Mark Payne created NIFI-8212:
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Summary: 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
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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