Type of Change

• Bug Fix
• Performance Improvement

Related Issues

• Fixes Uploading files of 10GB or 20GB consecutively may cause the upload to freeze. #832

Summary of Changes

Consecutive uploads of 10-20GB files freeze with AwsChunkedStreamError: Underlying: error reading a body from connection. Root cause: StreamReader::new() uses 8KB default buffer, causing ~1.3M syscalls per 10GB file and connection timeouts under AWS chunked encoding overhead.

Solution: Wrap StreamReader with tokio::io::BufReader::with_capacity() using adaptive buffer sizing based on file size to optimize both performance and memory usage.

Changes Made

Modified rustfs/src/storage/ecfs.rs in three critical locations:

• put_object (line ~2369): standard uploads
• put_object_extract (line ~404): archive extraction
• upload_part (line ~2897): multipart uploads

Added adaptive buffer sizing helper function and comprehensive unit tests.

Implementation Details

Since tokio-util 0.7.17 doesn't provide StreamReader::with_capacity(), the fix uses tokio::io::BufReader::with_capacity() to wrap the StreamReader with an adaptively sized buffer.

Adaptive Buffer Sizing Strategy:

• Small files (< 1MB): 64KB buffer - minimize memory overhead
• Medium files (1MB-100MB): 256KB buffer - balanced performance
• Large files (≥ 100MB): 1MB buffer - maximize throughput, minimize syscalls
• Unknown size (chunked): 1MB buffer - safe default for streaming

Before

let body = StreamReader::new(
    body.map(|f| f.map_err(|e| std::io::Error::other(e.to_string())))
);

After

// Use adaptive buffer sizing based on file size for optimal performance
let buffer_size = get_adaptive_buffer_size(size);
let body = tokio::io::BufReader::with_capacity(
    buffer_size,
    StreamReader::new(body.map(|f| f.map_err(|e| std::io::Error::other(e.to_string())))),
);

Checklist

• I have read and followed the CONTRIBUTING.md guidelines
• Passed make pre-commit
• Added/updated necessary tests
• Documentation updated (if needed)
• CI/CD passed (if applicable)

Impact

• Breaking change (compatibility)
• Requires doc/config/deployment update
• Other impact: Performance Improvement & Memory Optimization
  • For 10GB uploads: syscalls reduced 99.2% (1.3M → 10K)
  • For 100KB uploads: memory usage reduced 94% (1MB → 64KB buffer)
  • Eliminates timeout risk for large file uploads
  • Lower CPU overhead from reduced AWS chunked encoding/decoding operations
  • Better memory efficiency with adaptive buffer sizing

Additional Notes

Performance Impact by File Size

Key Improvements

1. Intelligent Buffer Selection: Automatically chooses optimal buffer size based on content-length
2. Memory Efficiency: Small files use smaller buffers, reducing memory waste by up to 94%
3. Performance Preservation: Large files maintain the 99.2% syscall reduction
4. Zero Configuration: Works automatically without manual tuning

Testing

• Added test_adaptive_buffer_size() unit test covering all buffer size ranges
• Tests validate correct buffer selection for unknown, small, medium, and large files

Documentation

Created docs/fix-large-file-upload-freeze.md with comprehensive technical documentation including:

• Problem description and root cause analysis
• Detailed solution explanation with adaptive buffer sizing
• Performance impact analysis with comparison table
• Testing recommendations
• Monitoring metrics
• Implementation details and code examples

Thank you for your contribution! Please ensure your PR follows the community standards (CODE_OF_CONDUCT.md) and sign the CLA if this is your first contribution.

• Fixes Uploading files of 10GB or 20GB consecutively may cause the upload to freeze. #832

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