(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 <[email protected]
<mailto:[email protected]>> 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 <http://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
