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Update default max publish batch byte size calculation - #36082

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utsav-pal:Default-Pub/Sub-batch-size-is-smaller-than-the-maximum-message-size-#36067
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Update default max publish batch byte size calculation#36082
utsav-pal wants to merge 1 commit into
apache:masterfrom
utsav-pal:Default-Pub/Sub-batch-size-is-smaller-than-the-maximum-message-size-#36067

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@utsav-pal

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Addresses: #36067

Description:
This PR updates the default value of MAX_PUBLISH_BATCH_BYTE_SIZE_DEFAULT in PubsubIO.java from 7.5MB (((10 * 1000 * 1000) / 4) * 3) to 10MB (10 * 1000 * 1000). This change aligns the Beam Java SDK's default Pub/Sub batch size limit with the documented Google Cloud Pub/Sub maximum message size, preventing unexpected failures when sending messages between 7.5MB and 10MB.

  • The previous default (7.5MB) could cause confusing errors for users sending large messages, despite those messages being under Pub/Sub's official limit.
  • With this change, users can now send any message up to the documented 10MB limit without extra configuration.
  • The code comment is also updated to clarify this default matches the Pub/Sub limit.

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Summary of Changes

Hello @utsav-pal, I'm Gemini Code Assist1! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request aims to enhance the robustness of the Apache Beam Java SDK's Pub/Sub integration by adjusting an internal default configuration. The modification ensures that the SDK's default batch size limit for publishing messages is consistent with the actual maximum message size supported by Google Cloud Pub/Sub. This prevents potential failures for users attempting to send larger, yet valid, messages, thereby improving the out-of-the-box experience.

Highlights

  • Pub/Sub Batch Size Default: The default maximum publish batch byte size (MAX_PUBLISH_BATCH_BYTE_SIZE_DEFAULT) in PubsubIO.java has been updated.
  • Alignment with Pub/Sub Limits: The default value is now 10MB, aligning with Google Cloud Pub/Sub's documented maximum message size, up from the previous 7.5MB.
  • User Experience Improvement: This change prevents unexpected errors for users sending messages between 7.5MB and 10MB, allowing them to send messages up to the official 10MB limit without additional configuration.
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github-actions Bot commented Sep 7, 2025

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Checks are failing. Will not request review until checks are succeeding. If you'd like to override that behavior, comment assign set of reviewers

@sjvanrossum

sjvanrossum commented Sep 8, 2025

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Unless the JSON client has been removed this limit can't be changed yet, see #31800 for details.

TL;DR Base64 encoding outputs 4 bytes for 3 bytes of input, hence the 7.5MB limit, and the /v1/{topic=projects/*/topics/*}:publish method of Pub/Sub's REST API will reject requests that exceed 10MiB (note the i).

@stankiewicz

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there are style errors:


[Incubating] Problems report is available at: file:///runner/_work/beam/beam/build/reports/problems/problems-report.html
* What went wrong:
Execution failed for task ':sdks:java:io:google-cloud-platform:spotlessJavaCheck'.
> The following files had format violations:
      sdks/java/io/google-cloud-platform/src/main/java/org/apache/beam/sdk/io/gcp/pubsub/PubsubIO.java
          @@ -1348,7 +1348,7 @@
           ?????*?Max?batch?byte?size.?Messages?are?base64?encoded?which?encodes?each?set?of?three?bytes?into
           ?????*?four?bytes.
           ?????*/
          -????private?static?final?int?MAX_PUBLISH_BATCH_BYTE_SIZE_DEFAULT?=?10?*?1000?*?1000?;
          +????private?static?final?int?MAX_PUBLISH_BATCH_BYTE_SIZE_DEFAULT?=?10?*?1000?*?1000;
           
           ????private?static?final?int?MAX_PUBLISH_BATCH_SIZE?=?100;
           
  Run './gradlew :sdks:java:io:google-cloud-platform:spotlessApply' to fix these violations.

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This pull request has been marked as stale due to 60 days of inactivity. It will be closed in 1 week if no further activity occurs. If you think that’s incorrect or this pull request requires a review, please simply write any comment. If closed, you can revive the PR at any time and @mention a reviewer or discuss it on the dev@beam.apache.org list. Thank you for your contributions.

@github-actions github-actions Bot added the stale label Nov 24, 2025
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github-actions Bot commented Dec 1, 2025

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This pull request has been closed due to lack of activity. If you think that is incorrect, or the pull request requires review, you can revive the PR at any time.

@github-actions github-actions Bot closed this Dec 1, 2025
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