Subscribers don't reconnect to the subscription when there is no traffic

[ArtEE98]

I am using StreamingPull mechanism to receive messages from the Pub/Sub.

Here is only 2 overriding for default SubscriberFactory settings:

@Bean
    public SubscriberFactory subscriberFactory(
            GcpProjectIdProvider id,
            TransportChannelProvider channelProvider,
            CredentialsProvider credentialsProvider) throws IOException {
        PubSubConfiguration config = new PubSubConfiguration();
        config.initialize(id.getProjectId());
        config.getSubscriber().setParallelPullCount(2); //overriding1
        config.getSubscriber().setMaxDurationPerAckExtension(0); //overriding2
        DefaultSubscriberFactory factory = new DefaultSubscriberFactory(id, config);
        factory.setChannelProvider(channelProvider);
        factory.setPullEndpoint(url());
        factory.setCredentialsProvider(credentialsProvider);
        return factory;
    }

The second overriding helps me to resolve this issue: https://stackoverflow.com/questions/77711978/my-subscriber-receive-a-message-from-gcp-subscription-with-exactly-60-seconds-de

I don't have any other overriding, but when there is no trafic I get this picute of number_of_open_streaming_pull subscription metric:

I know that Pub/Sub prefers to avoid a long-running sticky connection and client library should reopens a StreamingPull connection.. It works well when there is an active traffic. Any advice I can achive a stable reopens even when there is no traffic?

I found some issues about this: https://github.com/spring-attic/spring-cloud-gcp/issues/1005 - resolved as internal pub/sub issue https://github.com/spring-attic/spring-cloud-gcp/issues/2552 - adviced to use Synchronous Pull, but I want to go further with Asynchronous pull because for my app lower latency and higher throughput are very important.

We use spring-cloud-gcp-pubsub:5.0

[ldetmer]

Hi @ArtEE98, is this still an issue? Can you share a little more information on the problem please? Is the issue that you want the stream to show up in number_of_open_streaming_pull even if there is no active traffic? Can I ask what your specific use case is?

[ldetmer]

I performed a test where I left a subscriber running for 2 hours without traffic. After 2 hours I was able to send a message and have the subscriber reconnect and receive the message. I will close out for now, but @ArtEE98 if you are able to reproduce please send me additional details about your setup.