[Xerte-dev] Re: example_zipper issue revisited

Thu May 1 14:46:15 BST 2014

I will look into this, but I don't have much time at the moment. Perhaps 
topnight. Otherwise, it'll have to be next week.

Tom

Smith, John schreef op 1-5-2014 15:38:
> Well. Preliminary testing looks good with my new code but i haven't tested on Windows yet - would be interested in getting Tom's take on all of this...
>
> I just added loads of videos via ftp (upload limit set to 7M on this server) and checked the memory limit and it is
>
> memory_limit    90M     90M
>
> and with each video being used on a page then i've just successfully downloaded a 316Mb archive zip without any problems (it took several minutes too so the script didn't timeout) and was able to play the videos contained within... and this is just a cheap Dreamhost shared server, nothing fancy...
>
> On to Windoze...
>
> Regards,
>
> John Smith | Learning Technologist
> Room A251, Govan Mbeki Building | School of Health & Life Sciences | Glasgow Caledonian University
> Cowcaddens Road | Glasgow | G4 0BA
>
> Please address ALL support requests to hlsblt at gcu.ac.uk where one of the School Learning Technologists will pick up the job. This will ensure that all jobs are completed as promptly as possible.
> ________________________________________
> From: xerte-dev-bounces at lists.nottingham.ac.uk [xerte-dev-bounces at lists.nottingham.ac.uk] On Behalf Of Ron Mitchell [ronm at mitchellmedia.co.uk]
> Sent: 01 May 2014 10:58
> To: 'For Xerte technical developers'
> Subject: [Xerte-dev] Re: example_zipper issue revisited
>
> Hi John
> the problem is when I originally raised this issue on 8th April it coincided
> with discovering loads of these un-removed example_zipper files on the
> sandpit install. At that time I also mentioned the separate session issue as
> a reason I hadn't updated to a newer revision and I think you mentioned that
> you thought Tom had fixed this zipper issue in a later revision. So once
> we'd identified the cause of the session issue (or at least Julian's attempt
> at fixing his FF issue) I updated the sandpit code as well as other servers.
> Now I've been using the 2.1 branch for this rather than develop so I'm not
> sure if Tom's fix is in develop but not 2.1 but I think the code is the same
> at the moment.
>
> In short although I've been using a 62MB file from a project a user was
> unable to export, previously there were loads of these zipper files in loads
> of different user/project folders and there are probably quite a few again
> now prior to my changing the memory limit.
>
> I could try resetting the memory_limit back on my own server and test again
> but my previous tests with the 62MB file certainly weren't crashing the
> server. Let me know if you think its worth testing with larger files and the
> default 128MB limit or if your and David's later responses have ruled that
> out as being worthwhile?
>
> I know Tom said last night that he was going to revisit his fix for this so
> would be good to hear back from Tom once he's done that.
>
> Cheers
> Ron
>
> -----Original Message-----
> From: xerte-dev-bounces at lists.nottingham.ac.uk
> [mailto:xerte-dev-bounces at lists.nottingham.ac.uk] On Behalf Of Smith, John
> Sent: 01 May 2014 09:57
> To: For Xerte technical developers
> Subject: [Xerte-dev] Re: example_zipper issue revisited
>
> Hi Ron,
>
> Have been thinking about your issue and just wondering whether you might
> have inadvertently chosen the worst file size possible for the video with
> 128Mb memory available to PHP. Let me explain (and this is entirely
> hypothetical)...
>
> The zipper creates a blank object (<0.1Mb memory used) The library loads all
> the other files individually and zips them into the object (0Mb ->
> compressed size of all js/html is perhaps around 1-2Mb or under) The library
> then loads the mp4 (now it has the object = 2Mb and the video = 62Mb in
> memory) It adds it to the zip object but it's also still in memory (mp4
> doesn't compress at all so we have 2 + 62 + 62 =126Mb which is less than
> 128Mb) It then closes the connection to the mp4 and destroys the object
> (memory now = 64Mb for the zip)
>
> I'm wondering whether a 64 Mb or slightly bigger will cause you to be able
> to crash that server too. Is that something you could try?
>
> Regards,
>
> John Smith | Learning Technologist
> Room A251, Govan Mbeki Building | School of Health & Life Sciences | Glasgow
> Caledonian University Cowcaddens Road | Glasgow | G4 0BA
>
> Please address ALL support requests to hlsblt at gcu.ac.uk where one of the
> School Learning Technologists will pick up the job. This will ensure that
> all jobs are completed as promptly as possible.
> ________________________________________
> From: xerte-dev-bounces at lists.nottingham.ac.uk
> [xerte-dev-bounces at lists.nottingham.ac.uk] On Behalf Of Ron Mitchell
> [ronm at mitchellmedia.co.uk]
> Sent: 01 May 2014 09:09
> To: 'For Xerte technical developers'
> Subject: [Xerte-dev] Re: example_zipper issue revisited
>
> Hi John
> I was just going to test your export code on a server where I don't have
> access to change php settings so the memory limit is fixed at 128MB. I know
> what David means that ideally we want cross platform code but as you say
> there are inevitably different solutions/restrictions for some e.g. no
> control over memory limit. In fact the upload limit on this particular
> shared server is set at the default 2MB so I had to upload the test 62MB mp4
> via ftp. However I'm now confused further because this is the same XOT code
> as the other servers I was using for testing so I expected the export to
> fail when testing before replacing the export code with yours and yet it
> didn't fail and I was able to download the zip which didn't contain any
> example_zipper files.
>
> I'm glad you're able to reproduce the issue but not sure how a server with
> 128MB memory limit is able to export ok without a change of code or memory
> limit :-(
>
>
>
> -----Original Message-----
> From: xerte-dev-bounces at lists.nottingham.ac.uk
> [mailto:xerte-dev-bounces at lists.nottingham.ac.uk] On Behalf Of Smith, John
> Sent: 01 May 2014 08:38
> To: xerte-dev at lists.nottingham.ac.uk
> Subject: [Xerte-dev] Re: example_zipper issue revisited
>
> All i know Dave is that, with the commented code uncommented, my system
> couldn't download a 56Mb an 79Mb zip but with this code 79Mb came down no
> problem.
>
> We may have to use what we have access to on different systems. There may be
> a similar way to pipe the result into windows or we fall back to the old
> code and crank the memory requirements up yo 300Mb which not everyone can
> most likely do anyway...
>
> Regards
>
> John Smith
> Learning Technologist
> School of Health and Life Sciences
>
> Sent from Samsung Galaxy SII
>
>
>
> David Goodwin <david at palepurple.co.uk> wrote:
>
>
>
> <snip>
> Uses the unix command zip and pipes the stream back into PHP in 8192 chunks
>
> <snip>
> Also, might not work on Windows...
>
> So therefore it's not worth using?
>
>
> Technically there is no benefit to doing the fread(....) over a
> fpassthru(...) fpassthru does something like 8192 chunks internally.
>
>
> David.
>
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