[FELIX-6155] Add caching of service component metadata

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: scr-2.1.16
• Fix Version/s: scr-2.1.18
• Component/s: Declarative Services (SCR)
• Assignee: Tom Watson
• Reporter: Tom Watson
• Created: 02/Jul/19 17:06
• Updated: 30/Nov/20 14:49
• Resolved: 30/Nov/20 14:49

Description

SCR has to discover and parse the component XML files of all bundles that have the Service-Component header. In a configuration that has a significant number of bundles using SCR this overhead begins to add up. For modest number of bundles (~300) I see this taking nearly 200 ms in an overall application launch time of 3000 ms.

This overhead can be greatly reduced if we cached the component metadata such that on restart the XML files do not need to be discovered or parsed, or even having to look for the Service-Component header in all active bundles. I am working on a caching implementation that I would like to contribute which I plan to have disabled by default so we can experiment with enabling such a cache for cases where a relaunch performance time is critical.