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Windows services support

Giampaolo RodolaMay 15, 20162 min readnew-apireleasewindows

New psutil 4.2.0 is out. The highlight of this release is the support for Windows services (executables that run at system startup, similar to UNIX init scripts):

>>> import psutil
>>> list(psutil.win_service_iter())
[<WindowsService(name='AeLookupSvc', display_name='Application Experience') at 38850096>,
 <WindowsService(name='ALG', display_name='Application Layer Gateway Service') at 38850128>,
 <WindowsService(name='APNMCP', display_name='Ask Update Service') at 38850160>,
 <WindowsService(name='AppIDSvc', display_name='Application Identity') at 38850192>,
 ...]
>>> s = psutil.win_service_get('alg')
>>> s.as_dict()
{'binpath': 'C:\\Windows\\System32\\alg.exe',
 'description': 'Provides support for 3rd party protocol plug-ins for Internet Connection Sharing',
 'display_name': 'Application Layer Gateway Service',
 'name': 'alg',
 'pid': None,
 'start_type': 'manual',
 'status': 'stopped',
 'username': 'NT AUTHORITY\\LocalService'}

I decided to do this mainly because I find pywin32 APIs too low levelish. Having something like this in psutil can be useful to discover and monitor services more easily. The code was implemented in PR-803. The API for querying a service is similar to psutil.Process. You can get a reference to a service object by using its name (which is unique for every service) and then use methods like WindowsService.name() and WindowsService.status():

>>> s = psutil.win_service_get('alg')
>>> s.name()
'alg'
>>> s.status()
'stopped'

Initially I thought about providing a full set of APIs to handle all aspects of service management, including start(), stop(), restart(), install(), uninstall() and modify(). However, I soon realized I would have ended up reimplementing what pywin32 already provides, at the cost of overcrowding the psutil API (see my reasoning here). I think psutil really focuses on monitoring, not on installing and modifying system components, especially something as critical as a Windows service.

Considerations about Windows services

Typically, a Windows service is an executable (.exe) that runs at system startup and continues running in the background. It is roughly the equivalent of a UNIX init script. All services are controlled by a “manager”, which keeps track of their status and metadata (e.g. description, startup type). It is interesting to note that since (most) services are bound to an executable (and hence a process) you can reference them via their process PID:

>>> s = psutil.win_service_get('sshd')
>>> s
<WindowsService(name='sshd', display_name='Open SSH server') at 38853046>
>>> s.pid()
1865
>>> p = psutil.Process(1865)
>>> p
<psutil.Process(pid=19547, name='sshd.exe') at 140461487781328>
>>> p.exe()
'C:\CygWin\bin\sshd'

Other improvements

psutil 4.2.0 comes with 2 other enhancements for Linux:

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