Hello (apologies for cross-posting), While working on SOLR-12743, using 7.6 on two nodes and 7.2.1 on the remaining four, we stumbled upon a situation where the 7.6 nodes quickly succumb when a 'Query-of-Death' is issued, 7.2.1 up to 7.5 are all unaffected (tested and confirmed).
Following Smiley's suggestion i used Eclipse MAT to find the problem in the heap dump i obtained, this fantastic tool revealed within minutes that a query thread ate 65 % of all resources, in the class variables i could find the the query, and reproduce the problem. The problematic query is 'dubbele dijk/rijke dijkproject in het dijktracé eemshaven-delfzijl', on 7.6 this input produces a 40+ MB toString() output in edismax' newFieldQuery. If the node survives it takes 2+ seconds for the query to run (150 ms otherwise). If i disable all query time SynonymGraphFilters it still takes a second and produces just a 9 MB toString() for the query. I could not find anything like this in Jira. I did think of LUCENE-8479 and LUCENE-8531 but they were about graphs, this problem looked related though. I think i tracked it further down to LUCENE-8589 or SOLR-12243. When i leave Solr's edismax' pf parameter empty, everything runs fast. When all fields are configured for pf, the node dies. I am now unsure whether this is a Solr or a Lucene issue. Please let me know. Many thanks, Markus ps. in Solr i even got an 'Impossible Exception', my first!
