Solr Upgrade to 9.8.1 – Performance Observations and multiThreaded Parameter

[Sarita <sa...@gmail.com>]

Hi Team,

We recently upgraded Solr from version 9.3 to 9.8.1 and have not observed
any performance degradation with the following configurations in place:

Schema changes were applied to maintain backward compatibility with version
9.3, following the official upgrade guidelines
https://solr.apache.org/guide/solr/latest/upgrade-notes/solr-upgrade-notes.html
.

*We retained the default settings introduced in recent versions:*
DocValues enabled by default in Solr 9.7
Uninvertible fields disabled in Solr 9.8
We are using the SolrJ client version 9.8.

Additionally, we made the following performance-related changes:
*On the server side:*
Enabled *-Dsolr.segment.threads=true* in the startup script.
Set* indexSearcherExecutorThreads = -1* in the Solr configuration.

*On the client side:*
Set the *multiThreaded = true* parameter. We noticed significant
performance degradation when this was not enabled.

We would like to check if there are any plans to deprecate or remove the
experimental multiThreaded parameter in future releases, as it currently
plays a critical role in maintaining our performance benchmarks.

Please keep us informed of any relevant updates or changes.

Thanks,
Sarita

Re: Solr Upgrade to 9.8.1 – Performance Observations and multiThreaded Parameter

[Houston Putman <ho...@gmail.com>]

Hello Sarita,

This is really a question that is best for the user list. But as far as
this question is concerned:

We would like to check if there are any plans to deprecate or remove the
> experimental multiThreaded parameter in future releases
>

No,  and the only reason "indexSearcherExecutorThreads" was set to 0 as a
default was for users that wanted to use "multiThreaded = false" which is
the default. Having "indexSearcherExecutorThreads != 0" does not currently
work well when "multiThreaded = false".

- Houston

On Wed, Apr 16, 2025 at 4:49 AM Sarita <sa...@gmail.com> wrote:

> Hi Team,
>
> We recently upgraded Solr from version 9.3 to 9.8.1 and have not observed
> any performance degradation with the following configurations in place:
>
> Schema changes were applied to maintain backward compatibility with version
> 9.3, following the official upgrade guidelines
>
> https://solr.apache.org/guide/solr/latest/upgrade-notes/solr-upgrade-notes.html
> .
>
> *We retained the default settings introduced in recent versions:*
> DocValues enabled by default in Solr 9.7
> Uninvertible fields disabled in Solr 9.8
> We are using the SolrJ client version 9.8.
>
> Additionally, we made the following performance-related changes:
> *On the server side:*
> Enabled *-Dsolr.segment.threads=true* in the startup script.
> Set* indexSearcherExecutorThreads = -1* in the Solr configuration.
>
> *On the client side:*
> Set the *multiThreaded = true* parameter. We noticed significant
> performance degradation when this was not enabled.
>
> We would like to check if there are any plans to deprecate or remove the
> experimental multiThreaded parameter in future releases, as it currently
> plays a critical role in maintaining our performance benchmarks.
>
> Please keep us informed of any relevant updates or changes.
>
> Thanks,
> Sarita
>