psutil It's a very powerful third-party library , Simple to use , Here is mainly to sort out .
First look at the official statement ：
psutil (python system and process utilities) is a cross-platform library for retrieving information on running processes and system utilization (CPU, memory, disks, network, sensors) in Python.
It is useful mainly for system monitoring, profiling, limiting process resources and the management of running processes.
It implements many functionalities offered by UNIX command line tools such as: ps, top, lsof, netstat, ifconfig, who, df, kill, free, nice, ionice, iostat, iotop, uptime, pidof, tty, taskset, pmap.
psutil It's a cross platform library , You can obtain the system hardware utilization （ Include CPU, memory, disks, network, sensors） And the running process . It is mainly used for system resource monitoring and process management .
install psutil：
# pip3 install psutil
>>> import psutil
>>> dir(psutil)
['AF_LINK', 'AIX', 'AccessDenied', 'BSD', 'CONN_CLOSE', 'CONN_CLOSE_WAIT', 'CONN_CLOSING', 'CONN_ESTABLISHED', 'CONN_FIN_WAIT1', 'CONN_FIN_WAIT2', 'CONN_LAST_ACK', 'CONN_LISTEN', 'CONN_NONE', 'CONN_SYN_RECV', 'CONN_SYN_SENT', 'CONN_TIME_WAIT', 'Error', 'FREEBSD', 'IOPRIO_CLASS_BE', 'IOPRIO_CLASS_IDLE', 'IOPRIO_CLASS_NONE', 'IOPRIO_CLASS_RT', 'LINUX', 'NETBSD', 'NIC_DUPLEX_FULL', 'NIC_DUPLEX_HALF', 'NIC_DUPLEX_UNKNOWN', 'NoSuchProcess', 'OPENBSD', 'OSX', 'POSIX', 'POWER_TIME_UNKNOWN', 'POWER_TIME_UNLIMITED', 'PROCFS_PATH', 'Popen', 'Process', 'RLIMIT_AS', 'RLIMIT_CORE', 'RLIMIT_CPU', 'RLIMIT_DATA', 'RLIMIT_FSIZE', 'RLIMIT_LOCKS', 'RLIMIT_MEMLOCK', 'RLIMIT_MSGQUEUE', 'RLIMIT_NICE', 'RLIMIT_NOFILE', 'RLIMIT_NPROC', 'RLIMIT_RSS', 'RLIMIT_RTPRIO', 'RLIMIT_RTTIME', 'RLIMIT_SIGPENDING', 'RLIMIT_STACK', 'RLIM_INFINITY', 'STATUS_DEAD', 'STATUS_DISK_SLEEP', 'STATUS_IDLE', 'STATUS_LOCKED', 'STATUS_RUNNING', 'STATUS_SLEEPING', 'STATUS_STOPPED', 'STATUS_TRACING_STOP', 'STATUS_WAITING', 'STATUS_WAKING', 'STATUS_ZOMBIE', 'SUNOS', 'TimeoutExpired', 'WINDOWS', 'ZombieProcess', '_PY3', '_TOTAL_PHYMEM', '__all__', '__author__', '__builtins__', '__cached__', '__doc__', '__file__', '__loader__', '__name__', '__package__', '__path__', '__spec__', '__version__', '_as_dict_attrnames', '_assert_pid_not_reused', '_common', '_compat', '_cpu_busy_time', '_cpu_tot_time', '_last_cpu_times', '_last_cpu_times_2', '_last_per_cpu_times', '_last_per_cpu_times_2', '_pmap', '_pslinux', '_psplatform', '_psposix', '_psutil_linux', '_psutil_posix', '_timer', '_wrap_numbers', 'boot_time', 'callable', 'collections', 'contextlib', 'cpu_count', 'cpu_percent', 'cpu_stats', 'cpu_times', 'cpu_times_percent', 'disk_io_counters', 'disk_partitions', 'disk_usage', 'errno', 'functools', 'long', 'net_connections', 'net_if_addrs', 'net_if_stats', 'net_io_counters', 'os', 'pid_exists', 'pids', 'process_iter', 'pwd', 'sensors_battery', 'sensors_fans', 'sensors_temperatures', 'signal', 'subprocess', 'swap_memory', 'sys', 'test', 'time', 'traceback', 'users', 'version_info', 'virtual_memory', 'wait_procs']
Usage is as follows ：
CPU
psutil.cpu_times(percpu=False)
psutil.cpu_percent(interval=None, percpu=False)
psutil.cpu_times_percent(interval=None, percpu=False)
psutil.cpu_stats()
psutil.cpu_freq(percpu=False)
psutil.cpu_count(logical=True)： obtain CPU Number or core number .
Return the number of logical CPUs in the system (same as os.cpu_count() in Python 3.4) or None if undetermined.
This number may not be equivalent to the number of CPUs the current process can actually use in case process CPU affinity has been changed or Linux cgroups are being used.
The number of usable CPUs can be obtained with len(psutil.Process().cpu_affinity()).
If logical is False return the number of physical cores only
Memory
psutil.virtual_memory()： Get memory usage information .
psutil.swap_memory()： Get the usage information of swap memory .
Disk
psutil.disk_partitions(all=False)： Get hard disk partition information .
psutil.disk_usage(path)： Get hard disk usage information .
psutil.disk_io_counters(perdisk=False, nowrap=True)： Get disk IO Information .
Network
psutil.net_io_counters(pernic=False)： Get network IO Information .
psutil.net_connections(kind='inet')： obtain socket Connection information .
psutil.net_if_addrs()： Get various address information of each network card （ Include IP Address 、 network address 、 Broadcast address, etc ）.
psutil.net_if_stats()： Get the hardware information of the network card （ Including whether to enable 、 Simplex or duplex 、speed、MTU）.
Sensor
psutil.sensors_temperatures(fahrenheit=False)： Get the temperature of the hardware （ Include CPU、 Hard disk, etc. ）.
psutil.sensors_fans()： Get the speed of the fan .
psutil.sensors_battery()： Get battery status information .
Other system information
psutil.boot_time()： Get the start time of the system , Note that it is not the starting time , Is the timestamp at startup .
psutil.users()： Get the user currently logged in to the system .
Process, Get process information
psutil.pids()： Get all the currently running PID. What is returned is a list of process numbers .
psutil.pid_exists(pid)： Detect the specified pid Whether there is .
psutil.wait_procs(procs, timeout=None, callback=None)： Wait for the process to finish .
psutil.process_iter(attrs=None, ad_value=None)： Return to a generator , Iteratively get the attribute information of all processes , It can be used attrs Specify the properties to display , And then call Process.as_dict() Method to get the relevant properties .
>>> psutil.process_iter()
<generator object process_iter at 0x7f5321d8e468>
>>> p = psutil.process_iter()
>>> for i in p:
... print(i)
...
psutil.Process(pid=1, name='systemd')
psutil.Process(pid=2, name='kthreadd')
psutil.Process(pid=3, name='ksoftirqd/0')
psutil.Process(pid=5, name='kworker/0:0H')
... ...
psutil.Process(pid=32284, name='bioset')
psutil.Process(pid=32285, name='dm-thin')
psutil.Process(pid=32286, name='bioset')
Process class
class psutil.Process(pid=None)：Process class .
Represents an OS process with the given pid. If pid is omitted current process pid (os.getpid()) is used. Raise NoSuchProcess if pid does not exist.
pid：The process PID. This is the only (read-only) attribute of the class.
ppid()：The process parent PID.
name()：The process name.
exe()：The process executable as an absolute path.
cmdline()：The command line this process has been called with as a list of strings. The return value is not cached because the cmdline of a process may change.
environ()：The environment variables of the process as a dict. Note: this might not reflect changes made after the process started.
create_time()：The process creation time as a floating point number expressed in seconds since the epoch, in UTC. The return value is cached after first call.
parent()：Utility method which returns the parent process as a Process object preemptively checking whether PID has been reused. If no parent PID is known return None.
status()：The current process status as a string.
cwd()：The process current working directory as an absolute path.
username()：The name of the user that owns the process. On UNIX this is calculated by using real process uid.
uids()：The real, effective and saved user ids of this process as a named tuple.
gids()：The real, effective and saved group ids of this process as a named tuple.
terminal()：The terminal associated with this process, if any, else None.
io_counters()：Return process I/O statistics as a named tuple.
num_fds()：The number of file descriptors currently opened by this process (non cumulative).
num_handles()：The number of handles currently used by this process (non cumulative).
num_threads()：The number of threads currently used by this process (non cumulative).
threads()：Return threads opened by process as a list of named tuples including thread id and thread CPU times (user/system).
cpu_times()：Return a (user, system, children_user, children_system) named tuple representing the accumulated process time, in seconds.
cpu_percent(interval=None)：Return a float representing the process CPU utilization as a percentage which can also be > 100.0 in case of a process running multiple threads on different CPUs.
cpu_affinity(cpus=None)：Get or set process current CPU affinity. CPU affinity consists in telling the OS to run a process on a limited set of CPUs only. If no argument is passed it returns the current CPU affinity as a list of integers. If passed it must be a list of integers specifying the new CPUs affinity. If an empty list is passed all eligible CPUs are assumed (and set).
cpu_num()：Return what CPU this process is currently running on.
memory_info()：Return a named tuple with variable fields depending on the platform representing memory information about the process.
memory_percent(memtype="rss")：Compare process memory to total physical system memory and calculate process memory utilization as a percentage. memtype argument is a string that dictates what type of process memory you want to compare against. You can choose between the named tuple field names returned by memory_info() and memory_full_info() (defaults to "rss").
children(recursive=False)：Return the children of this process as a list of Process objects, preemptively checking whether PID has been reused. If recursive is True return all the parent descendants.
open_files()：Return regular files opened by process as a list of named tuples.
connections(kind="inet")：Return socket connections opened by process as a list of named tuples.
is_running()：Return whether the current process is running in the current process list.
send_signal(signal)：Send a signal to process preemptively checking whether PID has been reused.
suspend()：Suspend process execution with SIGSTOP signal preemptively checking whether PID has been reused.
resume()：Resume process execution with SIGCONT signal preemptively checking whether PID has been reused.
terminate()：Terminate the process with SIGTERM signal preemptively checking whether PID has been reused.
kill()：Kill the current process by using SIGKILL signal preemptively checking whether PID has been reused.
wait(timeout=None)：Wait for process termination and if the process is a children of the current one also return the exit code, else None. To wait for multiple processes use psutil.wait_procs().
Popen class
class psutil.Popen(*args, **kwargs)：Popen class .
A more convenient interface to stdlib subprocess.Popen. It starts a sub process and you deal with it exactly as when using subprocess.Popen but in addition it also provides all the methods of psutil.Process class.
It's a ratio. subprocess.Popen A more convenient interface to the standard library . It starts a child process , Usage and subprocess.Popen Exactly the same , But it provides all psutil.Process Class , So its use method is in addition to the methods listed above , Also need reference subprocess.Popen Supported methods . The difference is , It will check in advance PID Whether it is reused , Will not accidentally kill other processes .
>>> import psutil
>>> from subprocess import PIPE
>>> p = psutil.Popen(["/usr/bin/python", "-c", "print('hello')"], stdout=PIPE)
>>>
>>> p.name()
'python'
>>> p.username()
'root'
>>> p.communicate()
(b'hello\n', None)
>>> p.wait()
0
What needs to be summarized is ,subprocess and psutil.Popen It is often used to call external commands , That is to execute system commands , Text communication between processes can only be carried out through pipelines , From the above example PIPE Can be seen , Here you can read subprocess Official documents of .
in addition , The interfaces commonly used to call system commands are os.system() and os.popen(), But the design and use are simpler .
