How to list / delete uncommitted blob blocks, to avoid: "The uncommitted block count cannot exceed the maximum limit of 100,000 blocks."

Question

How to list / delete uncommitted blob blocks, to avoid: "The uncommitted block count cannot exceed the maximum limit of 100,000 blocks."

Slavomir 5

I am uploading files to azure blob storage (~1.4 GB) via Java SDK using com.azure.storage.blob.specialized.BlockBlobClient. In some situation my program was terminated before committing the uploaded blobs (application had a short timeout before interrupting). As this happened for a lot of files, it seems I have reached near the limit of 100 000 uncommitted blocks. Now when I try to upload such a file again, it fails with:

com.azure.storage.blob.models.BlobStorageException: Status code 409, "<?xml version="1.0" encoding="utf-8"?<Error><Code>BlockCountExceedsLimit</Code><Message>The uncommitted block count cannot exceed the maximum limit of 100,000 blocks.

I found this troubleshooting page related to my issue: https://learn.microsoft.com/en-us/troubleshoot/azure/general/invalid-blob-or-block-content-or-invalid-block-list

"Solution 1" Waiting 7 days, does not sound serious. It is not a real option for me.

Solution 2 : ... In my case I don't know what is "the same blob name". I lost the information which blobs uploads were interrupted. So this solution seems not applicable to me. Is there any way how to figure them out?

Solution 3 : I tried to get uncommitted blocks but again to get the uncommitted block list I need first to know the original blob name. Something like: containerClient.getBlobClient(<the_name>).getBlockBlobClient()..listBlocks(BlockListType.UNCOMMITTED).getUncommittedBlocks();

Is that correct? How can I take the names of the blobs with uncommitted blocks?

I would like to delete those uncommitted blocks. But I cannot reach them. Is there a way to see them form the Azure portal, in the storage browser? Maybe to filter by blobs having uncommitted blocks?

Best regards,

Slavomir

KarishmaTiwari-MSFT 20,772 Reputation points Microsoft Employee Moderator

2023-06-08T02:25:21.5933333+00:00

@Slavomir Thanks for posting your query on Microsoft Q&A.

Could you try listing all the blobs in container using https://learn.microsoft.com/en-us/azure/storage/blobs/storage-blobs-list-java#use-a-flat-listing and
then loop them through to identify blobs with uncommitted blocks using containerClient.getBlobClient(<the_name>).getBlockBlobClient().listBlocks(BlockListType.UNCOMMITTED).getUncommittedBlocks();

2 answers

Your answer

KarishmaTiwari-MSFT 20,772 Reputation points Microsoft Employee Moderator

2023-06-08T02:25:21.5933333+00:00

@Slavomir Thanks for posting your query on Microsoft Q&A.

Could you try listing all the blobs in container using https://learn.microsoft.com/en-us/azure/storage/blobs/storage-blobs-list-java#use-a-flat-listing and
then loop them through to identify blobs with uncommitted blocks using containerClient.getBlobClient(<the_name>).getBlockBlobClient().listBlocks(BlockListType.UNCOMMITTED).getUncommittedBlocks();

Answer 1

Slavomir Grigorov 0

I found a bug in the upload code that in deed caused much small blocks to be uploaded, therefore too many blocks were created. Now it is fixed and the upload works.

If I will have some time I will have time I will investigate the procedure for detecting uncommitted blocks.

Thanks and sorry for the confusion.

KarishmaTiwari-MSFT 20,772 Reputation points Microsoft Employee Moderator

2023-06-13T00:34:13.4233333+00:00

@Slavomir Grigorov Thanks for sharing the update.

Answer 2

KarishmaTiwari-MSFT 20,772 Microsoft Employee Moderator

@Slavomir I'm glad that you were able to resolve your issue and thank you for posting your solution so that others experiencing the same thing can easily reference this!

Since the Microsoft Q&A community has a policy that "The question author cannot accept their own answer. They can only accept answers by others ", I'll repost your solution in case you'd like to "Accept " the answer. Accepted answers show up at the top, resulting in improved discoverability for others.

Cx shared -

Issue: "I received the error - 'The uncommitted block count cannot exceed the maximum limit of 100,000 blocks', while uploading files to Azure Blob Storage. How can I find and delete the uncommitted blocks to resolve this?"

Cause: I found a bug in my upload code that indeed caused much small blocks to be uploaded, therefore too many blocks were created. Now it is fixed, and the upload works.

Suggested approach:
A way to find identify blobs with uncommitted blocks is to try listing all the blobs in container using https://learn.microsoft.com/en-us/azure/storage/blobs/storage-blobs-list-java#use-a-flat-listing and
then loop them through to identify blobs with uncommitted blocks using containerClient.getBlobClient(<the_name>).getBlockBlobClient().listBlocks(BlockListType.UNCOMMITTED).getUncommittedBlocks();

If your issue remains unresolved or have further questions, please let us know in the comments how we can assist. We are here to help you and strive to make your experience better and greatly value your feedback.

Slavomir 5

Unfortunately I cannot accept the answer. (By the way the hyperlink for flat listing points back to this thred) Using a flat list as suggested for the whole container could mean that if you have 1 million blobs there it would loop over 1 million blobs asking azure over and over again to return the uncommitted blobs. This is not acceptable. Also For blobs that have reserved URL characters in it's name, it does not work as well, when trying to url-encode them before invoking getBlobClient it says the blob does not exist.

In case someone would be interested how to ensure that you fill your buffer before uploading the block here is some usable code.

private int readFromStreamTillTheBufferIsFullOrStreamEnds(InputStream inputStream, byte[] buffer) throws IOException, InterruptedException {
    int alreadyReadBytes = 0;
    int consequentZeroReadCounter = 0;
    final int retryLimit = 1000;
    final int waitMillis = 50;
    while (alreadyReadBytes < buffer.length) {
        int bytesToRead = buffer.length - alreadyReadBytes;
        int currentReadCount = inputStream.read(buffer, alreadyReadBytes, bytesToRead);
        if (currentReadCount == -1) {
            if (alreadyReadBytes == 0) {
                return -1;
            }
            break;
        } else if (currentReadCount == 0) {
            if (consequentZeroReadCounter > retryLimit) {
                throw new InterruptedException("Unable to read the input stream, no new data available for about " + (waitMillis * retryLimit) + " milliseconds.");
            }
            ++consequentZeroReadCounter;
            Thread.sleep(waitMillis); // This is necessary to give chance to some bytes on the input stream to become available.
        } else {
            alreadyReadBytes += currentReadCount; // usually only 16K is available in the input stream
            consequentZeroReadCounter = 0;
        }
    }
    log.debug("Read from input to buffer: " + alreadyReadBytes);
    return alreadyReadBytes;
}

Best regards,

Slavomir

KarishmaTiwari-MSFT 20,772 Reputation points Microsoft Employee Moderator

2023-06-14T17:33:29.0133333+00:00

@Slavomir That makes sense. Thanks for sharing your code to avoid this situation in the first place.

Thanks for pointing it out, I have updated the link. But I understand that it may not be useful in this scenario.

Share via

How to list / delete uncommitted blob blocks, to avoid: "The uncommitted block count cannot exceed the maximum limit of 100,000 blocks."

2 answers

Your answer