get a process by name and get a processes' descendants

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Here is a diff for two new additions to psutil.
One is psutil.proc_by_name, which g.rodola actually wrote in issue 241. I just 
included it here in the diff, and changed it from returning an iterator to a 
list.

The other is a get_lowest_descendants method on the Process object, which 
fetches all descendants from a process, that don't have child processes 
themselves.

The use case that I have for this method is that I want to see what I am 
currently doing in my terminal application. So my terminal will have a couple 
of bash child processes (one for each tab), and each of those has child 
processes as well, some being an ssh command into another machine, some being a 
python interpreter in a certain folder, or a vi instance on a certain file, etc.

With the get_lowest_descendants method I can easily fetch those descendants and 
what they are doing.

Original issue reported on code.google.com by dolfandr...@gmail.com on 19 Jan 2012 at 10:39

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and now with the diff attached :)

Original comment by dolfandr...@gmail.com on 19 Jan 2012 at 10:39

Attachments:

• init.py.diff

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> patch in attachment adds a get_lowest_descendants()
> method on the Process object, which fetches all 
> descendants from a process, that don't have 
> child processes themselves.

Mmm interesting.
I think I don't have a clear mind about this yet.
At first it seems kind of useful, on the other hand I'm not sure about its 
reliability.
Imagine this:

process A creates process B which creates process C

In normal circumstances your method would return A, B and C, but if B gets 
terminated in meantime you're gonna lose the reference to C and get only A in 
return.

Other than that, I think this would be better served by adding an extra 
argument to get_children() method:

>>> get_children(recursive=True)

...and make it return only B and C but not itself (A).

Also, it seems natural to make get_children() return an iterator rather than a 
list.
The same should be done for get_open_files(), get_connections() and 
get_threads() (I'll file a new ticket for that).

Jay, what do you think?

Original comment by g.rodola on 19 Jan 2012 at 1:33

• Changed state: WaitingForReview

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In your example where process A creates process B which creates process C, 
the code would only return process C, not B, since B has children.

Another option for my use case would then be 
>>> filter(lambda x: len(x.children)==0,get_children(recursive=True))

Original comment by dolfandr...@gmail.com on 19 Jan 2012 at 2:07

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This is now implemented in r1282.
Please look at the docstring and let me know if with this you're able to cover 
your use case.

Original comment by g.rodola on 7 Apr 2012 at 3:38

• Changed state: Started

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Change recursion algorithm as r1283.

Original comment by g.rodola on 8 Apr 2012 at 12:37

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Original comment by g.rodola on 12 Apr 2012 at 6:15

• Changed state: FixedInSVN
• Added labels: Milestone-0.5.0, Usability

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0.5.0 is finally out. Closing out as fixed.

Original comment by g.rodola on 27 Jun 2012 at 6:54

• Changed state: Fixed

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[deleted comment]

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Updated csets after the SVN -> Mercurial migration:
r1282 == revision 19893ece7eff
r1283 == revision 0e9fabea61e2

Original comment by g.rodola on 2 Mar 2013 at 12:06