async-unzip 0.5.2

Async unzipping to prevent asyncio timeout errors and decrease the memory usage for bigger zip files

async-unzip

Asynchronous unzipping of big files with low memory usage in Python Helps with big zip files unpacking (memory usage + buffer_size could be changed). Also, prevents having Asyncio Timeout errors especially in case of many workers using same CPU cores.

Fully tested on Python 3.7 through 3.14.

By default the extractor schedules up to 4 concurrent workers using the stdlib zlib backend. Tune concurrency via the max_workers argument, and install python-isal or zlib-ng if you want to force those accelerators via the optional backend parameter:

asyncio.run(unzip('archive.zip', path='output', max_workers=8))

When uvloop is installed, the event loop policy switches automatically to leverage its faster reactor.

When python-isal or zlib-ng is installed you can opt into them via backend="python-isal" or backend="zlib-ng"; otherwise the stdlib zlib backend remains the default.

Usage Examples

import asyncio
from async_unzip import unzipper

# Basic usage (defaults to stdlib zlib, max_workers=4)
asyncio.run(unzipper.unzip("tests/test_files/fixture_beta.zip", path="output"))

# Force python-isal backend and custom worker count
asyncio.run(
    unzipper.unzip(
        "tests/test_files/fixture_gamma.zip",
        path="output_isal",
        backend="python-isal",
        max_workers=2,
    )
)

# Specify a whitelist of files and a regex filter
asyncio.run(
    unzipper.unzip(
        "archive.zip",
        path="filtered",
        files=["docs/readme.txt"],
        regex_files=[r"images/.*\\.png$"],
    )
)

Optional backends

pip install python-isal    # to enable backend="python-isal"
pip install zlib-ng        # to enable backend="zlib-ng"

Benchmark script

Use the helper under scripts/bench_async_metrics.py to reproduce the CPU/memory data in the tables below:

python scripts/bench_async_metrics.py \
  --archives tests/test_files/fixture_gamma.zip \
             large:~/Downloads/some_large.zip \
  --workers 1 2 4 \
  --backend zlib-ng \
  --samples 3

Benchmarks

Numbers below were captured on an Apple Silicon macOS Sonoma machine (ARM64). Each measurement extracts into a fresh temporary directory and averages three runs.

Synthetic archive (tests/test_files/fixture_gamma.zip, 23.7 MB)

Backend	Workers	Avg time (s)	CPU avg / max (%)	RAM avg / max (MB)
zlib	1	0.91	85.7 / 89.3	29.46 / 29.52
zlib	2	0.80	117.6 / 133.3	32.32 / 32.52
zlib	4	0.70	162.3 / 167.4	33.24 / 33.34
zlib-ng	1	1.00	81.7 / 87.7	29.44 / 29.59
zlib-ng	2	0.80	119.4 / 133.7	32.62 / 32.86
zlib-ng	4	0.82	134.4 / 168.3	33.59 / 33.70
python-isal	1	1.12	76.8 / 92.6	29.71 / 29.84
python-isal	2	0.91	112.4 / 132.0	33.01 / 33.11
python-isal	4	0.80	146.1 / 163.1	34.08 / 34.19

Real dataset (external ZIP, ≈1.10 GB)

Backend	Workers	Avg time (s)	CPU avg / max (%)	RAM avg / max (MB)
zlib	1	9.49	81.2 / 98.4	75.21 / 79.25
zlib	2	8.84	87.6 / 126.2	78.88 / 79.38
zlib	4	8.56	90.2 / 128.1	84.87 / 84.94
zlib-ng	1	13.35	73.0 / 96.7	37.95 / 38.95
zlib-ng	2	13.15	84.1 / 120.1	205.45 / 243.17
zlib-ng	4	12.12	92.4 / 121.7	218.62 / 244.89
python-isal	1	20.00	95.8 / 100.0	37.58 / 38.33
python-isal	2	21.76	96.2 / 110.5	202.98 / 244.09
python-isal	4	22.00	96.2 / 112.5	217.48 / 246.03

The large archive is not part of this repository; download any similarly sized ZIP manually if you want to reproduce the numbers.

Synchronous zipfile.ZipFile.extractall() (same 1.10 GB dataset)

Backend	Avg seconds	Samples (s)
zlib	14.42	14.58, 14.53, 14.16
zlib-ng	14.94	14.98, 14.99, 14.83
python-isal	14.04	13.92, 14.24, 13.94

zipfile is single-threaded, so concurrency does not apply in this scenario.

From version 0.3.6 module doesn't require, but expects to have aiofile OR aiofiles to be installed for I/O operations. However, aiofile is recommended for linux, just don't forget to install libaio (libaio1) linux module (e.g., apt install -y libaio1 for debian)

from async_unzip.unzipper import unzip
import asyncio

asyncio.run(unzip('tests/test_files/fixture_beta.zip', path='some_dir'))

Changelog

0.5.2

• Added usage examples, backend-installation notes, and benchmark-script instructions.
• Introduced zlib backend selection parameter (backend="...") and made stdlib zlib the explicit default even when accelerators are installed.
• Added deterministic benchmark script under scripts/bench_async_metrics.py for reproducibility.

0.5.1

• Added zlib-ng backend option alongside python-isal and documented how to select backends explicitly.
• Introduced backend registry and optional backend="..." parameter (defaulting to stdlib zlib).
• Documented detailed time/CPU/memory benchmarks for async extraction on Apple Silicon macOS.
• Added synchronous zipfile.extractall() comparison table.

0.5.0

• Added directory-creation caching and adaptive buffer sizing.
• Introduced backend auto-detection for python-isal; updated tests to cover new behaviors.
• Improved README benchmark section.

0.4.x

• Initial async unzipper with concurrency, window-bits caching, and various bug fixes.