Lazy initialization of plugins
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Key: FELIX-2246
URL: https://issues.apache.org/jira/browse/FELIX-2246
Project: Felix
Issue Type: Improvement
Components: Web Console
Affects Versions: webconsole-3.0.0
Reporter: Valentin Valchev
Attachments: lazy-webconsole-plugins.jude
Here at ProSyst we use a small trick to delay initialization of our services:
When the service is quite big, and loads many resources (incl. too many
classes), we register not a service, but a ServiceFactory instead. With that
factory we delay the instantiation of the service, when it is actually needed
and obtained by other bundle.
Yes, this makes the code a little bit more complex, but it greatly improves the
start-up time and the overall memory usage.
This can be applied to webconsole plugins too. My idea is that Web Console
should only track Service Reference without actually obtaining the service
itself [not getService()].
When the user makes request the WebConsole calls the factory to create
instance. Instance is created and returned to the Web Console, which uses it to
generate content for the request.
This way a plugin is actually not initialized until it is really used. Only
small portion of classes, from the bundle are initialized.
Unfortunately the ServiceTracker, when notified for added service obtains the
real service object. So it might be better to use directly ServiceListener for
the plugins.
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