diff --git a/README.md b/README.md
index 08a151e..1a0e460 100644
--- a/README.md
+++ b/README.md
@@ -138,7 +138,7 @@ res, err := rdb.Do(ctx, "set", "key", "value").Result()
 
 go-redis will start a redis-server and run the test cases.
 
-The paths of redis-server bin file and redis config file are definded in `main_test.go`:
+The paths of redis-server bin file and redis config file are defined in `main_test.go`:
 
 ```
 var (
diff --git a/error.go b/error.go
index 2ed5dc6..ad9e173 100644
--- a/error.go
+++ b/error.go
@@ -10,6 +10,7 @@ import (
 	"github.com/go-redis/redis/v8/internal/proto"
 )
 
+// ErrClosed performs any operation on the closed client will return this error.
 var ErrClosed = pool.ErrClosed
 
 type Error interface {
diff --git a/extra/redisotel/go.mod b/extra/redisotel/go.mod
index f514a06..9e60138 100644
--- a/extra/redisotel/go.mod
+++ b/extra/redisotel/go.mod
@@ -9,6 +9,6 @@ replace github.com/go-redis/redis/extra/rediscmd/v8 => ../rediscmd
 require (
 	github.com/go-redis/redis/extra/rediscmd/v8 v8.8.2
 	github.com/go-redis/redis/v8 v8.8.2
-	go.opentelemetry.io/otel v0.19.0
-	go.opentelemetry.io/otel/trace v0.19.0
+	go.opentelemetry.io/otel v0.20.0
+	go.opentelemetry.io/otel/trace v0.20.0
 )
diff --git a/extra/redisotel/go.sum b/extra/redisotel/go.sum
index 182608e..1aa1088 100644
--- a/extra/redisotel/go.sum
+++ b/extra/redisotel/go.sum
@@ -39,12 +39,19 @@ github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/
 github.com/yuin/goldmark v1.2.1/go.mod h1:3hX8gzYuyVAZsxl0MRgGTJEmQBFcNTphYh9decYSb74=
 go.opentelemetry.io/otel v0.19.0 h1:Lenfy7QHRXPZVsw/12CWpxX6d/JkrX8wrx2vO8G80Ng=
 go.opentelemetry.io/otel v0.19.0/go.mod h1:j9bF567N9EfomkSidSfmMwIwIBuP37AMAIzVW85OxSg=
+go.opentelemetry.io/otel v0.20.0 h1:eaP0Fqu7SXHwvjiqDq83zImeehOHX8doTvU9AwXON8g=
+go.opentelemetry.io/otel v0.20.0/go.mod h1:Y3ugLH2oa81t5QO+Lty+zXf8zC9L26ax4Nzoxm/dooo=
 go.opentelemetry.io/otel/metric v0.19.0 h1:dtZ1Ju44gkJkYvo+3qGqVXmf88tc+a42edOywypengg=
 go.opentelemetry.io/otel/metric v0.19.0/go.mod h1:8f9fglJPRnXuskQmKpnad31lcLJ2VmNNqIsx/uIwBSc=
+go.opentelemetry.io/otel/metric v0.20.0 h1:4kzhXFP+btKm4jwxpjIqjs41A7MakRFUS86bqLHTIw8=
+go.opentelemetry.io/otel/metric v0.20.0/go.mod h1:598I5tYlH1vzBjn+BTuhzTCSb/9debfNp6R3s7Pr1eU=
 go.opentelemetry.io/otel/oteltest v0.19.0 h1:YVfA0ByROYqTwOxqHVZYZExzEpfZor+MU1rU+ip2v9Q=
 go.opentelemetry.io/otel/oteltest v0.19.0/go.mod h1:tI4yxwh8U21v7JD6R3BcA/2+RBoTKFexE/PJ/nSO7IA=
+go.opentelemetry.io/otel/oteltest v0.20.0/go.mod h1:L7bgKf9ZB7qCwT9Up7i9/pn0PWIa9FqQ2IQ8LoxiGnw=
 go.opentelemetry.io/otel/trace v0.19.0 h1:1ucYlenXIDA1OlHVLDZKX0ObXV5RLaq06DtUKz5e5zc=
 go.opentelemetry.io/otel/trace v0.19.0/go.mod h1:4IXiNextNOpPnRlI4ryK69mn5iC84bjBWZQA5DXz/qg=
+go.opentelemetry.io/otel/trace v0.20.0 h1:1DL6EXUdcg95gukhuRRvLDO/4X5THh/5dIV52lqtnbw=
+go.opentelemetry.io/otel/trace v0.20.0/go.mod h1:6GjCW8zgDjwGHGa6GkyeB8+/5vjT16gUEi0Nf1iBdgw=
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
 golang.org/x/crypto v0.0.0-20191011191535-87dc89f01550/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
 golang.org/x/crypto v0.0.0-20200622213623-75b288015ac9/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
diff --git a/go.mod b/go.mod
index 1d3dfe1..4fb27a8 100644
--- a/go.mod
+++ b/go.mod
@@ -7,7 +7,7 @@ require (
 	github.com/dgryski/go-rendezvous v0.0.0-20200823014737-9f7001d12a5f
 	github.com/onsi/ginkgo v1.15.0
 	github.com/onsi/gomega v1.10.5
-	go.opentelemetry.io/otel v0.19.0
-	go.opentelemetry.io/otel/metric v0.19.0
-	go.opentelemetry.io/otel/trace v0.19.0
+	go.opentelemetry.io/otel v0.20.0
+	go.opentelemetry.io/otel/metric v0.20.0
+	go.opentelemetry.io/otel/trace v0.20.0
 )
diff --git a/go.sum b/go.sum
index 182608e..b830936 100644
--- a/go.sum
+++ b/go.sum
@@ -37,14 +37,14 @@ github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+
 github.com/stretchr/testify v1.7.0 h1:nwc3DEeHmmLAfoZucVR881uASk0Mfjw8xYJ99tb5CcY=
 github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
 github.com/yuin/goldmark v1.2.1/go.mod h1:3hX8gzYuyVAZsxl0MRgGTJEmQBFcNTphYh9decYSb74=
-go.opentelemetry.io/otel v0.19.0 h1:Lenfy7QHRXPZVsw/12CWpxX6d/JkrX8wrx2vO8G80Ng=
-go.opentelemetry.io/otel v0.19.0/go.mod h1:j9bF567N9EfomkSidSfmMwIwIBuP37AMAIzVW85OxSg=
-go.opentelemetry.io/otel/metric v0.19.0 h1:dtZ1Ju44gkJkYvo+3qGqVXmf88tc+a42edOywypengg=
-go.opentelemetry.io/otel/metric v0.19.0/go.mod h1:8f9fglJPRnXuskQmKpnad31lcLJ2VmNNqIsx/uIwBSc=
-go.opentelemetry.io/otel/oteltest v0.19.0 h1:YVfA0ByROYqTwOxqHVZYZExzEpfZor+MU1rU+ip2v9Q=
-go.opentelemetry.io/otel/oteltest v0.19.0/go.mod h1:tI4yxwh8U21v7JD6R3BcA/2+RBoTKFexE/PJ/nSO7IA=
-go.opentelemetry.io/otel/trace v0.19.0 h1:1ucYlenXIDA1OlHVLDZKX0ObXV5RLaq06DtUKz5e5zc=
-go.opentelemetry.io/otel/trace v0.19.0/go.mod h1:4IXiNextNOpPnRlI4ryK69mn5iC84bjBWZQA5DXz/qg=
+go.opentelemetry.io/otel v0.20.0 h1:eaP0Fqu7SXHwvjiqDq83zImeehOHX8doTvU9AwXON8g=
+go.opentelemetry.io/otel v0.20.0/go.mod h1:Y3ugLH2oa81t5QO+Lty+zXf8zC9L26ax4Nzoxm/dooo=
+go.opentelemetry.io/otel/metric v0.20.0 h1:4kzhXFP+btKm4jwxpjIqjs41A7MakRFUS86bqLHTIw8=
+go.opentelemetry.io/otel/metric v0.20.0/go.mod h1:598I5tYlH1vzBjn+BTuhzTCSb/9debfNp6R3s7Pr1eU=
+go.opentelemetry.io/otel/oteltest v0.20.0 h1:HiITxCawalo5vQzdHfKeZurV8x7ljcqAgiWzF6Vaeaw=
+go.opentelemetry.io/otel/oteltest v0.20.0/go.mod h1:L7bgKf9ZB7qCwT9Up7i9/pn0PWIa9FqQ2IQ8LoxiGnw=
+go.opentelemetry.io/otel/trace v0.20.0 h1:1DL6EXUdcg95gukhuRRvLDO/4X5THh/5dIV52lqtnbw=
+go.opentelemetry.io/otel/trace v0.20.0/go.mod h1:6GjCW8zgDjwGHGa6GkyeB8+/5vjT16gUEi0Nf1iBdgw=
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
 golang.org/x/crypto v0.0.0-20191011191535-87dc89f01550/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
 golang.org/x/crypto v0.0.0-20200622213623-75b288015ac9/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
diff --git a/internal/hashtag/hashtag.go b/internal/hashtag/hashtag.go
index 2fc74ad..b3a4f21 100644
--- a/internal/hashtag/hashtag.go
+++ b/internal/hashtag/hashtag.go
@@ -60,7 +60,7 @@ func RandomSlot() int {
 	return rand.Intn(slotNumber)
 }
 
-// hashSlot returns a consistent slot number between 0 and 16383
+// Slot returns a consistent slot number between 0 and 16383
 // for any given string key.
 func Slot(key string) int {
 	if key == "" {
diff --git a/internal/log.go b/internal/log.go
index 3810f9e..c8b9213 100644
--- a/internal/log.go
+++ b/internal/log.go
@@ -19,6 +19,8 @@ func (l *logger) Printf(ctx context.Context, format string, v ...interface{}) {
 	_ = l.log.Output(2, fmt.Sprintf(format, v...))
 }
 
+// Logger calls Output to print to the stderr.
+// Arguments are handled in the manner of fmt.Print.
 var Logger Logging = &logger{
 	log: log.New(os.Stderr, "redis: ", log.LstdFlags|log.Lshortfile),
 }
diff --git a/internal/pool/pool.go b/internal/pool/pool.go
index 74fbb37..4d247b3 100644
--- a/internal/pool/pool.go
+++ b/internal/pool/pool.go
@@ -12,7 +12,10 @@ import (
 )
 
 var (
-	ErrClosed      = errors.New("redis: client is closed")
+	// ErrClosed performs any operation on the closed client will return this error.
+	ErrClosed = errors.New("redis: client is closed")
+
+	// ErrPoolTimeout timed out waiting to get a connection from the connection pool.
 	ErrPoolTimeout = errors.New("redis: connection pool timeout")
 )
 
diff --git a/internal/proto/reader.go b/internal/proto/reader.go
index 410e466..415e2d9 100644
--- a/internal/proto/reader.go
+++ b/internal/proto/reader.go
@@ -12,6 +12,7 @@ import (
 	"github.com/go-redis/redis/v8/internal/util"
 )
 
+// redis resp protocol data type.
 const (
 	RespStatus    = '+' // +<string>\r\n
 	RespError     = '-' // -<string>\r\n