[SOLR-17454] ERROR message in logs with multithreaded searches

• Type: Bug
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 9.7
• Fix Version/s: 9.8
• Component/s: search
• Labels: docs error log-level multithreaded pull-request-available

Environment

Solr 9.7.0

Ubuntu 22.04 LTS

• Assignee: Unassigned
• Reporter: Andrew Hankinson
• Created: 16/Sep/24 09:06
• Updated: 27/Sep/24 20:19
• Resolved: 27/Sep/24 20:19

Description

I sent a message to the Users mailing list about this, but received no response. However, I think it is still a problem. 

When searching with 9.7.0 and enabled multithreaded search, I now get an ERROR message in my logs: 

2024-09-16 08:32:05.795 ERROR (qtp1756573246-34-null-1) [c: s: r: x:core_name t:null-1] o.a.s.s.MultiThreadedSearcher raw read max=5922019 

The max number is the total number of documents in the core.

I've tracked it down to this part of the code:

https://github.com/apache/solr/blob/5bc7c1618e05b35bd0fa8471ae09329357a82036/solr/core/src/java/org/apache/solr/search/MultiThreadedSearcher.java#L86-L91

I'm not entirely convinced that an ERROR level message is necessary here? 

• The query seems to still function;
• Once the error condition is logged, the code seems to create a new doc set and continues;
• The documentation doesn't suggest anything for how to avoid this? I'm not sure why "needDocSet" is true here, and how it can be anything otherwise?

Surely an "info" or "warn" log message is more appropriate for these cases? Unless it really is an error condition, but then the docs should be updated to mention what could be done to avoid the error?

Issue Links

• links to: GitHub Pull Request #2720