[development] No suitable nodes available at RackspaceCloud (Mosso)

Tomáš Fülöpp (vacilando.org) tomi at vacilando.org
Thu Feb 18 16:38:59 UTC 2010

(Interesting, Brian; I also were promised shell pretty soon about a year
ago. It's a shame - MediaTemple has shell *and *also a breakdown of compute
cycles per script...)

Anyway -- Victor's note about shortening PHP timeout brought me to thinking
about measuring the time since the start of the execution and issuing
flush() each time the process might time out.

Two questions:

   1. what is the most suitable Drupal function for this -- it needs to be
   something that runs regularly and for all kind of pages
   2. for Drupal, is it enough to issue flush() or is ob_end_flush() also
   needed, or something else

Thanks a million for any ideas;

Tomáš / Vacilando

On Thu, Feb 18, 2010 at 15:46, Brian Vuyk <brian at brianvuyk.com> wrote:

>  I've run into this with a few of my client sites, but they haven't even
> been high-traffic sites.
> Personally, I just don't think the RS Cloud is a good match for Drupal.
> Combine that with the recent security issues they've had, occasional
> inexplicable downtime, the 'no suitable nodes' and the lack of a shell, and
> I am moving my sites away as quick as I can.
> The shell issue is really sensitive for me - about 14 months ago, my
> previous host ran into... issues... and could no longer offer hosting. So, I
> was in a pinch and Rackspace (then Mosso) looked very good apart from the
> lack of a shell. I talked to their customer service reps, and was informed
> that shell access for the cloud was in pre-release testing, and was
> scheduled to go live the next week.
> In a burst of poor judgement, I decided that the package they offered was
> good enough to do without shell access for a week, so I bought in, and
> transferred my sites. 14 months later, shell access still hasn't been
> released, and I've had to move all my more critical  / development-intensive
> sites off of their service in the meantime.
> Brian
> Tomáš Fülöpp (vacilando.org) wrote:
> Hi,
> At RackspaceCloud (former Mosso) I've been plagued with a very unfortunate
> problem that i crippling both my work and the work of my clients -- namely
> the infamous error message "Unfortunately there were no suitable nodes
> available to serve this request." Those of you at RS Cloud must have bumped
> into it. It is cryptic and happens unpredictably. The cloud is very stable
> and scalable, but for any a little bit heavier Drupal installation people do
> start getting these errors.
> *Basically, it is a generic error thrown by load balanced systems that
> occurs as a result of a script exceeding a maximum timeout value (not the
> PHP timeout value!) If a client connection does not receive a response from
> the server after approximately 30 to 60 seconds the load balancer will close
> the connection and the client will immediately receive the error message. In
> most cases, the script will continue to execute until it reaches completion,
> throws an error, or times out on the server, but the client will not see the
> page load as expected and will instead receive this error.*
> I've used Boost for anonymous pages, Parallel, Memcache, etc., all of which
> helped and anonymous users *usually* don't get this error. The problem is
> with admin or any other a bit heavier work of logged in users. Even for
> basic Drupal websites with not too many modules! Pages like the list of
> modules, or the status page, i.e. heavy database or file requests, or API
> calls in PHP, are very likely to time out.
> Over the past year I've had a number of discussions with techs and admins
> at that cloud, but the situation is unresolved. They recognize the problem
> but maintain this is due to the special/unusual setup they use for their
> cloud. It is not a problem for some other CMS / frameworks. E.g. a very
> heavy MediaWiki installation runs just fine. Drupal seems to be less
> compatible with their system, somehow, somewhere.
> *Now, why do I mention all this in the development list? I've been
> intrigued by one little ray of hope in their words: "if a client connection
> does not receive a response from the server after approximately 30 to 60
> seconds the load balancer will close the connection and the client will
> immediately receive the error message". Their techs said if I were able to
> emit any kind of intermediary response to the client during rendering of
> the page, then this would be solved. *
> Indeed, a bit like the Batch API works in Drupal (with that I often run
> night-long scripts without problems). I wonder, maybe this is a more generic
> problem for any system that employs load balancers?
> *So my questions to you, colleagues, is -- do you see any place in Drupal
> processing chain that could be used, and approximately how, to make sure
> that the load balancer keeps the connection opened.* If you have any
> ideas, wild or proven, I will be happy to test and develop them further and
> bring them back to the community, of course. If this succeeds, I think many
> of us will be relieved (and able to focus on development again!)
> Thank you for any ideas - on and off this list.
> Best regards,
> Tomáš / Vacilando
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