Use BufferedOutputStream when writing the Zip file to improve performance - #1579
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When not using STORED entries use a BufferedOutputStream to avoid lots of small writes to the file system. Testing this with a 300mb jar build I see the total build time going from 40s to 30s. Note that it is not possible to do this with STORED entries as the implementation requires a RandomAccessFile to update the CRC after write.
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August 4, 2025 22:13
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Pull Request Overview
This PR improves ZIP file creation performance by using BufferedOutputStream for non-STORED compression methods. The change conditionally wraps the file output stream with a buffer to reduce system call overhead during ZIP file writing.
Key changes:
- Modified DefaultZipCompressor to conditionally use BufferedOutputStream based on compression method
- Added changelog entry documenting the performance improvement
Reviewed Changes
Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.
| File | Description |
|---|---|
| DefaultZipCompressor.groovy | Adds conditional buffering logic to improve ZIP writing performance for non-STORED entries |
| README.md | Documents the performance improvement in the changelog |
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src/main/groovy/com/github/jengelman/gradle/plugins/shadow/internal/DefaultZipCompressor.groovy
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### What changes were proposed in this pull request? This PR aims to upgrade `com.gradleup.shadow` to 8.3.9. ### Why are the changes needed? To bring the latest bug fixed versions. - https://github.com/GradleUp/shadow/releases/tag/8.3.9 - GradleUp/shadow#1579 - https://github.com/GradleUp/shadow/releases/tag/8.3.8 - GradleUp/shadow#1493 - GradleUp/shadow#1488 - https://github.com/GradleUp/shadow/releases/tag/8.3.7 - GradleUp/shadow#1470 ### Does this PR introduce _any_ user-facing change? No. ### How was this patch tested? Pass the CIs. ### Was this patch authored or co-authored using generative AI tooling? No. Closes #469 from dongjoon-hyun/SPARK-55102. Authored-by: Dongjoon Hyun <dongjoon@apache.org> Signed-off-by: Dongjoon Hyun <dongjoon@apache.org>
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When not using STORED entries use a BufferedOutputStream to avoid lots of small writes to the file system.
Testing this with a 300mb jar build I see the total build time going from 40s to 30s.
Note that it is not possible to do this with STORED entries as the implementation requires a RandomAccessFile to update the CRC after write.