Gus Heck created SOLR-13457:
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Summary: Managing Timeout values in Solr
Key: SOLR-13457
URL: https://issues.apache.org/jira/browse/SOLR-13457
Project: Solr
Issue Type: Improvement
Security Level: Public (Default Security Level. Issues are Public)
Affects Versions: master (9.0)
Reporter: Gus Heck
Presently, Solr has a variety of timeouts for various connections or
operations. These timeouts have been added, tweaked and refined and in some
cases made configurable in an ad-hoc manner by the contributors of individual
features. Throughout the history of the project. This is all well and good
until one experiences a timeout during an otherwise valid use case and needs to
adjust it.
This has also made managing timeouts in unit tests "interesting" as noted in
SOLR-13389.
Probably nobody has the spare time to do a tour de force through the code and
coordinate every single timeout, so in this ticket I'd like to establish a
framework for categorizing time outs, a standard for how we make each category
configurable, and then add sub-tickets to address individual timeouts.
The intention is that eventually, there will be no "magic number" timeout
values in code, and one can predict where to find the configuration for a
timeout by determining it's category.
Initial strawman categories (feel free to knock down or suggest alternatives):
# *Feature-Instance Timeout*: Timeouts that relate to a particular
instantiation of a feature, for example a database connection timeout for a
connection to a particular database by DIH. These should be set in the
configuration of that instance.
# *Optional Feature Timeout*: A timeout that only has meaning in the context
of a particular feature that is not required for solr to function... i.e.
something that can be turned on or off. Perhaps a timeout for communication
with an external ldap for authentication purposes. These should be configured
in the same configuration that enables this feature.
# *Global System Timeout*: A timeout that will always be an active part of
Solr these should be configured in a new <timeouts> section of solr.xml. For
example the Jetty thread idle timeout, or the default timeout for http calls
between nodes.
# *Node Specific Timeout*: A timeout which may differ on different nodes. I
don't know of any of these, but I'll grant the possibility. These (and only
these) should be set by setting system properties. If we don't have any of
these, that's just fine :).
*Note that in no case is a hard-coded value the correct solution.*
If we get a consensus on categories and their locations, then the next step is
to begin adding sub tickets to bring specific timeouts into compliance. Every
such ticket should include an update to the section of the ref guide
documenting the configuration to which the timeout has been added (e.g. docs
for solr.xml for Global System Timeouts) describing what exactly is affected by
the timeout, the maximum allowed value and how zero and negative numbers are
handled.
It is of course true that some of these values will have the potential to
destroy system performance or integrity, and that should be mentioned in the
update to documentation.
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