os.getpriority() and os.setpriority()

[giampaolo]

BPO	10784
Nosy	@loewis, @birkenfeld, @orsenthil, @pitrou, @giampaolo, @tiran
Files	getsetpriority.patch

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

Show more details

GitHub fields:

assignee = 'https://github.com/giampaolo'
closed_at = <Date 2011-02-26.06:40:26.507>
created_at = <Date 2010-12-28.01:46:49.093>
labels = ['extension-modules', 'type-feature']
title = 'os.getpriority() and os.setpriority()'
updated_at = <Date 2011-02-26.06:40:26.506>
user = 'https://github.com/giampaolo'

bugs.python.org fields:

activity = <Date 2011-02-26.06:40:26.506>
actor = 'pitrou'
assignee = 'giampaolo.rodola'
closed = True
closed_date = <Date 2011-02-26.06:40:26.507>
closer = 'pitrou'
components = ['Extension Modules']
creation = <Date 2010-12-28.01:46:49.093>
creator = 'giampaolo.rodola'
dependencies = []
files = ['20177']
hgrepos = []
issue_num = 10784
keywords = ['patch']
message_count = 12.0
messages = ['124751', '124752', '124763', '124778', '124780', '125887', '125908', '129426', '129427', '129474', '129501', '129504']
nosy_count = 7.0
nosy_names = ['loewis', 'georg.brandl', 'orsenthil', 'pitrou', 'giampaolo.rodola', 'christian.heimes', 'rosslagerwall']
pr_nums = []
priority = 'normal'
resolution = 'fixed'
stage = 'patch review'
status = 'closed'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue10784'
versions = ['Python 3.3']

[giampaolo]

After having implemented a similar thing in psutil ( http://code.google.com/p/psutil/issues/detail?id=142 ) I decided to contribute a patch for Python which exposes getpriority() and setpriority() POSIX calls in the os module.

They can be used to get/set process niceness/priority in a fashion similar to os.nice() but extended to *all* processes instead of just os.getpid():
http://linux.die.net/man/2/setpriority

[giampaolo]

Forgot to attach the patch.

[rosslagerwall]

Patch looks good, just one thing:

In setpriority(), it should be possible to use the Py_RETURN_NONE; macro instead of INCREFing manually.

[birkenfeld]

Looks good. Would there be a point in making any of the parameters optional?

[loewis]

Looks good. Would there be a point in making any of the parameters optional?

No. The API should look exactly as it does on the system level. Anybody
calling these functions should know how call them.

[giampaolo]

Question: should Py_BEGIN/END_ALLOW_THREADS be used around getpriority() and setpriority() calls? It's still not clear to me when to use them exactly.

[loewis]

You should use begin/end allow threads when the system call might block. To get an indication, trace through the kernel code of some system; my guess is that these are typically non-blocking (i.e. return immediately) - but I might be wrong.

[giampaolo]

Committed in r88608 including Py_RETURN_NONE and Py_BEGIN/END_ALLOW_THREADS changes.

[giampaolo]

Misc/NEWS updated in r88609.

[pitrou]

======================================================================
ERROR: test_set_get_priority (test.test_os.ProgramPriorityTests)
----------------------------------------------------------------------

Traceback (most recent call last):
  File "/home/buildbot/buildarea/3.x.ochtman-gentoo-amd64/build/Lib/test/test_os.py", line 1283, in test_set_get_priority
    os.setpriority(os.PRIO_PROCESS, os.getpid(), base)
OSError: [Errno 13] Permission denied

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/buildbot/buildarea/3.x.ochtman-gentoo-amd64/build/Lib/test/test_os.py", line 1285, in test_set_get_priority
    if err.errno != errno.EACCESS:
AttributeError: 'module' object has no attribute 'EACCESS'

[orsenthil]

On Sat, Feb 26, 2011 at 12:11:10AM +0000, Antoine Pitrou wrote:

if err.errno != errno.EACCESS:

AttributeError: 'module' object has no attribute 'EACCESS'

That was one 'S' too many. Should be errno.EACCES
Looks like Antoine has fixed it in r88627.

[pitrou]

Indeed.