videos not playing simultaneously

Had a reply of the post on Stackoverflow.com where,

Mr. Marc B replied as follows,

PHP file-based sessions will lock the session file while a request is active. If you intend to use parallel requests like this, you'll have to make sure each script closes the session as soon as possible (ie: after writing out any changes) with session_write_close() to keep the lock time to a minimum.

I checked the files responsible for streaming videos in KalturaCE because streaming is where it hangs the other request and ended up with the following files.

/var/www/kalturace/kaltura/alpha/apps/kaltura/modules/keditorservices/templates/flvclipperSuccess.php
/var/www/kalturace/kaltura/alpha/apps/kaltura/modules/keditorservices/templates/flvproviderSuccess.php

so I added the line,

session_write_close();

at the end of both scripts before

 die; // prevent symfony from sending its headers and filling our logs with warnings

BUT, it isn't working for me :(

Moreover, on the issue tracker of Kaltura Drupal Module on drupal.org
G Robot advised me as follows,

Would be interesting to know if this affects multiple client browsers on the same machine, multiple client machines, etc.

Cheers

Therefore I am off to the suggestions given above and would be posting back till I resolve the said issue.

The session suggestion is valid too, but to resolve that you'd need to close the session before the streaming initiates, not once it's completed.

I can't find your question on StackOverflow. Want to post a link here, and let us know how the suggestions I made fared? Would be interesting to see what other ideas were put forward.

Drupal.org issue: http://drupal.org/node/1002144 (which I closed as I believe this is not a Drupal issue, but adding URL for reference)
Earlier post by yourself: http://www.kaltura.org/videos-not-playing-simultaneously

@grobot ✿ www.giantrobot.co.nz

Since you say that if you download from different browsers it works well, this actually sounds like a client side browser limitation.

There is a limitation of parallel objects requested from the same domain.
More information - http://www.websiteoptimization.com/speed/tweak/parallel/

We use a technique to overcome this on the editors side where you can define multiple subdomains that redirect to the same domain and ask the editors to append a number to the subdomain (so www0, www1, www2, etc. are all redirecting to same www subdomain).

To test this is actually the problem, try this:
Define in your apache conf ServerAlias www0.mydomain.com (replace with whatever) and then point your browser as follow:
www.mydomain.com /kalturace/p/1/sp/100/flvclipper/entry_id/xxxxxx/flavor/1/version/100000
www0.mydomain.com /kalturace/p/1/sp/100/flvclipper/entry_id/xxxxxx/flavor/1/version/100000

If that works, then the problem you have is with the client browser limitation and not in the server.

Let us know how it works (or if it didn't).

Check out the hashURLforMultipalDomains in the URLProccessing class used by the editors.

Does increase in hardware resources would change this behavior?

By the grace of Almighty Allah, atlast I did it.

Though did it in probably an indecent way but it worked for me.

The track I followed was as follows,

NOTE: I am using KalturaCE 1.5 and KDP 2.5

Having the very very first advice at stackoverflow and suggestions here from GRobot and Kalturian in mind.

With the help of HTTP watch I traced that every time when flvclipper services are called to serve a flv file from the server it sends a redirect to the client which gave me a clue to replace the logic of of redirection in a way that it can replace subdomains for a particular session.

So to add different subdomains to the redirection URL of flv file I did as follows.
In MyKalturCEDirectory/kaltura/alpha/apps/kaltura/modules/keditorservices/actions/flvclipperAction.class.php

I put the following code before sending redirect headers to the client at line 272,


session_start();
if(isset($_SESSION['subDomainPostFix']))
$_SESSION['subDomainPostFix'] = $_SESSION['currentDomainForFLV']+ 1;
if($_SESSION['subDomainPostFix'] === 3) // since I have a subdomain sequence defined as c0,c1,c2
$_SESSION['subDomainPostFix'] = 0;
else
$_SESSION['subDomainPostFix'] = 0;

and added the added the domain in the header() call.

After this amendment flv file were serving from different domains but AGAIN my calls to server stuck at retrieving widget UIConf from the server, if a big video is running already.

Therefore, I reached to conclusion that there should be a session_write_close(); call placed after the above code.


session_start();
if(isset($_SESSION['subDomainPostFix']))
$_SESSION['subDomainPostFix'] = $_SESSION['currentDomainForFLV']+ 1;
if($_SESSION['subDomainPostFix'] === 3) // since I have a subdomain sequence defined as c0,c1,c2
$_SESSION['subDomainPostFix'] = 0;
else
$_SESSION['subDomainPostFix'] = 0;

BUT AGAIN, I didn't succeed and stuck at the same call when KDP tries to receive Widget UIConf from the server when a video is already buffering. It led me to another conclusion that I should have to place the session_write_close(); call to the point when the server is about to start the streaming of the flv file.

My suspect were two files,

MyKalturCEDirectory/kaltura/alpha/apps/kaltura/modules/keditorservices/templates/flvclipperSuccess.php
MyKalturCEDirectory/kaltura/alpha/apps/kaltura/modules/keditorservices/templates/flvproviderSuccess.php

I put session_write_close(); call in both files as follows, respectively,


//flvclipperSuccess.php
session_write_close();

die;



//flvproviderSuccess.php
$flv_streamer->printMetadata();
session_write_close(); //Fuad Edit
$flv_streamer->streamFlv();

die;


AND BINGOO!!! it started to work fine. I tested it with around 3 videos running simultaneously and it worked all well.

Thanks All for your kind advices.