So this means Flow opening the explicit transaction is implicitly committing the DBO_TRX transaction, right?

I think this must be one of the wikis where the Flow tables are in the main DB.

Do you have a permalink for the Kibana?

I tried:

https://logstash.wikimedia.org/app/kibana#/dashboard/default?_g=(refreshInterval:(display:Off,pause:!f,value:0),time:(from:now%2Fw,mode:quick,to:now%2Fw))&_a=(filters:!(),options:(darkTheme:!f),panels:!((col:1,id:Dashboards,panelIndex:1,row:1,size_x:12,size_y:1,type:visualization),(col:1,id:Events-Over-Time,panelIndex:2,row:2,size_x:12,size_y:2,type:visualization),(col:1,id:Event-Types,panelIndex:3,row:4,size_x:9,size_y:2,type:visualization),(col:10,id:Event-Level,panelIndex:4,row:4,size_x:3,size_y:2,type:visualization),(col:1,columns:!(type,level,wiki,host,message),id:Default-Events-List,panelIndex:5,row:6,size_x:12,size_y:25,sort:!('@timestamp',desc),type:search)),query:(query_string:(analyze_wildcard:!t,query:'message:%22Flow%5CSubmissionHandler%22%20message:%22Automatic%20transaction%20with%20writes%20in%20progress%22')),title:default,uiState:(P-2:(vis:(legendOpen:!f)),P-3:(vis:(legendOpen:!f)),P-4:(vis:(legendOpen:!f))))

but it is not working for me. It shows a bunch of non-Flow stuff.

Change 301069 had a related patch set uploaded (by Aaron Schulz):
Simplify and cleanup SubmissionHandler transaction

https://gerrit.wikimedia.org/r/301069

Change 301069 merged by jenkins-bot:
Simplify and cleanup SubmissionHandler transaction

https://gerrit.wikimedia.org/r/301069