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https://issues.apache.org/jira/browse/UIMA-2977?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13708106#comment-13708106
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Marshall Schor commented on UIMA-2977:
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Analysis Engine do not automatically have their destroy methods called for the
event "when the component is disposed of"; UIMA doesn't have a formal concept
of this event. For instance, one could do the following with the UIMA
Application APIs: Read in a descriptor, create an analysis engine, send it
some CASes and do something with the results, and then terminate. In this
scenario, no "destroy" would be called; it's up to the surrounding application
code to call (or not) the destroy() method.
When the destroy method is called on an annotator, the framework does takes
care of propagating this to its delegates. However it doesn't propagate to any
shared resources that might have been loaded and set up; because they're
shared, they conceivably could still be in use by other annotators which were
not destroyed.
If some piece of user application code had a reference to a resource (not an
annotator, but an External Resource), then, that code *could* call the destroy
method on that resource.
In order to implement a fix for this Jira, one would need to define another
layer of lifecycle management for UIMA, I think, in order to be able to
reliably determine when a (shared) resource was no longer needed. A
counter-example use case for doing, for instance, a reference-counting scheme
for determining when to call destroy that relied on determining when *all* the
annotators that had linked to it had been destroyed, could be:
1) The top application sets up some UIMA pipelines to act as services. Some of
these load (via external resources), some large, slow-to-load resources, and
share them.
2) The top application needs to remain "responsive", but is able to shut down
some of its loaded pipelines, in response to changing user requests (load). If
at some point, it shutdown all of its pipelines, and then got some more user
requests, it might want to quickly startup some pipelines, but avoid the load
time of (some of) the external resources - so it might *choose* to keep these
loaded.
> destroy method of shared resources never called
> -----------------------------------------------
>
> Key: UIMA-2977
> URL: https://issues.apache.org/jira/browse/UIMA-2977
> Project: UIMA
> Issue Type: Bug
> Components: Core Java Framework
> Reporter: Richard Eckart de Castilho
>
> Apparently the ResourceManager and the resources created by the manager do
> not participate in the usual component life cycle. On other components, such
> as analysis engines or readers, the destroy() method is called when the
> component is disposed of. External resources never get notified when they are
> no longer needed. At least any resources derived from Resource (e.g.
> DataResource and ParametrizedDataResource) should be notified. The
> SharedResourceObject interface does not define any such life cycle callback.
> As a side-note: An alternative to the rather heavy-weight Resource interface
> of UIMA maybe be small life cycle interfaces such as the Spring
> InitializingBean and DisposableBean interfaces, or Java annotations marking
> initialization and destruction methods (e.g. @PostConstruct and @PreDestroy).
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