I'm working on a custom module, installed on a fresh DNN 4.9.1 install.  The module works fine in all respects until you turn on the cache (Module Settings -> Page Settings -> Cache Time (secs): ).  Once you set that to a non-zero number and visit the page while NOT logged in, the framework attempts to load the page over and over until either the DB connection pool is saturated or (if you turn off all db access in the module) the stack overflows.

I have debugged this through VS2005/IIS and there are no exceptions being thrown, but as soon as you step all the way through the Page_Load method and continue, it drops right back to the breakpoint at the top of the Page_Load.  Same thing for Page_Init, even if you exit sub directly after the InitializeComponent() method call.

I'm at a complete loss... can someone intimate familiar with the DNN cacheing mechanics shed some light on this issue?  As far as I can tell there are no errors being thrown from the cacheing code or the module code, yet the page continues to reload until it simply can't do so anymore.  This only happens when NOT logged in... the module loads fine logged in as host or admin even with the cache settings turned on.

Hopefully someone out there has a magic bullet :)

Thanks

-Matt Everett
 

Module output caching cannot be enabled (by setting the Cache Duration to a non-zero value) if interactive controls need to be available to a user who does not have edit permissions on the module. Output caching is automatically disabled for host/admin and users with edit permissions on the module.

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Bill, WESNet Designs
Team Lead - DotNetNuke Gallery Module Project (Not Actively Being Developed)
Extensions Forge Projects . . .
Current: UserExport, ContentDeJour, ePrayer, DNN NewsTicker, By Invitation
Coming Soon: FRBO-For Rent By Owner

Well, as it turns out, there was a little more going on behind the scenes that was causing the problem.

Basically, the main ascx control dynamically loads another ascx that provides a configurabe template.  In the code, that ascx was being assigned the module settings of the parent control using a line like this:

oTemplate = LoadControl("Templates/template1.ascx")
oTemplate.ModuleSettings = Me.ModuleSettings

Due to the way PortalModuleBase flags a module as cached (line 674, PortalModuleBase.vb) by inverting the CacheTime parameter, and the fact that both instances now held a reference to the _same_ ModuleSettings object, they continually inverted the parameter, so the page reloaded infinitely.

Once we had determined that, the fix was pretty simple.  Use a clone of the module settings object so that the caching mechanism in PortalModule base doesn't re-invert it's cachetime over and over again.

oTemplate.ModuleSettings = Me.ModuleSettings.Clone()

Problem solved... and more internal DNN knowledge gained.  Yay!