Client was running imports using INFILE and errors started popping up like the following:

Error loading canonical_event data file: Internal error: CAL0001: dmlprocessor.cpp PackageHandler::run() package type 3 /home/jenkins/workspace/MariaDBE-Custom-RPM/label/rhel-7/padding_for_CPACK_RPM_BUILD_SOURCE_DIRS_PREFIX_ON_ES_BACKUP_DEBUGSOURCE/Error loading canonical_event data file: 1815 (HY000):
Error loading canonical_event data file: 1815 (HY000): Internal error: CAL0001: Insert Failed: IDB-2009: Unable to perform the batch insert operation because DMLProc batchinsert with PID 7069 is currently holding the table lock for session 28207.
Error loading canonical_event data file: 1815 (HY000): Internal error: IDB-2004: Cannot connect to ExeMgr.

They were running single threaded loads and should not have been trying to load to the same table more than once. Report logs attached.