consolekit thread explosion ...

[Dan Nicholson]

On Mon, Jun 29, 2009 at 4:30 PM, Kay Sievers<kay.sievers at vrfy.org> wrote:
> On Wed, May 14, 2008 at 23:04, William Jon McCann<mccann at jhu.edu> wrote:
>> On Wed, May 14, 2008 at 10:55 AM, Michael Meeks
>> <michael.meeks at novell.com> wrote:
>>> Hi there,
>>>
>>>        Kay mentioned you might be interested in this :-)
>>>
>>>        Having logged into & out of my (opensuse factory) desktop for a while -
>>> I run 'pstree -p' and I'm always amazed at how much thread-space
>>> consolekit takes up in that view.
>>>
>>> $ pstree -p | grep console-kit | wc -l
>>> 62
>>>
>>>        Do we really need 62 threads they all appear quiescent; and
>>> interestingly lsof shows:
>> ...
>>>        over and over again: is that deliberate ? one file handle per thread ?
>>> I guess I don't know what that is doing; presumably it's a known issue
>>> (?) - if not, should I file it as a bug ? I have:
>>
>> That is deliberate.  The way it works, for now, is each of those
>> threads are blocking in VT_WAITACTIVE.  Last I checked, the signals
>> from VT_GETSTATE are only delivered to one process, in most cases:
>> Xorg.  And signals are yuck anyway.
>>
>> So, looking forward, two possible paths are: fix the VT subsystem,
>> don't use the VT subsystem.  Maybe the later is a more viable option
>> these days...
>
> I like old mails. :)
>
> Lennart and I looked into this a few days ago, and it seems there is a
> pretty trivial fix to the kernel possible, to live with only one
> thread in CK.
>
> Or maybe we just limit the VCs to 4 or 8 instead of 64, which should
> cover more than needed, right?

I recall seeing a thread on lkml a couple years ago where someone
proposed a patch to reduce the number of virtual consoles at build
time, but it didn't go over well because the 64 is part of an API. I
can't recall the details, but just a heads up that there may be push
back if you try to go that route. I personally would love to see a way
to limit VCs, though, since I can't think of any way you could use 64
VTs.

--
Dan