Performance and Memory Problems

Slow Decompression

Symptoms: Extraction taking excessive time

Causes and Solutions:

  1. Large LZX window

    • Use MSZIP instead of LZX for faster extraction

    • Reduce LZX window size when creating archives

  2. Many small files

    • Extract in parallel if possible

    • Consider batch processing

  3. Slow I/O

    • Use SSD instead of HDD

    • Check disk space and fragmentation

High Memory Usage

Symptoms: Excessive RAM consumption

Solutions:

# Use streaming for large files
File.open('output.dat', 'wb') do |output|
  cab.extract_file('large.dat') do |chunk|
    output.write(chunk)
  end
end

# Process files individually
cab.files.each do |file|
  # Extract one at a time
  data = file.data
  File.write(file.name, data)
  data = nil  # Allow GC
  GC.start
end

Memory Allocation Failures

Error: NoMemoryError or Errno::ENOMEM

Solutions:

  1. Increase system memory

  2. Use smaller compression windows

  3. Close other applications

  4. Process in smaller batches

CPU Usage

Issue: High CPU during compression/decompression

Normal: LZX compression is CPU-intensive

Solutions:

  • Use faster algorithms (MSZIP, None)

  • Reduce compression level

  • Use parallel processing for multiple files

Optimization Tips

  1. Choose appropriate algorithm:

    • Fast: None, LZSS

    • Balanced: MSZIP

    • Maximum compression: LZX

  2. Tune for your use case:

    • One-time: Use maximum compression

    • Frequent access: Use faster algorithms

  3. Monitor resources:

require 'benchmark'

time = Benchmark.measure do
  cab.extract_all('output/')
end

puts "Extraction took #{time.real} seconds"

See also