zipimportx 0.2.0

This package aims to speed up imports from zipfiles, by pre-computing the “directory information” dictionary and storing it in a separate index file. This reduces the time spent parsing information out of the zipfile.

It exports a single useful name, zipimporter, which is a drop-in replacement for the standard zipimporter class.

To create an index for a given zipfile, do the following:

from zipimportx import zipimporter
zipimporter("mylib.zip").write_index()

Depending on your platform, this will create either “mylib.zip.win32.idx” or “mylib.zip.posix.idx” containing the pre-parsed zipfile directory information. (Specifically, it will contain a marshalled dictionary similar to those found in zipimport._zip_directory_cache.)

To enable use of these index files, simply replace the builtin zipimport mechanism with zipimportx by doing the following:

import zipimportx
zipimportx.zipimporter.install()

In my tests, use of these indexes speeds up the initial loading of a zipfile by about a factor of 3 on Linux, and a factor of 5 on Windows.

Note that this package uses nothing but builtin modules. To bootstrap zipfile imports for a frozen application, you can inline the module’s code directly into your application’s startup script. Do this somewhere in your build:

import zipimportx
import inspect

SCRIPT = '''
%s
zipimporter.install()
import myapp
myapp.main()
''' % (inspect.getsource(zipimportx),)

freeze_this_script_somehow(SCRIPT)
zipimportx.zipimporter("path/to/frozen/library.zip").write_indexes()

Note also that imports will almost certainly break if the index does not reflect the actual contents of the zipfile. This module is therefore most useful for frozen apps and other situations where the zipfile is not expected to change.