[tdwg-tapir] TAPIRLink and memory

Renato De Giovanni renato at cria.org.br
Wed Aug 1 18:21:24 CEST 2007

Hi Roger,

I do think it's worth adding your changes related to the "fopen" 
workaround. Please don't hesitate.

I should say that I'm actually surprised that TapirLink requires only 
10M with such a complex RDF output model. I wonder how many records 
were being returned in your request?

I also don't have much experience with profiling, but I'm sure 
there's room for improvements since I didn't pay much attention to 
optimization. By the way, the main new feature for the next version 
will be caching. I'm expecting significant improvements in 
performance since query templates, output models, and response 
structures will be all cached by default as serialized PHP. When 
TapirLink can use cached content, I suppose this will also reduce 
memory use. However, the first time it receives a particular output 
model in a request, then it will require the same memory if we don't 
make additional optimizations and if we want it to run below the 8M 

Anyway, I also wonder how many people and organizations will need to 
run a TAPIR provider software under the conditions you described 
(external ISP with such a low memory use limit). I still never heard 
of any case in our community (maybe someone from GBIF could give us a 
better picture?).

Best Regards,

On 1 Aug 2007 at 14:11, Roger Hyam wrote:

> Hi All
> I spent a couple of hours this morning adapting TAPIRLink so that it  
> uses a work around of fopen() because many ISPs will not support  
> opening remote files (there is a php config option to stop it).
> Anyhow I got past this and found that my output model still wouldn't  
> run on my ISP account (Easyspace.com) but would run on my local  
> machine. After a while I found that it was running out of memory.
> My ISP limits memory to 8meg per running script. That seems pretty  
> tight until you imagine having a hundred scripts running  
> simultaneously. It was the default setting prior to php 5.2 when it  
> jumped to 128meg! This may explain why ISPs are very slow to migrate  
> to PHP5.*
> The TAPIRLink request was using almost 10meg under PHP 5.2 according  
> to memory_get_peak_usage()  to parse the rather complex  
> TaxonOccurrence output model. There is no peak usage method on  
> earlier PHP versions. Ten meg seems quite reasonable considering the  
> cost of RAM these days - but there you have it.
> Anyhow I am nervous because this means that deployers might need to  
> mess with php.ini to get scripts running which means shared servers  
> may be problematic for deployments that use complex output models.  
> Basically it won't run everywhere php is available but only where php  
> in a certain config is available. It also means that if you are being  
> crawled by a 10 threaded robot you will be using close to 100meg to  
> service the requests plus memory allocation and deallocation etc.
> It is all seems pretty trivial if you have a newer machine and even  
> more so if you install PHP 5.2+ on it but it does mean that that old  
> departmental webserver that has an old install of PHP on may not run  
> the RDF based output models out of the box.
> Never done any profiling with PHP and wouldn't like to get into it. I  
> guess Python will have a similar memory footprint as it is doing a  
> similar job but the install scenario is different for PyWrapper - you  
> really need shell access.
> It may not be worth adding the fopen() work round if the deployment  
> environment requires access to php.ini.
> Would be grateful for your thoughts on this.
> Roger

More information about the tdwg-tag mailing list