[Catalyst] Force the session to be saved.

[Duncan Garland]

Hi,

The sessions are in a standard Oracle table in which the primary key is the session id and the session data is a blob. The session should be retrieving the correct data. I think we'd have noticed long before now if the data wasn't be committed properly. (Autocommit is on anyway.)

Under the original setup we delete the key for the javascript template after using it (eg $c->session->{javascript}->{template1}). This morning I removed the delete statement. The problem still occurred.

I dug a bit more and it seems that the session occasionally completely loses its javascript key. (Same session id.)

I reduced the number of fastcgi processes from 5 to 1 and the problem went away.

This may mean that the race condition doesn't show up with one process.

However it may mean that the processes don't coordinate properly.

Should we have done something to make the session handling more sophisticated when we increased the number of fastcgi processes? For example do we have to do something explicit to lock a particular session to a particular process?

Regards

Duncan

 
-----Original Message-----
From: Andrew Rodland [mailto:andrew at cleverdomain.org] 
Sent: 29 March 2011 19:33
To: The elegant MVC web framework
Subject: Re: [Catalyst] Force the session to be saved.

On Tuesday, March 29, 2011 12:46:32 PM Duncan Garland wrote:
> Hi,
> 
> We've been having some peculiar behaviour from our system. I think it's
> because the controller which produces the HTML page stores data in the
> session for retrieval by the controller which produces the associated
> javascript file.
> 
> The client begins processing the HTML page as soon as it starts to arrive.
> When it reaches the script tag it requests the javascript page.
> Occasionally the first controller hasn't written the session to the
> database when the javascript controller tries to retrieve it.
> (Catalyst::Plugin::Session::Store::DBIC).
> 
> I can move the script tag down the page a bit, but what I really need is a
> way to force the session to be written before the HTML template is
> rendered.
> 
> Something like:
> 
> $c->session->{javascript}->{$template}  = { one = 1, two => 2};
> $c->session->save;
> 
> Is there such a method?
> 
> Regards
> 
> Duncan

finalize_session (which writes the session to the DB) runs before 
finalize_body (which writes the response to the client), so Catalyst already 
does what you would like it to, and forcing a session write before running the 
view is unlikely to help anything. I suspect either your database isn't 
guaranteeing ordering, or the problem is somewhere other than where you're 
looking.

Andrew

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