Add concurrent execs in stress tests

Signed-off-by: Michael Crosby <crosbymichael@gmail.com>

cmd/containerd-stress/exec_worker.go

@@ -18,6 +18,7 @@ package main
 
 import (
 	"context"
+	"fmt"
 	"strings"
 	"syscall"
 	"time"
@@ -38,8 +39,9 @@ func (w *execWorker) exec(ctx, tctx context.Context) {
 		w.wg.Done()
 		logrus.Infof("worker %d finished", w.id)
 	}()
-	c, err := w.client.NewContainer(ctx, "exec-container",
-		containerd.WithNewSnapshot("exec-container", w.image),
+	id := fmt.Sprintf("exec-container-%d", w.id)
+	c, err := w.client.NewContainer(ctx, id,
+		containerd.WithNewSnapshot(id, w.image),
 		containerd.WithNewSpec(oci.WithImageConfig(w.image), oci.WithUsername("games"), oci.WithProcessArgs("sleep", "30d")),
 	)
 	if err != nil {

cmd/containerd-stress/main.go

@@ -257,17 +257,19 @@ func test(c config) error {
 	}
 	var exec *execWorker
 	if c.Exec {
-		wg.Add(1)
-		exec = &execWorker{
-			worker: worker{
-				id:     c.Concurrency,
-				wg:     &wg,
-				image:  image,
-				client: client,
-				commit: v.Revision,
-			},
+		for i := c.Concurrency; i < c.Concurrency+c.Concurrency; i++ {
+			wg.Add(1)
+			exec = &execWorker{
+				worker: worker{
+					id:     i,
+					wg:     &wg,
+					image:  image,
+					client: client,
+					commit: v.Revision,
+				},
+			}
+			go exec.exec(ctx, tctx)
 		}
-		go exec.exec(ctx, tctx)
 	}
 
 	// start the timer and run the worker