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Let me start out by saying this proposal doesn't propose that support be dropped for IMultithreaded interfaces. This proposal does propose that they should be marked as deprecated and over time as appropriate IMultithreaded channels should be rewritten to use IChannel insteadrefactored as Channels or Portlets. Eventually there might come a time when most current IMultithreadedChannel implementations have dropped IMultithreaded and we can simplify and improve the performance of uPortal by dropping support for this interface, but there are no near term plans to drop that support. Also, we need to make it clear that IMultithreaded* channels shouldn't be perceived as a better, faster more optimized way of developing a channel.

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IMulithreaded re-invents this. IMultithreaded asks the portal to guarantee that all boxes using this channel will be backed by the same IMultithreaded instance, such that the instance fields in that channel instance are shared across all usages of the channel. This is completely equivalent to writing an IChannel and placing those shared objects in static fields. It's an increasing best practice to avoid the use of static fields, which are well understood – - it should be even more a best practice to avoid the use of an equivalent facility that is much less well understood.

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There are no important advantages of IMultithreaded* to be had, and there are real costs of implementing this interface. It is clear that we should discourage implementation of channels as IMultithreaded*, and I think deprecating the interfaces is the clearest way to communicate this without ambiguity.

Proposal Implementation

• Fix Apply patch attached to UP-1362: Allow multiple threads to concurrently instantiate channels
• Mark all IMultithreaded* interfaces in uPortal 2.4.-patches, 2.5-patches and 2.6 HEAD as deprecated.
  • IMultithreadedCacheable
  • IMultithreadedChannel
  • IMultithreadedCharacterChannel
  • IMultithreadedDirectResponse
  • IMultithreadedMimeResponse
  • IMultithreadedPrivileged

• Discourage use of these deprecated APIs
• Refactor the core channels to implement IChannel* .
  • These framework channels implement one of the IMultithreaded* interfaces:
    • CGroupsManager (Patch attached to UP-1371)
    • CPortletAdapter (Patch attached to UP-1300)
    • CWebProxy (Patch attached to UP-1302)
    • CApplet (Patch attached to UP-1369)
    • CGenericXSLT (Patch attached to UP-1303)
    • CImage (Patch attached to UP-1367)
    • CInlineFrame (Patch attached to UP-1368)
    • CPersonAttributes (Patch attached to UP-1370)
• Adopt a policy that no new channels implementing IMultithreaded*will be accepted into the framework (uPortal source tree)
• Propose a presentation for JA-SIG Vancouver conference "Why IMultithreaded is Deprecated and How to Refactor Your Channels away from IMultithreaded"