Re: Confused about two development utils [EXT]

James would you be able to share more info about your setup ?
1. What exactly is your application doing which requires so much memory and
CPU - is it something like gene splicing (no i don't know much about it
beyond Jurassic Park :D )
2. Do you feel Perl was the best choice for whatever you are doing and if
yes then why ? How much of your stuff is using mod_perl considering you
mentioned not much is web related ?
3. What are the challenges you are currently facing with your
implementation ?

On Wed, Dec 23, 2020 at 6:58 AM James Smith <[email protected]> wrote:

> Oh but memory is a problem – but not if you have just a small cluster of
> machines!
>
> Our boxes are larger than that – but they all run virtual machine {only a
> small proportion web related} – machines/memory would rapidly become in our
> data centre - we run VMWARE [995 hosts] and openstack [10,000s of hosts] +
> a selection of large memory machines {measured in TBs of memory per machine
> }.
>
> We would be looking at somewhere between 0.5 PB and 1 PB of memory – not
> just the price of buying that amount of memory - for many machines we need
> the fastest memory money can buy for the workload, but we would need a lot
> more CPUs then we currently have as we would need a larger amount of
> machines to have 64GB virtual machines {we would get 2 VMs per host. We
> currently have approx. 1-2000 CPUs running our hardware (last time I had a
> figure) – it would probably need to go to approximately 5-10,000!
> It is not just the initial outlay but the environmental and financial cost
> of running that number of machines, and finding space to run them without
> putting the cooling costs through the roof!! That is without considering
> what additional constraints on storage having the extra machines may have
> (at the last count a year ago we had over 30 PBytes of storage on side –
> and a large amount of offsite backup.
>
> We would also stretch the amount of power we can get from the national
> grid to power it all - we currently have 3 feeds from different part of the
> national grid (we are fortunately in position where this is possible) and
> the dedicated link we would need to add more power would be at least 50
> miles long!
>
> So - managing cores/memory is vitally important to us – moving to the
> cloud is an option we are looking at – but that is more than 4 times the
> price of our onsite set-up (with substantial discounts from AWS) and would
> require an upgrade of our existing link to the internet – which is
> currently 40Gbit of data (I think).
>
> Currently we are analysing a very large amounts of data directly linked to
> the current major world problem – this is why the UK is currently being
> isolated as we have discovered and can track a new strain, in near real
> time – other countries have no ability to do this – we in a day can and do
> handle, sequence and analyse more samples than the whole of France has
> sequenced since February. We probably don’t have more of the new variant
> strain than in other areas of the world – it is just that we know we have
> because of the amount of sequencing and analysis that we in the UK have
> done.
>
>
>
> *From:* Matthias Peng <[email protected]>
> *Sent:* 23 December 2020 12:02
> *To:* mod_perl list <[email protected]>
> *Subject:* Re: Confused about two development utils [EXT]
>
>
>
> Today memory is not serious problem, each of our server has 64GB memory.
>
>
>
>
> Forgot to add - so our FCGI servers need a lot (and I mean a lot) more
> memory than the mod_perl servers to serve the same level of content (just
> in case memory blows up with FCGI backends)
>
> -----Original Message-----
> From: James Smith <[email protected]>
> Sent: 23 December 2020 11:34
> To: André Warnier (tomcat/perl) <[email protected]>; [email protected]
> Subject: RE: Confused about two development utils [EXT]
>
>
> > This costs memory, and all the more since many perl modules are not
> thread-safe, so if you use them in your code, at this moment the only safe
> way to do it is to use the Apache httpd prefork model. This means that each
> Apache httpd child process has its own copy of the perl interpreter, which
> means that the memory used by this embedded perl interpreter has to be
> counted n times (as many times as there are Apache httpd child processes
> running at any one time).
>
> This isn’t quite true - if you load modules before the process forks then
> they can cleverly share the same parts of memory. It is useful to be able
> to "pre-load" core functionality which is used across all functions {this
> is the case in Linux anyway}. It also speeds up child process generation as
> the modules are already in memory and converted to byte code.
>
> One of the great advantages of mod_perl is Apache2::SizeLimit which can
> blow away large child process - and then if needed create new ones. This is
> not the case with some of the FCGI solutions as the individual processes
> can grow if there is a memory leak or a request that retrieves a large
> amount of content (even if not served), but perl can't give the memory
> back. So FCGI processes only get bigger and bigger and eventually blow up
> memory (or hit swap first)
>
>
>
>
>
> --
>  The Wellcome Sanger Institute is operated by Genome Research  Limited, a
> charity registered in England with number 1021457 and a  company registered
> in England with number 2742969, whose registered  office is 215 Euston
> Road, London, NW1 2 [google.com]
> <https://urldefense.proofpoint.com/v2/url?u=https-3A__www.google.com_maps_search_s-2B215-2BEuston-2BRoad-2C-2BLondon-2C-2BNW1-2B2-3Fentry-3Dgmail-26source-3Dg&d=DwMFaQ&c=D7ByGjS34AllFgecYw0iC6Zq7qlm8uclZFI0SqQnqBo&r=oH2yp0ge1ecj4oDX0XM7vQ&m=friR8ykiZ-NWYdX6SrbT_ogNXEVR-4ixdkrhy5khQjA&s=xU3F4xE2ugQuDWHZ4GtDn9mPBCKcJJOI0PYScsSNjSg&e=>
> BE.
>
>
>
> --
>  The Wellcome Sanger Institute is operated by Genome Research
>  Limited, a charity registered in England with number 1021457 and a
>  company registered in England with number 2742969, whose registered
>  office is 215 Euston Road, London, NW1 2 [google.com]
> <https://urldefense.proofpoint.com/v2/url?u=https-3A__www.google.com_maps_search_s-2B215-2BEuston-2BRoad-2C-2BLondon-2C-2BNW1-2B2-3Fentry-3Dgmail-26source-3Dg&d=DwMFaQ&c=D7ByGjS34AllFgecYw0iC6Zq7qlm8uclZFI0SqQnqBo&r=oH2yp0ge1ecj4oDX0XM7vQ&m=friR8ykiZ-NWYdX6SrbT_ogNXEVR-4ixdkrhy5khQjA&s=xU3F4xE2ugQuDWHZ4GtDn9mPBCKcJJOI0PYScsSNjSg&e=>
> BE.
>
> -- The Wellcome Sanger Institute is operated by Genome Research Limited, a
> charity registered in England with number 1021457 and a company registered
> in England with number 2742969, whose registered office is 215 Euston Road,
> London, NW1 2BE.
>