open 1 conn at a time

cmd/pg-pulse/main.go

@@ -7,6 +7,7 @@ import (
 	"fmt"
 	"log"
 	"os"
+	"sync"
 	"time"
 
 	"gitea.bel.blue/bel/with"
@@ -24,10 +25,28 @@ func run(ctx context.Context) error {
 	fs := flag.NewFlagSet(os.Args[0], flag.ContinueOnError)
 	c := fs.String("c", "postgresql://pulsegres:pulsegres@localhost:15432", "conn string")
 	d := fs.Duration("d", time.Second, "interval")
+	p := fs.Int("p", 1, "concurrent goroutines")
 	if err := fs.Parse(os.Args[1:]); err != nil {
 		panic(err)
 	}
 
+	for i := 0; i < *p-1; i++ {
+		func() {
+			connected := &sync.WaitGroup{}
+			connected.Add(1)
+			go with.PSQL(ctx, *c, func(pg *sql.DB) error {
+				connected.Done()
+				with.GoEvery(ctx, *d, func() {
+					if _, err := pg.ExecContext(ctx, `SELECT 1`); err != nil {
+						log.Println("!", err)
+					}
+				})
+				return ctx.Err()
+			})
+			connected.Wait()
+		}()
+	}
+
 	return with.PSQL(ctx, *c, func(pg *sql.DB) error {
 		log.Println("staging...")
 		if _, err := pg.ExecContext(ctx, `