database/sql: goroutine leak detection made difficult with sql.DB.Close() #50616

MichaelSnowden · 2022-01-14T20:27:19Z

We start a goroutine for connectionOpener like this:

Line 794 in 4f0c32d

go db.connectionOpener(ctx)

And then it terminates when the context is cancelled:

Lines 1224 to 1233 in 4f0c32d

    
           func (db *DB) connectionOpener(ctx context.Context) { 
        
           	for { 
        
           		select { 
        
           		case <-ctx.Done(): 
        
           			return 
        
           		case <-db.openerCh: 
        
           			db.openNewConnection(ctx) 
        
           		} 
        
           	} 
        
           }

Which happens here:

go/src/database/sql/sql.go

Line 910 in 4f0c32d

db.stop()

The Close() method then returns after some additional cleanup. Since we don't wait for the actual goroutine to close, after Close() happens, there could still be a goroutine running.

I think we should add something like this to the OpenDB method:

go func() {
  defer db.openerRoutine.Done()
  db.connectionOpener(ctx)
}

and then add this to the Close() method:

db.stop()
db.openerRoutine.Wait()

This would make it easier to use things like goleak with this library. Currently, I have to workaround it somehow, e.g. with a sleep or an ignore.

The text was updated successfully, but these errors were encountered:

seankhliao changed the title ~~goroutine leak detection made difficult with sql.DB.Close()~~ database/sql: goroutine leak detection made difficult with sql.DB.Close() Jan 16, 2022

seankhliao added the NeedsInvestigation Someone must examine and confirm this is a valid issue and not a duplicate of an existing one. label Jan 16, 2022

seankhliao added this to the Unplanned milestone Aug 20, 2022

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

database/sql: goroutine leak detection made difficult with sql.DB.Close() #50616

database/sql: goroutine leak detection made difficult with sql.DB.Close() #50616

MichaelSnowden commented Jan 14, 2022 •

edited

database/sql: goroutine leak detection made difficult with sql.DB.Close() #50616

database/sql: goroutine leak detection made difficult with sql.DB.Close() #50616

Comments

MichaelSnowden commented Jan 14, 2022 • edited

MichaelSnowden commented Jan 14, 2022 •

edited