Calcite planner might have a thread-safety issue compiling in parallel

After about 6 minutes trying to plan a query, the HiveServer2 was killed to restore functionality to a test run.

The HEP planner is stuck on a TopologicalOrder traversal and there were no queries being fed into the HiveServer2 after it got stuck.

TPC-DS query13 was the query in question, at 4 way parallel, which triggered the issue.