid , resource , limits .
resource.prlimit
pid
可用性 : Linux >= 2.6.36 with glibc >= 2.13.
Added in version 3.4.
These symbols define resources whose consumption can be controlled using the setrlimit() and getrlimit() functions described below. The values of these symbols are exactly the constants used by C programs.
The Unix man page for getrlimit(2) lists the available resources. Note that not all systems use the same symbol or same value to denote the same resource. This module does not attempt to mask platform differences — symbols not defined for a platform will not be available from this module on that platform.
The maximum size (in bytes) of a core file that the current process can create. This may result in the creation of a partial core file if a larger core would be required to contain the entire process image.
The maximum amount of processor time (in seconds) that a process can use. If this limit is exceeded, a SIGXCPU signal is sent to the process. (See the signal module documentation for information about how to catch this signal and do something useful, e.g. flush open files to disk.)
SIGXCPU
signal
The maximum size of a file which the process may create.
The maximum size (in bytes) of the process’s heap.
The maximum size (in bytes) of the call stack for the current process. This only affects the stack of the main thread in a multi-threaded process.
The maximum resident set size that should be made available to the process.
The maximum number of processes the current process may create.
The maximum number of open file descriptors for the current process.
The BSD name for RLIMIT_NOFILE .
The maximum address space which may be locked in memory.
The largest area of mapped memory which the process may occupy.
可用性 : FreeBSD >= 11.
The maximum area (in bytes) of address space which may be taken by the process.
The number of bytes that can be allocated for POSIX message queues.
可用性 : Linux >= 2.6.8.
The ceiling for the process’s nice level (calculated as 20 - rlim_cur).
可用性 : Linux >= 2.6.12.
The ceiling of the real-time priority.
The time limit (in microseconds) on CPU time that a process can spend under real-time scheduling without making a blocking syscall.
可用性 : Linux >= 2.6.25.
The number of signals which the process may queue.
The maximum size (in bytes) of socket buffer usage for this user. This limits the amount of network memory, and hence the amount of mbufs, that this user may hold at any time.
可用性 : FreeBSD.
The maximum size (in bytes) of the swap space that may be reserved or used by all of this user id’s processes. This limit is enforced only if bit 1 of the vm.overcommit sysctl is set. Please see tuning(7) for a complete description of this sysctl.
The maximum number of pseudo-terminals created by this user id.
The maximum number of kqueues this user id is allowed to create.
Added in version 3.10.
这些函数用于检索资源使用信息：
This function returns an object that describes the resources consumed by either the current process or its children, as specified by the who parameter. The who parameter should be specified using one of the RUSAGE_* constants described below.
RUSAGE_*
简单范例：
from resource import * import time # a non CPU-bound task time.sleep(3) print(getrusage(RUSAGE_SELF)) # a CPU-bound task for i in range(10 ** 8): _ = 1 + 1 print(getrusage(RUSAGE_SELF))
The fields of the return value each describe how a particular system resource has been used, e.g. amount of time spent running is user mode or number of times the process was swapped out of main memory. Some values are dependent on the clock tick internal, e.g. the amount of memory the process is using.
For backward compatibility, the return value is also accessible as a tuple of 16 elements.
The fields ru_utime and ru_stime of the return value are floating point values representing the amount of time spent executing in user mode and the amount of time spent executing in system mode, respectively. The remaining values are integers. Consult the getrusage(2) man page for detailed information about these values. A brief summary is presented here:
ru_utime
ru_stime
索引
字段
资源
0
1
2
ru_maxrss
3
ru_ixrss
4
ru_idrss
5
ru_isrss
6
ru_minflt
7
ru_majflt
8
ru_nswap
9
ru_inblock
10
ru_oublock
11
ru_msgsnd
12
ru_msgrcv
13
ru_nsignals
14
ru_nvcsw
15
ru_nivcsw
此函数会引发 ValueError if an invalid who parameter is specified. It may also raise error exception in unusual circumstances.
Returns the number of bytes in a system page. (This need not be the same as the hardware page size.)
下列 RUSAGE_* symbols are passed to the getrusage() function to specify which processes information should be provided for.
getrusage()
Pass to getrusage() to request resources consumed by the calling process, which is the sum of resources used by all threads in the process.
Pass to getrusage() to request resources consumed by child processes of the calling process which have been terminated and waited for.
Pass to getrusage() to request resources consumed by both the current process and child processes. May not be available on all systems.
Pass to getrusage() to request resources consumed by the current thread. May not be available on all systems.
Added in version 3.2.
syslog — Unix syslog 库例程
syslog
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