Blocking not working properly in case of reconnections

There is this older issue https://github.com/luin/ioredis/issues/610 also created by me. But since this is rather important I would like to create a new one with a very specific code to reproduce the issue easily so that it can be resolved once and for all 😃.

This is the code:

async function main() {
  const client = new Redis();

  client.on('error', err => console.log('Redis error', err));
  client.on('reconnecting', msg => console.log('Redis reconnecting...', msg));
  client.on('close', () => console.log('Redis closed...'));
  client.on('connect', () => console.log('Redis connected...'));

  while (true) {
    try {
      console.log('going to block');
      const value = await client.brpoplpush('a', 'b', 4);
      console.log('unblocked', value);
    } catch (err) {
      console.error('ERROR', err);
    }
  }
}

main();

How to reproduce

Just run the code above with a local redis server. The while loop will run forever outputting the following:

going to block
Redis connected...
unblocked null
going to block
unblocked null
going to block
unblocked null
going to block

It just blocks for up to 4 seconds, then unblocks, and so on. Now, while this program is running just stop the redis server, wait a couple of seconds and start it again:

Output would look like this:

Redis closed...
Redis reconnecting... 50
Redis connected...
Redis closed...
Redis reconnecting... 100
Redis error Error: connect ECONNREFUSED 127.0.0.1:6379
    at TCPConnectWrap.afterConnect [as oncomplete] (net.js:1141:16) {
  errno: 'ECONNREFUSED',
  code: 'ECONNREFUSED',
  syscall: 'connect',
  address: '127.0.0.1',
  port: 6379
}
...
...
Redis closed...
Redis reconnecting... 700
Redis connected...

And thats all. The while loop will not continue running as if the call to client.brpoplpush has hanged forever.

Expected results

I expect that as soon as the the client disconnects the call to client.brpoplpush rejects the promise with a connection error. Client code should be able to handle calling again to this blocking command.

I am a bit surprised no one else has reported this issue, I wonder if there is some wrong expectation from my side or if I am using the library incorrectly, if so please let me know since this issue is quite severe for users of Bull/BullMQ libraries.

[JJCella]

I manage to reproduce this issue : it occurs when retryStrategy is returning values less than 50 (exp(0), exp(1), exp(2) in the code snippet below, BullMQ default)

Cannot reproduce with ioredis default retryStrategy Math.min(times * 50, 2000); because returning always numbers >= 50 https://github.com/luin/ioredis/blob/0db2d4f5f27d7106832c934a798e616836d1d0a6/lib/redis/event_handler.ts#L181

ioredis v5.2.3

node -v
v16.16.0

docker run -p 6379:6379 redis

redis-cli
127.0.0.1:6379> INFO
# Server
redis_version:7.0.5

import Redis from 'ioredis';

async function main() {

    // https://github.com/taskforcesh/bullmq/blob/0fb2964151166f2aece0270c54c8cb4f4e2eb898/src/classes/redis-connection.ts#L62
    const retryStrategy = (times: number) => Math.min(Math.exp(times), 20000);
    const client = new Redis({ retryStrategy });

    client.on('error', err => console.log('Redis error', err));
    client.on('reconnecting', msg => console.log('Redis reconnecting...', msg));
    client.on('close', () => console.log('Redis closed...'));
    client.on('connect', () => console.log('Redis connected...'));

    while (true) {
        try {
            console.log('brpoplpush');
            await client.brpoplpush('a', 'b', 4);
            console.log('brpoplpush end');
        } catch (err) {
            console.error('error', err);
        }
    }
}

main().catch();

Output :

brpoplpush
Redis connected...
Redis closed...
Redis reconnecting... 2.718281828459045
Redis connected...
Redis error Error: read ECONNRESET
    at TCP.onStreamRead (node:internal/stream_base_commons:217:20) {
  errno: -104,
  code: 'ECONNRESET',
  syscall: 'read'
}
Redis closed...
Redis reconnecting... 7.38905609893065
Redis error Error: connect ECONNREFUSED 127.0.0.1:6379
    at TCPConnectWrap.afterConnect [as oncomplete] (node:net:1187:16) {
  errno: -111,
  code: 'ECONNREFUSED',
  syscall: 'connect',
  address: '127.0.0.1',
  port: 6379
}
Redis closed...
Redis reconnecting... 20.085536923187668
Redis error Error: connect ECONNREFUSED
Redis closed...
Redis reconnecting... 54.598150033144236
Redis error Error: connect ECONNREFUSED
Redis closed...
Redis reconnecting... 148.4131591025766
Redis error Error: connect ECONNREFUSED
Redis closed...
Redis reconnecting... 403.4287934927351
Redis error Error: connect ECONNREFUSED
Redis closed...
Redis reconnecting... 1096.6331584284585
Redis connected...

[luin]

Anyone that can reproduce this issue can you enable the debug log (DEBUG=ioredis* node yourapp) and post the logs here? Also, we just updated a new version (v4.24.2) with a connection-related fix, I don’t think they’re related though but can you try with the latest version to make sure?