Parfive is a small library for downloading files, its objective is to provide a simple API for queuing files for download and then providing excellent feedback to the user about the in progress downloads. It also aims to provide a clear interface for inspecting any failed downloads.
The parfive package was motivated by the needs of SunPy’s
net submodule, but should be generally applicable to anyone who wants a user friendly way of downloading multiple files in parallel.
Parfive uses asyncio to support downloading multiple files in parallel, and to support downloading a single file in multiple parallel chunks.
Parfive supports downloading files over either HTTP or FTP using aiohttp and aioftp (
aioftp is an optional dependency, which does not need to be installed to download files over HTTP).
Parfive provides both a function and coroutine interface, so that it can be used from both synchronous and asynchronous code. It also has opt-in support for using aiofiles to write downloaded data to disk using a separate thread pool, which may be useful if you are using parfive from within an asyncio application.
parfive can be installed via pip:
pip install parfive
or with FTP support:
pip install parfive[ftp]
or with conda from conda-forge:
conda install -c conda-forge parfive
or from GitHub.
Parfive works by creating a downloader object, queuing downloads with it and then running the download.
A simple example is:
from parfive import Downloader dl = Downloader() dl.enqueue_file("http://data.sunpy.org/sample-data/predicted-sunspot-radio-flux.txt", path="./") files = dl.download()
It’s also possible to download a list of URLs to a single destination using the
from parfive import Downloader files = Downloader.simple_download(['http://126.96.36.199/5MB.zip' 'http://188.8.131.52/10MB.zip'], path="./")
Parfive also bundles a CLI. The following example will download the two files concurrently:
$ parfive 'http://184.108.40.206/5MB.zip' 'http://220.127.116.11/10MB.zip' $ parfive --help usage: parfive [-h] [--max-conn MAX_CONN] [--overwrite] [--no-file-progress] [--directory DIRECTORY] [--print-filenames] URLS [URLS ...] Parfive, the python asyncio based downloader positional arguments: URLS URLs of files to be downloaded. optional arguments: -h, --help show this help message and exit --max-conn MAX_CONN Number of maximum connections. --overwrite Overwrite if the file exists. --no-file-progress Show progress bar for each file. --directory DIRECTORY Directory to which downloaded files are saved. --print-filenames Print successfully downloaded files's names to stdout.
Options and Customisation#
Parfive aims to support as many use cases as possible, and therefore has a number of options.
There are two main points where you can customise the behaviour of the downloads, in the initialiser to
parfive.Downloader or when adding a URL to the download queue with
The arguments to the
Downloader() constructor affect all files transferred, and the arguments to
enqueue_file() apply to only that file.
By default parfive will transfer 5 files in parallel and, if supported by the remote server, chunk those files and download 5 chunks simultaneously.
This behaviour is controlled by the
max_splits= keyword arguments.
Further configuration of the
Downloader instance is done by passing in a
parfive.SessionConfig object as the
config= keyword argument to
See the documentation of that class for more details.
Keyword arguments to
enqueue_file are passed through to either
aiohttp.ClientSession.get for HTTP downloads or
aioftp.Client for FTP downloads.
This gives you many per-file options such as headers, authentication, ssl options etc.
Configuration options for
Download files in parallel.
The results of a download from
Class Inheritance Diagram#
Parfive reads the following environment variables, note that as of version 2.0 all environment variables are read at the point where the
Downloader() class is instantiated.
PARFIVE_SINGLE_DOWNLOAD- If set to
"True"this variable sets
max_splitsto one; meaning that no parallelisation of the downloads will occur.
PARFIVE_DISABLE_RANGE- If set to
"True"this variable will set
max_splitsto one; meaning that each file downloaded will only have one concurrent connection, although multiple files may be downloaded simultaneously.
PARFIVE_OVERWRITE_ENABLE_AIOFILES- If set to
"True"and aiofiles is installed in the system, aiofiles will be used to write files to disk.
PARFIVE_DEBUG- If set to
"True"will configure the built-in Python logger to log to stderr and set parfive, aiohttp and aioftp to debug levels.
PARFIVE_HIDE_PROGESS- If set to
"True"no progress bars will be shown.
PARFIVE_TOTAL_TIMEOUT- Overrides the default aiohttp
totaltimeout value (unless set in Python).
PARFIVE_SOCK_READ_TIMEOUT- Overrides the default aiohttp
sock_readtimeout value (unless set in Python).
See GitHub Releases for the release history and changelog.