tarfile Module Complexity

The tarfile module provides tools for working with TAR archives.

Functions & Methods

Operation	Time	Space	Notes
TarFile.open(name)	O(n)	O(n)	Open and read directory
TarFile.getmembers()	O(n)	O(n)	Get all member info, n = file count
TarFile.getmember(name)	O(n)	O(1)	Linear search through headers
TarFile.extractfile(name)	O(m)	O(m)	Extract single file, m = size
TarFile.extract(name)	O(m)	O(m)	Extract to filesystem
TarFile.extractall()	O(m)	O(m)	Extract all files
TarFile.add(name)	O(m)	O(k)	Add file, k = buffer size

Opening Archives

Time Complexity: O(n)

Where n = number of files in archive (reading headers).

import tarfile

# Opening TAR: O(n) where n = number of files
# Reads all headers sequentially
with tarfile.open('archive.tar', 'r') as tar:
    # O(n) to process headers
    members = tar.getmembers()  # O(n)

Space Complexity: O(n)

import tarfile

# Memory for member information
with tarfile.open('archive.tar', 'r') as tar:
    # Stores info for all files: O(n)
    members = tar.getmembers()  # O(n) memory

Reading Members

Time Complexity: O(n) for lookup, O(m) for read

Where n = number of files, m = file size.

import tarfile

with tarfile.open('archive.tar', 'r') as tar:
    # Finding member: O(n) linear search
    # (no index, searches headers sequentially)
    member = tar.getmember('file.txt')  # O(n)

    # Reading file: O(m)
    f = tar.extractfile('file.txt')  # O(m)
    content = f.read()  # O(m)

Space Complexity: O(m)

import tarfile

with tarfile.open('archive.tar', 'r') as tar:
    # Full file loaded to memory
    f = tar.extractfile('large.bin')
    content = f.read()  # O(m) space

    # Streaming alternative
    f = tar.extractfile('file.txt')
    while True:
        chunk = f.read(4096)  # O(k) per chunk
        if not chunk:
            break
        process(chunk)

Listing Contents

Time Complexity: O(n)

Where n = number of files in archive.

import tarfile

with tarfile.open('archive.tar', 'r') as tar:
    # Get all members: O(n)
    # Parses all headers
    members = tar.getmembers()  # O(n)

    # List names: O(n)
    names = tar.getnames()  # O(n)

    # Get single member: O(n)
    # Must search through headers
    member = tar.getmember('specific.txt')  # O(n)

Space Complexity: O(n)

import tarfile

with tarfile.open('archive.tar', 'r') as tar:
    # Stores all member information
    members = tar.getmembers()  # O(n) memory

Extracting Files

Time Complexity: O(m)

Where m = total size of extracted files.

import tarfile

with tarfile.open('archive.tar', 'r') as tar:
    # Extract single file: O(m)
    # m = file size
    tar.extract('file.txt')  # O(m)

    # Extract all: O(sum of sizes)
    # Processes each file sequentially
    tar.extractall()  # O(m) where m = total uncompressed size

    # Extract with path: O(m) + filesystem I/O
    tar.extractall(path='output_dir')  # O(m)

Space Complexity: O(k)

Where k = buffer size during extraction.

import tarfile

# Extraction uses streaming buffers
with tarfile.open('archive.tar', 'r') as tar:
    tar.extractall()  # O(k) space, k = buffer size
                      # NOT O(m), memory efficient

Creating Archives

Time Complexity: O(m)

Where m = total size of files added.

import tarfile

# Creating TAR: O(m) per file added
with tarfile.open('output.tar', 'w') as tar:
    # Add single file: O(m)
    tar.add('file.txt')  # O(m)

    # Add multiple: O(sum of sizes)
    tar.add('dir/')  # O(m) for directory contents

Space Complexity: O(k)

Where k = buffer size (not O(m) for entire file).

import tarfile

# TAR uses streaming buffers
with tarfile.open('output.tar', 'w') as tar:
    # Efficient streaming
    tar.add('large_file.bin')  # O(k) buffer, not O(m)

Compression Methods

Uncompressed (tar)

import tarfile

# No compression: fastest
with tarfile.open('archive.tar', 'w') as tar:
    tar.add('file.txt')  # O(m) time, minimal overhead

GZIP Compression (tar.gz)

import tarfile

# GZIP compression: O(m) time with constant factor for compression
with tarfile.open('archive.tar.gz', 'w:gz') as tar:
    tar.add('file.txt')  # O(m) with compression overhead

BZIP2 Compression (tar.bz2)

import tarfile

# BZIP2: Better compression, slower (block sorting)
with tarfile.open('archive.tar.bz2', 'w:bz2') as tar:
    tar.add('file.txt')  # O(m) with higher constant factor than gzip

XZ Compression (tar.xz)

import tarfile

# XZ: Best compression ratio, slowest
with tarfile.open('archive.tar.xz', 'w:xz') as tar:
    tar.add('file.txt')  # O(m) with highest constant factor

Common Patterns

Iterating Members

import tarfile

# Efficient streaming: O(n) iterations
with tarfile.open('archive.tar', 'r') as tar:
    for member in tar:  # O(n) members
        if member.isfile():
            f = tar.extractfile(member)  # O(m) per file
            data = f.read()  # O(m)
            # Process data

Selective Extraction

import tarfile

# Extract only matching files: O(n) to scan, O(subset size) to extract
with tarfile.open('archive.tar', 'r') as tar:
    for member in tar:  # O(n) to iterate
        if member.name.endswith('.txt'):
            tar.extract(member)  # O(m) for this file

Creating Archive from Directory

import tarfile
import os

# Add entire directory: O(sum of all file sizes)
with tarfile.open('backup.tar.gz', 'w:gz') as tar:
    tar.add('my_dir')  # O(m) for all files in directory
                       # Compression adds constant factor overhead

Streaming Large Archives

import tarfile

# Memory-efficient streaming: O(k) memory
with tarfile.open('archive.tar.gz', 'r:gz') as tar:
    for member in tar:  # Streams through archive
        if member.isfile():
            f = tar.extractfile(member)
            while True:
                chunk = f.read(4096)  # O(k) buffer
                if not chunk:
                    break
                process_chunk(chunk)

Performance Characteristics

Best Practices

import tarfile

# Good: Use context manager
with tarfile.open('archive.tar', 'r') as tar:
    data = tar.extractfile('file.txt').read()  # Auto cleanup

# Avoid: Manual file handling
tar = tarfile.open('archive.tar', 'r')
data = tar.extractfile('file.txt').read()
tar.close()  # Must remember to close

# Good: Stream large files
with tarfile.open('archive.tar', 'r') as tar:
    f = tar.extractfile('huge.bin')
    for chunk in iter(lambda: f.read(8192), b''):
        process(chunk)  # O(k) memory per chunk

# Avoid: Load entire large file
with tarfile.open('archive.tar', 'r') as tar:
    data = tar.extractfile('huge.bin').read()  # O(m) memory

Compression Trade-offs

import tarfile

# No compression: fastest write, largest file
with tarfile.open('archive.tar', 'w') as tar:
    tar.add('files')  # Fastest

# GZIP: Good balance, moderate compression
with tarfile.open('archive.tar.gz', 'w:gz') as tar:
    tar.add('files')  # Medium speed, good ratio

# BZIP2: Better compression, slower
with tarfile.open('archive.tar.bz2', 'w:bz2') as tar:
    tar.add('files')  # Slower but better compression

# XZ: Best compression, slowest
with tarfile.open('archive.tar.xz', 'w:xz') as tar:
    tar.add('files')  # Slowest, best compression ratio

Differences from ZIP

# TAR: Streaming, O(k) memory for extraction
# ZIP: Requires reading central directory, O(n) initial memory
# TAR: Sequential access, O(n) to find file
# ZIP: Random access, O(n) but more predictable

Version Notes

• Python 2.3+: Basic tarfile support
• Python 2.7+: Enhanced features
• Python 3.0+: Improved compression support
• Python 3.3+: Support for XZ compression

Related Documentation

• zipfile Module - ZIP archive handling
• gzip Module - GZIP compression
• bz2 Module - BZIP2 compression