Hi there, I've spent time implementing the solr prometheus exporter into our Solr environment. During this, I did come across an issue where when I was getting the core level metris, I was getting exceptions.
Digging into this further, I realised it's actually on the Solr side of this, in particular, the metrics that come from the following group within each core; SEARCHER.* An example of the output I was getting; { "responseHeader":{ "status":500, "QTime":44}, "error":{ "msg":"this IndexReader is closed", "trace":"org.apache.lucene.store.AlreadyClosedException: this IndexReader is closed\n\tat org.apache.lucene.index.IndexReader.ensureOpen(IndexReader.java:257)\n\tat org.apache.lucene.index.StandardDirectoryReader.getVersion(StandardDirectoryReader.java:339)\n\tat org.apache.lucene.index.FilterDirectoryReader.getVersion(FilterDirectoryReader.java:127)\n\tat org.apache.lucene.index.FilterDirectoryReader.getVersion(FilterDirectoryReader.java:127)\n\tat org.apache.solr.search.SolrIndexSearcher.lambda$initializeMetrics$13(SolrIndexSearcher.java:2268) I changed my metric calls to include "®ex=^(?!SEARCHER).*" and the results were coming through *(minus the SEARCHER metrics)*. This was enough to unblock me from getting the rest of the metrics, however, I want to revisit this and see what I can do, as from my point of view, this is a bug within Solr, because it breaks the entire metrics API *(for example, if you just hit /solr/admin/metrics and the IndexReader is Closed, it'll return this message and 0 metrics will be collected/displayed)*. My problem is, I'm not entirely sure how to replica this error? and was hoping I could find some guidance. I saw that the file " org/apache/solr/search/SolrIndexSearcher.java" has the metrics in them, but got a bit lost from first glance. If anyone has any information that could help me; 1. Replicate the issue 2. Explain what exactly does it mean when IndexReader is closed I would be really grateful, Kind Regards, Richard Goodman