为何Docker环境下Redis性能比原生部署时更低？

我在1核CPU、1GB内存、Ubuntu 22.04系统的VPS上完成了Redis性能对比测试，结果显示Docker部署的Redis性能均低于原生部署，以下是测试细节及可能的影响因素：

测试场景及结果 #

1. 宿主机原生Redis（性能最优） #

部署与测试命令：

sudo apt-get update
sudo apt-get install redis # redis_version:6.0.16
redis-benchmark -q -n 100000 

测试结果：

PING_INLINE: 23004.37 requests per second
PING_BULK: 21915.41 requests per second
SET: 23792.53 requests per second
GET: 22867.60 requests per second
INCR: 23894.86 requests per second
LPUSH: 25252.53 requests per second
RPUSH: 24551.93 requests per second
LPOP: 24414.06 requests per second
RPOP: 24307.24 requests per second
SADD: 23512.82 requests per second
HSET: 24746.35 requests per second
SPOP: 22758.31 requests per second
ZADD: 23969.32 requests per second
ZPOPMIN: 22701.47 requests per second
LPUSH (needed to benchmark LRANGE): 24113.82 requests per second
LRANGE_100 (first 100 elements): 17531.56 requests per second
LRANGE_300 (first 300 elements): 7954.18 requests per second
LRANGE_500 (first 450 elements): 6106.12 requests per second
LRANGE_600 (first 600 elements): 5296.89 requests per second
MSET (10 keys): 30012.00 requests per second

2. Docker中Redis（容器外测试，性能最差） #

部署与测试命令：

docker pull redis:6.0.17
docker run --name redis -p 6378:6379 -d redis:6.0.17
redis-benchmark -q -n 100000 -p 6378

测试结果：

PING_INLINE: 7548.31 requests per second
PING_BULK: 7623.69 requests per second
SET: 7474.96 requests per second
GET: 7474.96 requests per second
INCR: 7488.95 requests per second
LPUSH: 7443.25 requests per second
RPUSH: 7487.27 requests per second
LPOP: 7401.92 requests per second
RPOP: 7163.84 requests per second
SADD: 7252.16 requests per second
HSET: 7192.17 requests per second
SPOP: 7217.61 requests per second
ZADD: 7331.38 requests per second
ZPOPMIN: 7597.63 requests per second
LPUSH (needed to benchmark LRANGE): 7392.62 requests per second
LRANGE_100 (first 100 elements): 6248.05 requests per second
LRANGE_300 (first 300 elements): 6377.55 requests per second
LRANGE_500 (first 450 elements): 5748.45 requests per second
LRANGE_600 (first 600 elements): 4578.75 requests per second
MSET (10 keys): 6895.60 requests per second

3. 容器内运行测试（略慢于宿主机） #

测试命令：

docker exec -it redis sh
redis-benchmark -q -n 100000

测试结果：

PING_INLINE: 22416.50 requests per second
PING_BULK: 21654.40 requests per second
SET: 23413.72 requests per second
GET: 22351.36 requests per second
INCR: 22784.23 requests per second
LPUSH: 24467.83 requests per second
RPUSH: 23651.84 requests per second
LPOP: 23781.21 requests per second
RPOP: 23691.07 requests per second
SADD: 22747.95 requests per second
HSET: 24301.34 requests per second
SPOP: 22172.95 requests per second
ZADD: 24301.34 requests per second
ZPOPMIN: 22578.46 requests per second
LPUSH (needed to benchmark LRANGE): 24177.95 requests per second
LRANGE_100 (first 100 elements): 13817.88 requests per second
LRANGE_300 (first 300 elements): 7212.93 requests per second
LRANGE_500 (first 450 elements): 5898.31 requests per second
LRANGE_600 (first 600 elements): 4890.45 requests per second
MSET (10 keys): 29154.52 requests per second

4. Docker Compose跨容器测试（性能中等） #

配置文件：

# Dockerfile
FROM redis:6.0.17
CMD redis-benchmark -q -n 100000 -h redis

# docker-compose.yml
version: "3.9"
services:
  web:
    build: .
  redis:
    image: "redis:6.0.17"

测试结果：

PING_INLINE: 16173.38 requests per second, p50=1.495 msec
PING_MBULK: 15172.20 requests per second, p50=1.503 msec
SET: 15989.77 requests per second, p50=1.503 msec
GET: 15701.05 requests per second, p50=1.511 msec
INCR: 16121.23 requests per second, p50=1.487 msec
LPUSH: 16428.46 requests per second, p50=1.495 msec
RPUSH: 14630.58 requests per second, p50=1.639 msec
LPOP: 15542.43 requests per second, p50=1.567 msec
RPOP: 15518.31 requests per second, p50=1.551 msec
SADD: 14900.91 requests per second, p50=1.567 msec
HSET: 15176.81 requests per second, p50=1.575 msec
SPOP: 14918.69 requests per second, p50=1.583 msec
ZADD: 15855.40 requests per second, p50=1.543 msec
ZPOPMIN: 15248.55 requests per second, p50=1.551 msec
LPUSH (needed to benchmark LRANGE): 16466.33 requests per second, p50=1.495 msec
LRANGE_100 (first 100 elements): 10330.58 requests per second, p50=2.423 msec
LRANGE_300 (first 300 elements): 5361.07 requests per second, p50=4.671 msec
LRANGE_500 (first 500 elements): 3863.99 requests per second, p50=6.191 msec
LRANGE_600 (first 600 elements): 3718.99 requests per second, p50=6.559 msec
MSET (10 keys): 20618.56 requests per second, p50=1.415 msec

可能的性能影响因素 #

从测试数据的差异可以看出，不同部署方式的性能差距主要来自以下几个方面：

• 网络层开销：这是最显著的因素。容器外通过端口映射（-p）访问Redis时，数据包需要经过Docker的桥接网络、NAT转换，相比原生的本地套接字或直连TCP，额外的网络转发带来了巨大的性能损耗。而容器内测试使用localhost访问，网络开销极小，性能接近原生；Docker Compose的跨容器测试使用自定义桥接网络，NAT开销比宿主机端口映射小，但仍存在一定的转发损耗。

• 容器隔离机制的微小开销：即使是容器内测试，性能略低于原生，这是因为Docker通过cgroups进行资源限制、namespace实现隔离，这些机制会带来非常轻微的CPU调度、内存管理开销，在资源紧张的1核1G VPS上会被放大。

• Redis版本差异：原生Redis是6.0.16，Docker使用的是6.0.17，虽然版本差异极小，但不排除小版本间的细微性能差别。

• 资源限制：Docker默认会限制容器的资源使用，如果没有显式配置CPU、内存的限制参数，容器可能无法完全利用宿主机的资源，在1核CPU的环境下，这种资源竞争会导致性能下降。

内容的提问来源于stack exchange，提问作者Dmitry