Sharding

What is sharding

Sharding is multiple connections to discord. It's used when you have a lot of guilds. Discord requires you to have a max of 2,500 guilds per shard, but the recommended is 1 shard per thousand guilds. Discord4J's system is that each DiscordClient you have is one shard, the default when creating a client is a total shard count of 1 and the current shard index is 0 (shards are zero based index), if you wanted to make another shard you'd have to make another DiscordClient.

Coordinate multiple shards

Within the same JVM instance

The following example will allow you to initialize multiple shards from the same place. They will be pre-configured with the necessary components to coordinate their Stores, Rate limits and Gateway connection restrictions.

new ShardingClientBuilder(token)
		.build()
		.map(builder -> builder.setInitialPresence(Presence.invisible()))
		.map(DiscordClientBuilder::build)
		.flatMap(DiscordClient::login)
		.blockLast();

Notice that no shard count is specified. This is because calling ShardingClientBuilder this way will use the recommended amount of shards. If you're looking to set an specific number of shards to connect, look at this example:

new ShardingClientBuilder(token)
		.setShardCount(shardCount)
		.build()
		.map(DiscordClientBuilder::build)
		.flatMap(DiscordClient::login)
		.blockLast();

Notice the line .setShardCount(shardCount). In both cases you can further configure each individual client within a map operator below .build().

To summarize:

new ShardingClientBuilder(token)
		.build()
		// you have access to each individual DiscordClientBuilder for every shard
		.map(builder -> builder.setInitialPresence(Presence.invisible()))
		.map(DiscordClientBuilder::build)           // build each shard client
		.flatMap(DiscordClient::login)              // login each shard
		.blockLast();                               // wait until they disconnect

Across multiple processes

This section is a work in progress! 👷 🏗

This capability will target Discord4J v3.1 to consolidate all coordination components require to operate an architecture like the following: