Comment 4 for bug 1853071

Finally since i'm not an SQL expert, here is output of SHOW ENGINE INNODB STATUS': http://paste.openstack.org/show/786369/

There are a bunch of neutron transactions active for 1397 seconds. Some for 96 seconds. And a bunch that are "not started".

Two of them indicate they have been waiting on a lock like so:

---TRANSACTION 57170620, ACTIVE 1397 sec
MySQL thread id 169, OS thread handle 0x7fa3375f5700, query id 36577 localhost 127.0.0.1 neutron
Trx read view will not see trx with id >= 57170621, sees < 57170585
---TRANSACTION 57170619, ACTIVE 1397 sec starting index read
mysql tables in use 1, locked 1
LOCK WAIT 2 lock struct(s), heap size 360, 1 row lock(s)
MySQL thread id 168, OS thread handle 0x7fa337637700, query id 123513 localhost 127.0.0.1 neutron updating
UPDATE agents SET heartbeat_timestamp='2019-11-19 20:54:45.480969' WHERE agents.id = '1d7c5726-a336-4156-ace5-952d5363ad50'
Trx read view will not see trx with id >= 57170620, sees < 57170585
------- TRX HAS BEEN WAITING 17 SEC FOR THIS LOCK TO BE GRANTED:
RECORD LOCKS space id 204 page no 3 n bits 88 index `PRIMARY` of table `neutron`.`agents` trx id 57170619 lock_mode X locks rec but not gap waiting
Record lock, heap no 6 PHYSICAL RECORD: n_fields 16; compact format; info bits 0
 0: len 30; hex 31643763353732362d613333362d343135362d616365352d393532643533; asc 1d7c5726-a336-4156-ace5-952d53; (total 36 bytes);
 1: len 6; hex 000003685a9e; asc hZ ;;
 2: len 7; hex 560000026d1233; asc V m 3;;
 3: len 14; hex 4d65746164617461206167656e74; asc Metadata agent;;
 4: len 22; hex 6e657574726f6e2d6d657461646174612d6167656e74; asc neutron-metadata-agent;;
 5: len 3; hex 4e2f41; asc N/A;;
 6: len 30; hex 64333062303339302d323066642d343366652d393566382d313037396330; asc d30b0390-20fd-43fe-95f8-1079c0; (total 36 bytes);
 7: len 1; hex 81; asc ;;
 8: len 5; hex 99a34f6033; asc O`3;;
 9: len 5; hex 99a41b7ab4; asc z ;;
 10: len 5; hex 99a4a74dad; asc M ;;
 11: SQL NULL;
 12: len 30; hex 7b226c6f675f6167656e745f68656172746265617473223a2066616c7365; asc {"log_agent_heartbeats": false; (total 158 bytes);
 13: len 4; hex 80000000; asc ;;
 14: SQL NULL;
 15: SQL NULL;