[Bug]: streams.events.maxLen queue option has no effect

[f-w]

Version

v5.21.1

Platform

NodeJS

What happened?

I set queue option streams.events.maxLen to 10, confirmed Redis key bull:<queueName>:meta field opts.maxLenEvents is 10. Still bull:<queueName>:events count exceeds 10.

How to reproduce.

1. get redis running on 127.0.0.1:6379
2. put following code in a .ts file and run using ts-node.

   import { Queue, Worker } from 'bullmq';
   
   const myQueue = new Queue('foo', {
     connection: {
       host: '127.0.0.1',
       port: 6379,
     },
     defaultJobOptions: {
       removeOnComplete: true,
     },
     streams: {
       events: {
         maxLen: 10,
       },
     },
   });
   
   async function addJobs() {
     for (let i = 0; i < 10; i++) {
       await myQueue.add('myJobName', {
         count: i,
       });
     }
   }
   
   addJobs();
   new Worker(
     'foo',
     async (job) => {
       console.log({ ...job.data, time: new Date() });
     },
     {
       connection: {
         host: '127.0.0.1',
         port: 6379,
       },
     },
   );

3. Inspect Redis bull.foo.events key. Will exceeds 10 when all jobs are processed.

Code of Conduct

• I agree to follow this project's Code of Conduct

[manast]

Unfortunately it is not possible in Redis to trim the streams to an exact value as that would be too slow, so we use "nearly exact trimming": https://redis.io/docs/latest/commands/xtrim/