After SUBSCRIBE in CLUSTER mode, an error is thrown when slots are refreshed

[natesilva]

When you have a CLUSTER connection and you issue the SUBSCRIBER command, ioredis continues to periodically refresh its slots cache by calling CLUSTER slots.

When this happens, an error is thrown (see lib/redis.js line 571): https://github.com/luin/ioredis/blob/ec1e85267f79c31825a0340f981be94f8edbed2d/lib/redis.js#L570-L573

I don’t know Redis well enough to know if CLUSTER slots should be allowed here, but this seems like a bug: either CLUSTER slots should be added to the VALID_IN_SUBSCRIBER_MODE list, or it should stop refreshing slots once it’s in SUBSCRIBER mode.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed after 7 days if no further activity occurs, but feel free to re-open a closed issue if needed.

[natesilva]

This issue hasn’t been fixed, stalebot. Please keep it open.

[luin]

@natesilva This issue should have been fixed in v4.0.1 (#697). Doesn't it work for you?

[natesilva]

I can’t reproduce the error now. We are using v4.5.1 and I was able to reproduce it recently with a minimal test case, but now I can’t. 🤷🏽‍♂️ Closing, will reopen if it happens again.

[nolimitdev]

@natesilva
I found this bug today and I wanted to fill new issue with title Subscribe in cluster causes Unhandled error event after node is disconnected but I found this very similar issue. I think it is the same. I think this issue should be re-opened. I reproduced this error on ioredis v4.5.1 on linux debian and windows too with identical result so I will demonstrate for example result from windows.

It is not possible to avoid "Unhandled error event" in combination redis cluster + used subscribe + cluster node or all nodes goes down. There is no bug in non-cluster version but only in cluster version. I will show you results for non-cluster version (single node on port 6379) and cluster version (with 2 nodes on ports 7008 and 7009). I also tested two alternatives "A" without subscribe and "B" with subscribe.

---

Non-cluster (OK)

Start redis single node, then run node non-cluster.js and few seconds later shutdown node...

// file non-cluster.js
var ioredis = require('ioredis');
var redis = new ioredis({host: 'localhost', port: 6379});

redis.on('error', function(error) {
    console.log('Redis error:', error.message);
});

redis.on('ready', function() {
    console.log('Redis is ready');
});

// I will test "A" alternative without this subscribe code and "B" alternative with it
redis.subscribe('item', function(error, count) {
    if (error)
        console.log('Subscribe error:', error.message);
    else
        console.log('Subscribe count:', count);
});

// A - without subscribe:

Redis is ready
Redis error: read ECONNRESET
Redis error: connect ECONNREFUSED 127.0.0.1:6379
Redis error: connect ECONNREFUSED 127.0.0.1:6379
Redis error: connect ECONNREFUSED 127.0.0.1:6379
...

// B - with subscribe:

Redis is ready
Subscribe count: 1
Redis error: read ECONNRESET
Redis error: connect ECONNREFUSED 127.0.0.1:6379
Redis error: connect ECONNREFUSED 127.0.0.1:6379
Redis error: connect ECONNREFUSED 127.0.0.1:6379
...

There is no "Unhandled error event" in non-cluser version for both alternatives.

---

Cluster (BUG)

Start redis cluster, then run node cluster.js and few seconds later shutdown both cluster nodes...

// file cluster.js
var ioredis = require('ioredis');
var nodes = [{host: 'localhost', port: 7001}, {host: 'localhost', port: 7002}];
var redis = new ioredis.Cluster(nodes);

redis.on('error', function(error) {
    console.log('Redis cluster error:', error.message);
});

redis.on('ready', function() {
    console.log('Redis cluster is ready');
});

redis.on('node error', function(error) {
    console.log('Redis cluster node error:', error.message);
});

// I will test "A" alternative without this subscribe code and "B" alternative with it
redis.subscribe('item', function(error, count) {
    if (error)
        console.log('Subscribe error:', error.message);
    else
        console.log('Subscribe count:', count);
});

// A - without subscribe:

Redis cluster is ready
Redis cluster node error: timeout
Redis cluster node error: timeout
Redis cluster node error: timeout
Redis cluster node error: Connection is closed.
Redis cluster error: Failed to refresh slots cache.
Redis cluster node error: timeout
Redis cluster node error: timeout
Redis cluster error: Failed to refresh slots cache.
Redis cluster node error: timeout
Redis cluster node error: timeout
Redis cluster error: Failed to refresh slots cache.
Redis cluster node error: timeout
Redis cluster node error: timeout
...

No "Unhandled error event" in cluster version without subscribe.

// B - with subscribe:

Redis cluster is ready
Subscribe count: 1
Redis cluster node error: timeout
Redis cluster node error: timeout
[ioredis] Unhandled error event: Error: connect ECONNREFUSED 127.0.0.1:7001
at TCPConnectWrap.afterConnect [as oncomplete] (net.js:1191:14)
[ioredis] Unhandled error event: Error: connect ECONNREFUSED 127.0.0.1:7001
at TCPConnectWrap.afterConnect [as oncomplete] (net.js:1191:14)
Redis cluster node error: timeout
Redis cluster error: Failed to refresh slots cache.
[ioredis] Unhandled error event: Error: connect ECONNREFUSED 127.0.0.1:7001
at TCPConnectWrap.afterConnect [as oncomplete] (net.js:1191:14)
[ioredis] Unhandled error event: Error: connect ECONNREFUSED 127.0.0.1:7001
at TCPConnectWrap.afterConnect [as oncomplete] (net.js:1191:14)
Redis cluster node error: timeout
...

There is "Unhandled error event" in cluster version with subscribe alternative although all errors all correctly handled including that in subscribe callback. I think that it is unhandled by mistake somewhere in ioredis lib not by lib consumer. I also tried to listen for all cluster events but there is always this unhandled error.

[nolimitdev]

Maybe it will be usefull - similar Unhandled error events from linux - debian:

Redis cluster is ready
Subscribe count: 1
[ioredis] Unhandled error event: Error: write EPIPE
at exports._errnoException (util.js:1050:11)
at WriteWrap.afterWrite [as oncomplete] (net.js:814:14)
[ioredis] Unhandled error event: Error: connect ECONNREFUSED 127.0.0.1:7009
at Object.exports._errnoException (util.js:1050:11)
at exports._exceptionWithHostPort (util.js:1073:20)
at TCPConnectWrap.afterConnect [as oncomplete] (net.js:1093:14)
[ioredis] Unhandled error event: Error: connect ECONNREFUSED 127.0.0.1:7009
at Object.exports._errnoException (util.js:1050:11)
at exports._exceptionWithHostPort (util.js:1073:20)
at TCPConnectWrap.afterConnect [as oncomplete] (net.js:1093:14)
[ioredis] Unhandled error event: Error: connect ECONNREFUSED 127.0.0.1:7009
at Object.exports._errnoException (util.js:1050:11)
at exports._exceptionWithHostPort (util.js:1073:20)
at TCPConnectWrap.afterConnect [as oncomplete] (net.js:1093:14)
[ioredis] Unhandled error event: Error: connect ECONNREFUSED 127.0.0.1:7009
at Object.exports._errnoException (util.js:1050:11)
at exports._exceptionWithHostPort (util.js:1073:20)
at TCPConnectWrap.afterConnect [as oncomplete] (net.js:1093:14)
...

[ioredis-robot]

🎉 This issue has been resolved in version 4.6.1 🎉

The release is available on:

• npm package (@next dist-tag)
• GitHub release

Your semantic-release bot 📦🚀