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From "Richard S. Hall" <he...@ungoverned.org>
Subject Re: [Discuss]About "Unable to acquire global lock for resolve"
Date Tue, 17 Dec 2013 13:25:44 GMT
On 12/17/13, 04:36 , Tang Yong wrote:
> Hi All,
>
> I met an issue as the following,
>
> ...
> Caused by: org.osgi.framework.BundleException: Unable to acquire global
> lock for resolve.
> 	at org.apache.felix.framework.Felix.resolveBundleRevision(Felix.java:3832)
> 	at org.apache.felix.framework.Felix.startBundle(Felix.java:1868)
> 	at org.apache.felix.framework.BundleImpl.start(BundleImpl.java:944)
> ...
>
> Richard said the issue is not a bug[1] of felix, and I also agree with him.
>
> However, I want to say once we truely met the issue and try to catch the
> exception on upper layer, how can we do?
>
> I think that best way should be: felix offered some api to let us
> retrieve whether bundle lock has been released by other thread.
>
> The second way can be: do a loop and wait for the changing of current
> bundle state, and set a timeout to avoid infinite loop.
>
> The third way should be: adjusting upper layer's bundles and decoupling
> them to avoid the case...
>
> Want to listen your ideas.

The main way I'd like to address this issue is to simply avoid it by
eliminating the use of the global lock altogether. What I had thought
about long ago was to simply make resolving optimistic so that it would
work on a copy of the framework state and if the framework state changed
at the end of the resolve, it would try to resolve again until the
framework state didn't change (perhaps with a retry limit).

The only other place that uses the global lock is for refreshing, but we
could probably eliminate it there in a somewhat similar fashion by
calculating all needed bundle locks in advance and locking all bundles
individually (you'd still need to double check the calculation to make
sure nothing changed and potentially release and try again).

-> richard

>
> [1]:http://mail-archives.apache.org/mod_mbox/felix-users/201102.mbox/%3C4D498058.7080104@ungoverned.org%3E
>
> Thanks
> Tang
>


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