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https://issues.apache.org/jira/browse/NIFI-8212?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Mark Payne reopened NIFI-8212:
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Reopened because I found an issue: When a temp component is created, the
appropriate NAR ClassLoader is being used to locate the class but not being set
as the context class loader. As a result, if the constructor or any static code
in the component or in the initialization requires the NAR ClassLoader to be
the context class loader, it fails.
> Improve startup times for Stateless
> -----------------------------------
>
> Key: NIFI-8212
> URL: https://issues.apache.org/jira/browse/NIFI-8212
> Project: Apache NiFi
> Issue Type: Improvement
> Components: Core Framework, NiFi Stateless
> Reporter: Mark Payne
> Assignee: Mark Payne
> Priority: Major
> Fix For: 1.14.0, 1.13.1
>
> Time Spent: 5h
> Remaining Estimate: 0h
>
> There are a handful of things that happen in NiFi (and stateless) startup
> that take quite a while that can be improved:
> * We unpack all NAR's if they are not already unpacked. If they are
> unpacked, we perform a hash of the nar to ensure that it matches with what
> was unpacked. With stateless, though, we download nars on demand and name
> them a temporary file until the download completes, then rename them. As a
> result, we don't expect any hash conflicts unless it's a SNAPSHOT nar. We
> should avoid calculating hashes against all of the nars on startup.
> * We use the ServiceLoader to load all extensions. Given the number of
> extensions that we have and the prevalence of things like ObjectMapper as
> member variables, this can be rather expensive. We should instead just read
> the ServiceLoader file and create the objects on-demand. The temp components
> are needed for generating documentation, for example. But otherwise they are
> not needed. And stateless doesn't bother generating docs (since there's no UI
> to view them). This avoids creating lots of expensive objects and can also
> prevent loading huge numbers of classes into memory.
> * StringEncryptor is almost never used in stateless. We should lazy load it
> if needed.
> * Controller Service enabling is very slow in stateless. Currently, it
> asynchronously starts all services. Then it keeps polling to see if services
> are enabled and if not sleeps for a short period. We should instead move to a
> method of using Futures or wait/notify, etc. so that service enablement can
> completely quickly.
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