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Performance and concurrency of calls into services [message #926453] Fri, 28 September 2012 13:14 Go to next message
Rich Mayfield is currently offline Rich Mayfield
Messages: 44
Registered: August 2010
Member
We ran into the problem described in

https://bugs.eclipse.org/bugs/show_bug.cgi?id=377198

where our bundle's code calls into a service that is resolved via Gemini Blueprint. The code is multi-threaded and invokes methods on that service often.

In short, the synchronization around service lookups in Gemini Blueprint appears to be a huge, huge bottleneck. At this point we're basically going to have to tell our developers to avoid Gemini Blueprint in many circumstances when it comes to wiring together services and references to those services.

Is there a way around this? Short of resolving the bug (granted, the solution proposed in the bug may not be correct), what is the recommended way to go?

Thanks again,
rich
Re: Performance and concurrency of calls into services [message #929100 is a reply to message #926453] Mon, 01 October 2012 04:12 Go to previous messageGo to next message
Glyn Normington is currently offline Glyn Normington
Messages: 1222
Registered: July 2009
Senior Member
The only clean solution I can think of is to fix that bug or patch Gemini Blueprint with some code based on the proposed solution. The proposed solution looks plausible, but I haven't checked the code to see if the service holder is volatile and is cleared if the service goes away.

An obvious workaround, which may not be acceptable, is to code a method on the service interface which returns the service object. Then any performance/scalability sensitive caller can get hold of the service object directly and avoid all overheads and bottlenecks. Of course, this would go pear-shaped if you need to stop the service and have those callers react appropriately. But, depending on the design of your bundles and how their lifecycles behave and coordinate, this may be a suitable workaround.
Re: Performance and concurrency of calls into services [message #929704 is a reply to message #929100] Mon, 01 October 2012 13:28 Go to previous messageGo to next message
Rich Mayfield is currently offline Rich Mayfield
Messages: 44
Registered: August 2010
Member
Thanks for the idea in terms of a workaround. In the absence of a fix we'll likely need just not use Blueprint for high traffic services. My next concern then is that we may discover that a number of our services start to run into this as we scale up.
Re: Performance and concurrency of calls into services [message #930300 is a reply to message #929704] Tue, 02 October 2012 03:27 Go to previous messageGo to next message
Glyn Normington is currently offline Glyn Normington
Messages: 1222
Registered: July 2009
Senior Member
Fair enough. I think the raw pathlength of calls to Blueprint services is also likely to be an issue for performance sensitive services. I wonder if Declarative Services is more appropriate because of its lack of service damping and presumably therefore proxying?
Re: Performance and concurrency of calls into services [message #930900 is a reply to message #930300] Tue, 02 October 2012 14:48 Go to previous message
Rich Mayfield is currently offline Rich Mayfield
Messages: 44
Registered: August 2010
Member
I went from programmatically dealing with services directly to Blueprint services, so never delved into Declarative Services. Lemme see if I understand what you're suggesting.

Given: bundle A consumes service X provided by bundle B:

Would I just need to change the way that bundle B declares service X (and not change bundle A at all, which would still use Blueprint)?

or...

Would I need to (also) change the way that bundle A is wired to service X?

That is, do we need to provide *and* consume through Declarative Services in order to avoid the synchronization?

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