Headless snapshotting (was: Re: [squeak-dev] binary development (was: 3.11 and the trunk))

Eliot Miranda eliot.miranda at gmail.com
Wed Aug 26 18:13:40 UTC 2009


On Wed, Aug 26, 2009 at 10:58 AM, David Farber <dfarber at numenor.com> wrote:

>
> On Aug 26, 2009, at 9:53 AM, Eliot Miranda wrote:
>
> On Tue, Aug 25, 2009 at 3:54 PM, David Farber <dfarber at numenor.com> wrote:
>
>>
>> On Aug 25, 2009, at 2:28 PM, Eliot Miranda wrote:
>>
>>  One of the things the headless support in VW allows which is quite nice
>>> is taking a shapshot which can then be restarted in a headless mode for
>>> debugging.
>>>
>>
>> Eliot - Was this VM or image-side support?  Can you describe how it
>> worked?
>
>
> All image side; no VM support.  I can't describe it in detail as I never
> worked on it.  But the basic idea is to have a switchable headless system in
> the image so that in deployment it runs headless and when an error occurs
> the error handler temporarily throws the switch, saves a snapshot and resets
> the switch.  When the snapshot is restarted it will come up headful because
> the switch was thrown before the snapshot was taken.  In the resuming
> snapshot the error handler then does something like an on: .. do: [:ex| self
> shapshotHeadful. ex pass] to allow the GUI to display the debugger.
>
>
> I was hoping you were going to say VM side.  :)  Or, rather, I was hoping
> that the context of your original message was initiating a snapshot from
> outside a image (i.e. in response to a nightly cron job to backup the image
> or a system shutdown event).
>
> But, back to headless/headfull for a moment, doesn't Squeak do this
> automatically already?  When I run an image in headless mode, all that
> happens is that no OS window is opened--but the Squeak UI objects are all
> there (and running) in the image.
>

Right.


>  Does VW do something more, like destroy all the UI objects?
>

No.  Its just a switch and routes to either the GUI or e.g. standard i/o.




>
>>> Not quite the same, but very neat:  The other day at Qwaq Craig Latta had
>>> a VM crash while running in a Parallels Linux VM under gdb.  He was able to
>>> give me a copy of the VM snapshot at the point where gdb stopped the
>>> process, giving me the opportunity to debug the live app at my leisure.  A
>>> cool idea.
>>>
>>
>> In other words, he was already running the Qwaq VM under gdb, so when the
>> Qwaq VM crashed (and left him at a gdb prompt), he simply suspended the
>> Parallels Linux VM and sent you a copy of the suspended Parallels Linux VM.
>>  Is that right?
>
>
> Right.  Very nice, as the patient is on the table.
>
>
> Yeah, full OS virtualization has some pretty cool use cases.
>
> David
>
>
>
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.squeakfoundation.org/pipermail/squeak-dev/attachments/20090826/5a1f3117/attachment.htm


More information about the Squeak-dev mailing list