Preemptively closing pooled H2 connections

[dhalbrook]

We are using a Pool of H2 connections. Currently, when a GOAWAY frame is received, a "connectionError" is emitted, and the connection is removed from the pool by undici. However, we'd like to just preemptively close and remove the connection from the pool based on a configured time, since we already know the max connection lifetime of the origin. I can't seem to figure out a way of doing this.

[mcollina]

Would you like to send a PR?

[dhalbrook]

OK, i'll see what I can figure out and open a PR.

[metcoder95]

Have you tried setting a factory for the clients? There you might be able to somehow get a workaround

[dhalbrook]

I ended up creating this PR: #4175

It adds a "clientLifetime" option to the pool. After the specified amount of time, the client is removed from the pool, then closed.

I've been testing it against our codebase and it performs as expected.

[dhalbrook]

I also figured out a way to do this using factory in Pool options as suggested:

factory: clientOrigin => {
    // remove clients from pool after 30 minutes
    const ttlConfig = ConfigHelper.toNumber(process.env.UNDICI_POOL_CLIENT_LIFETIME,30 * 60 * 1000);
    const client = new Client(clientOrigin, agentOptions);
    if (ttlConfig > 0) {
      client.on('connect', () => {
        Object.assign(client, { ttl: Date.now() });
      });
      client.on('drain', () => {
        const clientTtl = client['ttl'];
        if (clientTtl && Date.now() - clientTtl > ttlConfig) {
          log.debug('Client is expired.  Removing it from pool.');
          // throwing a connection error causes the client to be removed from the pool
          client.emit('connectionError', clientOrigin, [client], null);
        }
      });
    }
    return client;
  },

I don't like that this relies on emitting a synthetic error to remove the client from the pool, but has the intended effect.

[dhalbrook]

Merged into 7.10.0: #4175