@@ -584,12 +584,14 @@ partition_table_concurrently(PG_FUNCTION_ARGS)
584584#define tostr (str ) ( #str )/* convert function's name to literal */
585585
586586Oid relid = PG_GETARG_OID (0 );
587- int empty_slot_idx = -1 ;
587+ int empty_slot_idx = -1 ;/* do we have a slot for BGWorker? */
588588int i ;
589589
590590/* Check if relation is a partitioned table */
591591shout_if_prel_is_invalid (relid ,
592+ /* We also lock the parent relation */
592593get_pathman_relation_info_after_lock (relid , true),
594+ /* Partitioning type does not matter here */
593595PT_INDIFFERENT );
594596
595597/*
@@ -601,30 +603,38 @@ partition_table_concurrently(PG_FUNCTION_ARGS)
601603ConcurrentPartSlot * cur_slot = & concurrent_part_slots [i ];
602604bool keep_this_lock = false;
603605
606+ /* Lock current slot */
604607SpinLockAcquire (& cur_slot -> mutex );
605608
606- /* Should we take this slot into account? */
609+ /* Should we take this slot into account?(it should be FREE) */
607610if (empty_slot_idx < 0 && cur_slot -> worker_status == CPS_FREE )
608611{
609- empty_slot_idx = i ;
610- keep_this_lock = true;
612+ empty_slot_idx = i ;/* yes, remember this slot */
613+ keep_this_lock = true;/* also don't unlock it */
611614}
612615
616+ /* Oops, looks like we already have BGWorker for this table */
613617if (cur_slot -> relid == relid &&
614618cur_slot -> dbid == MyDatabaseId )
615619{
616- if (empty_slot_idx >=0 )
617- SpinLockRelease (& cur_slot -> mutex );
620+ /* Unlock current slot */
621+ SpinLockRelease (& cur_slot -> mutex );
622+
623+ /* Release borrowed slot for new BGWorker too */
624+ if (empty_slot_idx >=0 && empty_slot_idx != i )
625+ SpinLockRelease (& concurrent_part_slots [empty_slot_idx ].mutex );
618626
619627elog (ERROR ,
620628"Table \"%s\" is already being partitioned" ,
621629get_rel_name (relid ));
622630}
623631
632+ /* Normally we don't want to keep it */
624633if (!keep_this_lock )
625634SpinLockRelease (& cur_slot -> mutex );
626635}
627636
637+ /* Looks like we could not find an empty slot */
628638if (empty_slot_idx < 0 )
629639elog (ERROR ,"No empty worker slots found" );
630640else
@@ -634,6 +644,7 @@ partition_table_concurrently(PG_FUNCTION_ARGS)
634644GetAuthenticatedUserId (),CPS_WORKING ,
635645MyDatabaseId ,relid ,1000 ,1.0 );
636646
647+ /* Now we can safely unlock slot for new BGWorker */
637648SpinLockRelease (& concurrent_part_slots [empty_slot_idx ].mutex );
638649}
639650