Cannot subscribe to more than 6 ipfs pubsub channels with ipfs-http-client

Question

I'm currently building a node application with ipfs-http-client.

I need to subscribe to several pubsub channels (~20).

When I'm connecting to the channels, I receive a 200 response for each subscribe, but only the 6 first subscribe are receiving the messages.

I isolated the problem in a little snippet with only:

• Connect to the node (ipfs 0.4.23 and I tried with another one in 0.8)
• Subscribe to 20 channels (with different names or the same channel with different handlers)
• I always reproduce the problem (only connected to the 6 first subscribers)

I'm running my tests with node 14.16.0

When I look into the ipfs-http-client package, I can see that I actually have no response from the http request after the 6 first. Still, no error is reported.

Answer 1

achingbrain answers this question: https://github.com/ipfs/js-ipfs/issues/3741#issuecomment-898344489

In node the default agent used by the http client limits connections to 6 so it's consistent with the browser. You can configure your own agent to change this:

const { create } = require('ipfs-http-client');
const http = require('http')

async function echo(msg) {
    console.log(`TopicID: ${msg.topicIDs[0]}, Msg: ${new TextDecoder().decode(msg.data)}`);
}

async function run() {
    // connect to the default API address http://localhost:5001
    const client = create({
        agent: http.Agent({ keepAlive: true, maxSockets: Infinity })
    });
    console.log(await client.version());

    for (let i = 0; i < 20; i++) {
        await client.pubsub.subscribe(parseInt(i), echo);
    }
}

run();