Redis Connections

Redis Connections

Client-side guidance for talking to Redis efficiently: how to share connections, how to batch commands, which commands not to call in production, when to turn on client-side caching, and how to set timeouts that fail fast without breaking healthy traffic.

When to apply

• Creating or reviewing a Redis client setup (redis-py, Jedis, Lettuce, go-redis, NRedisStack).
• Making many small Redis calls and wondering where the latency is going.
• Iterating large keyspaces, sets, hashes, or lists.
• Enabling client-side caching for hot keys.
• Tuning connect / read / write timeouts.

1. Pool or multiplex — never one connection per request

The single biggest mistake in Redis client code is opening a new TCP connection for every operation. Always either:

• Pool — keep N persistent connections that the application leases per call (redis-py ConnectionPool, Jedis JedisPooled, go-redis client).
• Multiplex — share a single connection across all requests (Lettuce, NRedisStack).

| Style | Used by | Note |

|---|---|---|

| Pool | redis-py, Jedis, go-redis | Each lease blocks if pool exhausted; size the pool to your concurrency |

| Multiplex | Lettuce, NRedisStack | Single connection; cannot carry blocking commands like BLPOP |

# redis-py — connection pool
pool = redis.ConnectionPool(host="localhost", port=6379, max_connections=50)
r = redis.Redis(connection_pool=pool)

See references/pooling.md for Python + Java + Lettuce examples.

2. Pipeline bulk work

For N commands that don't depend on each other's results, send them as a single batch with pipelining. One round-trip instead of N.

pipe = redis.pipeline()
for user_id in user_ids:
    pipe.get(f"user:{user_id}")
results = pipe.execute()

Use non-transactional pipelining for performance, and pipeline(transaction=True) only when you actually need atomicity (see redis-core's transactions guidance).

See references/pipelining.md.

3. Avoid commands that scan everything

Anything that walks the whole keyspace (or a whole large container) blocks the server. Use incremental variants instead.

| Don't | Use |

|---|---|

| KEYS pattern | SCAN cursor loop |

| SMEMBERS large_set | SSCAN |

| HGETALL large_hash | HSCAN |

| LRANGE 0 -1 on a huge list | Paginate (LRANGE 0 100) |

cursor = 0
while True:
    cursor, keys = redis.scan(cursor, match="user:*", count=100)
    for key in keys:
        process(key)
    if cursor == 0:
        break

Blocking commands (BLPOP, BRPOP, BLMOVE) are different — they intentionally wait for data and are fine for queue consumers, but always pass a timeout, and don't issue them on a multiplexed connection (Lettuce, NRedisStack).

See references/blocking.md.

4. Client-side caching for hot keys

For data that's read often and written rarely (config, feature flags, sessions on every request), enable RESP3 client-side caching. The client keeps a local copy and the server invalidates it on writes — saving the round trip for hot reads.

client = redis.Redis(
    host="localhost",
    port=6379,
    protocol=3,                                    # RESP3 is required
    cache_config=redis.CacheConfig(max_size=1000),
)

Skip it for write-heavy workloads or data that changes constantly — the invalidation traffic overruns the savings.

See references/client-cache.md.

5. Set explicit timeouts

Defaults vary by client and may be too generous. Pick values that match the *application's* failure model:

r = redis.Redis(
    host="localhost",
    socket_connect_timeout=2.0,   # fail fast on dead nodes
    socket_timeout=5.0,           # tune to expected operation time
    retry_on_timeout=True,
)

Rule of thumb: connect timeout shorter than read/write timeout. Tight timeouts + retry-on-timeout for latency-sensitive paths; longer timeouts for batch jobs.

See references/timeouts.md.

References

• Redis: Connection Pools and Multiplexing
• Redis: Pipelining
• Redis: SCAN
• Redis: Client-side caching
• Redis: Clients