azure-sdk-for-java: [QUERY] How to alleviate Timeouts in List Blobs operation?

Query/Question How to alleviate Timeouts in List Blobs operation?

The timeout is set for 30s which is the max permissible for Blob Service ( as per the Azure documentation ). The max number of keys for listing ( maxResultsPerPage ) is the default 5000. The buckets being listed are large buckets with 100k+ objects.

I know that adding a retry is another possibility but would prefer if there was another alternative.

The timeout exception is given below

Caused by: reactor.core.Exceptions$ReactiveException: java.util.concurrent.TimeoutException: Did not observe any item or terminal signal within 30000ms in 'flatMap' (and no fallback has been configured)
        at reactor.core.Exceptions.propagate(Exceptions.java:393) ~[observer-3.20.92.jar:na]
        at reactor.core.publisher.BlockingIterable$SubscriberIterator.hasNext(BlockingIterable.java:168) ~[observer-3.20.92.jar:na]
        at reactor.core.publisher.BlockingIterable$SubscriberIterator.next(BlockingIterable.java:198) ~[observer-3.20.92.jar:na]
        at kdc.cloudadapters.adapters.MicrosoftAzureAdapter$AzureListRequest.nextBatch(MicrosoftAzureAdapter.java:566) ~[observer-3.20.92.jar:na]
        ... 9 common frames omitted

Caused by: java.util.concurrent.TimeoutException: Did not observe any item or terminal signal within 30000ms in 'flatMap' (and no fallback has been configured)
        at reactor.core.publisher.FluxTimeout$TimeoutMainSubscriber.handleTimeout(FluxTimeout.java:289) ~[observer-3.20.92.jar:na]
        at reactor.core.publisher.FluxTimeout$TimeoutMainSubscriber.doTimeout(FluxTimeout.java:274) ~[observer-3.20.92.jar:na]
        at reactor.core.publisher.FluxTimeout$TimeoutTimeoutSubscriber.onNext(FluxTimeout.java:396) ~[observer-3.20.92.jar:na]
        at reactor.core.publisher.StrictSubscriber.onNext(StrictSubscriber.java:89) ~[observer-3.20.92.jar:na]
        at reactor.core.publisher.FluxOnErrorResume$ResumeSubscriber.onNext(FluxOnErrorResume.java:73) ~[observer-3.20.92.jar:na]
        at reactor.core.publisher.MonoDelay$MonoDelayRunnable.run(MonoDelay.java:117) ~[observer-3.20.92.jar:na]
        at reactor.core.scheduler.SchedulerTask.call(SchedulerTask.java:68) ~[observer-3.20.92.jar:na]
        at reactor.core.scheduler.SchedulerTask.call(SchedulerTask.java:28) ~[observer-3.20.92.jar:na]
        at java.util.concurrent.FutureTask.run(FutureTask.java:266) ~[na:1.8.0_252]
        at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$201(ScheduledThreadPoolExecutor.java:180) ~[na:1.8.0_252]
        at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:293) ~[na:1.8.0_252]
       ... 3 common frames omitted

Additional information

A shorter variation of the code used is given below

class AzureList {
        
        BlobContainerClient container;
        Iterator<PagedResponse<BlobItem>> iterator;
        String continuationToken;

        public AzureList(String accountName, String accountKey, String bucketName) {
            StorageSharedKeyCredential credential = new StorageSharedKeyCredential(accountName, accountKey);
            String endpoint = String.format(Locale.ROOT, "https://%s.blob.core.windows.net", accountName);
            BlobServiceClient serviceClient = new BlobServiceClientBuilder().credential(credential)
                                                         .endpoint(endpoint)
                                                         .buildClient();
            container = serviceClient.getBlobContainerClient(bucketName);
            iterator = getIterator(/*prefix*/ "");  // Current use case is just "" as prefix but can be different in the future
            continuationToken = null;
        }
        
        private Iterator<PagedResponse<BlobItem>> getIterator(String prefix) {
            ListBlobsOptions options = new ListBlobsOptions().setPrefix(prefix);
            return container.listBlobs(options, continuationToken, Duration.ofSeconds(30L)).iterableByPage().iterator();
        }
        
        public void iterate() {
            List<BlobItem> blobs;
            do {
                blobs = listBlobs();
                // hand off blob list to different consumer class
            } while (continuationToken != null);
        }

        private List<BlobItem> listBlobs() {
            PagedResponse<BlobItem> pagedResponse = iterator.next();
            List<BlobItem> blobs = pagedResponse.getValue();
            continuationToken = pagedResponse.getContinuationToken();
            return blobs;
        }
    }

Why is this not a Bug or a feature Request? Unsure if it is a Bug or an issue with my local env / my code.

Setup (please complete the following information if applicable):

• OS: Ubuntu 18.04
• IDE : IntelliJ 19.1.4
• SDK: azure-storage-blob v12.7.0

Information Checklist Kindly make sure that you have added all the following information above and checkoff the required fields otherwise we will treat the issuer as an incomplete report

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