Summary

Adds ConnMaxLifetimeJitter configuration to distribute connection expiration times and prevent the thundering herd problem when many connections expire simultaneously.

Changes

• Added ConnMaxLifetimeJitter time.Duration to all client options (Client, Sentinel, Ring, Universal, Cluster)
• Implemented calcConnExpiresAt() method that applies random jitter in range [-jitter, +jitter]
• Added URL parameter support: conn_max_lifetime_jitter
• Jitter is automatically capped at ConnMaxLifetime value

Usage

// Programmatic
client := redis.NewClient(&redis.Options{
    Addr:                  "localhost:6379",
    ConnMaxLifetime:       1 * time.Hour,
    ConnMaxLifetimeJitter: 5 * time.Minute,
})

// URL
opt, _ := redis.ParseURL("redis://localhost:6379/?conn_max_lifetime=1h&conn_max_lifetime_jitter=5m")