diff --git a/go.mod b/go.mod
index 891237c..acc1771 100644
--- a/go.mod
+++ b/go.mod
@@ -11,6 +11,7 @@ require (
 	github.com/mcuadros/go-defaults v1.2.0
 	github.com/mitchellh/mapstructure v1.5.0
 	google.golang.org/grpc v1.67.1
+	google.golang.org/protobuf v1.35.1
 )
 
 require (
@@ -41,7 +42,6 @@ require (
 	golang.org/x/sys v0.26.0 // indirect
 	golang.org/x/text v0.19.0 // indirect
 	google.golang.org/genproto/googleapis/rpc v0.0.0-20241021214115-324edc3d5d38 // indirect
-	google.golang.org/protobuf v1.35.1 // indirect
 	gopkg.in/warnings.v0 v0.1.2 // indirect
 	gopkg.in/yaml.v2 v2.4.0 // indirect
 )
diff --git a/internal/executor/sandbox/executor.go b/internal/executor/sandbox/executor.go
index 40afa00..01311ee 100644
--- a/internal/executor/sandbox/executor.go
+++ b/internal/executor/sandbox/executor.go
@@ -7,6 +7,7 @@ import (
 
 	"github.com/criyle/go-judge/pb"
 	"github.com/joint-online-judge/JOJ3/internal/stage"
+	"google.golang.org/protobuf/proto"
 )
 
 type Sandbox struct {
@@ -37,7 +38,24 @@ func (e *Sandbox) Run(cmds []stage.Cmd) ([]stage.ExecutorResult, error) {
 		}
 	}
 	pbCmds := convertPBCmd(cmds)
-	slog.Debug("sandbox execute", "protobuf cmds", pbCmds)
+	for i, pbCmd := range pbCmds {
+		slog.Debug(
+			"sandbox execute",
+			"index", i,
+			"protobuf cmd size", proto.Size(pbCmd),
+			"protobuf cmd stdin size", proto.Size(pbCmd.Files[0]),
+			"protobuf cmd stdout size", proto.Size(pbCmd.Files[1]),
+			"protobuf cmd stderr size", proto.Size(pbCmd.Files[2]),
+		)
+		for k, v := range pbCmd.CopyIn {
+			slog.Debug(
+				"sandbox execute",
+				"index", i,
+				"CopyIn filename", k,
+				"protobuf file size", proto.Size(v),
+			)
+		}
+	}
 	pbReq := &pb.Request{Cmd: pbCmds}
 	pbRet, err := e.execClient.Exec(context.TODO(), pbReq)
 	if err != nil {