源码-redis-2

走读 Redis 代码的时候，发现有一处代码注释的序号不连续，又起了好奇心。翻了翻源码，在 commit <3fd43062c8127857f98c09a06bf70710b2dc2f68¹>，这处改动是调整 gossip sections 的大小。

    /* Don't include this node: the whole packet header is about us
         * already, so we just gossip about other nodes. */
        if (this == myself) continue;

    /* In the gossip section don't include:
     * 1) Nodes in HANDSHAKE state.
     * 3) Nodes with the NOADDR flag set.
     * 4) Disconnected nodes if they don't have configured slots.
     */

git message 摘录如下：

Cluster: use a number of gossip sections proportional to cluster size.

Otherwise it is impossible to receive the majority of failure reports in the node_timeout*2 window in larger clusters.

Still with a 200 nodes cluster, 20 gossip sections are a very reasonable amount of bytes to send.

A side effect of this change is also fater cluster nodes joins for large clusters, because the cluster layout makes less time to propagate.