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https://issues.apache.org/jira/browse/FELIX-4692?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14254007#comment-14254007
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Richard S. Hall commented on FELIX-4692:
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Looking at the code of CapabilitySet.match(Set<> caps, SimpleFilter sf) on line
239 we do "matches.retainAll(caps)" which in your case caps would be your 10k
services, so I expect that this is where you see the slowdown.
We have to do the retainAll() because it gives us the intersection of matches
from the index and all other capabilities that have been matched by any other
part of the filter up until this point (i.e., since this is recursive due to
expression nesting). However, it is certainly the case that the very first time
through (i.e., at the top level), we don't need to do retainAll() because by
definition caps would already be m_capSet, which is all available capabilities.
So, perhaps the simple optimization is to simply check if (caps == m_capSet)
and if so don't do retain all.
> Improve Service access time
> ---------------------------
>
> Key: FELIX-4692
> URL: https://issues.apache.org/jira/browse/FELIX-4692
> Project: Felix
> Issue Type: Improvement
> Components: Framework
> Affects Versions: framework-4.4.1
> Reporter: Felix Meschberger
> Assignee: Felix Meschberger
> Fix For: framework-4.6.0
>
> Attachments: FELIX-4692.diff
>
>
> Currently the ServiceRegistry takes roughly 1ms to access a single service.
> In a reasonably large system, this may over time consume considerable time.
> For example in our inhouse system sporting roughly 5000 services with 15'000
> service accesses during startup, these accesses acount for almost 15 seconds
> or roughly 25-30% of the total startup time.
> Internally all accesses to services are handled with a Filter even if the
> service is simply retrieved with the service name without a filter. This
> causes a considerable overhead.
> A simple improvement is to keep services not only in a global Capabitliy Set
> accessible through generic filters but also keep such a set for each
> registered service name.
> The measured improvement of this change is substantial: accessing these
> 15'000 services now only takes roughly 3 seconds or 0.2 ms per service or 5
> times faster.
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