PyPy2.7 v5.6

We have released PyPy2.7 v5.6, about two months after PyPy2.7 v5.4. This new PyPy2.7 release includes the upstream stdlib version 2.7.12.

We continue to make incremental improvements to our C-API compatibility layer (cpyext). We pass all but a few of the tests in the upstream numpy test suite.

Work proceeds at a good pace on the PyPy3.5 version due to a grant from the Mozilla Foundation, and some of those changes have been backported to PyPy2.7 where relevant.

The PowerPC and s390x backend have been enhanced with the capability use SIMD instructions
for micronumpy loops.

We changed timeit to now report average +- standard deviation, which is better than the misleading minimum value reported in CPython.

We now support building PyPy with OpenSSL 1.1 in our built-in _ssl module, as well as maintaining support for previous versions.

CFFI has been updated to 1.9, improving an already great package for interfacing with C.

As always, this release fixed many issues and bugs raised by the growing community of PyPy users. We strongly recommend updating.

You can download the PyPy2.7 v5.6 release here:

We would like to thank our donors for the continued support of the PyPy project.

We would also like to thank our contributors and encourage new people to join the project. PyPy has many layers and we need help with all of them: PyPy and RPython documentation improvements, tweaking popular modules to run on pypy, or general help with making RPython’s JIT even better.

What is PyPy?

PyPy is a very compliant Python interpreter, almost a drop-in replacement for CPython 2.7. It’s fast (PyPy and CPython 2.7.x performance comparison) due to its integrated tracing JIT compiler.

We also welcome developers of other dynamic languages to see what RPython can do for them.

This release supports:

  • x86 machines on most common operating systems (Linux 32/64 bits, Mac OS X 64 bits, Windows 32 bits, OpenBSD, FreeBSD)
  • newer ARM hardware (ARMv6 or ARMv7, with VFPv3) running Linux,
  • big- and little-endian variants of PPC64 running Linux,
  • s390x running Linux

Other Highlights (since 5.4 released Aug 31, 2016)

  • New features

    • Allow tests run with -A to find even if it is a script not a dynamically loadable file
    • Backport fixes to rposix on windows from py3.5
    • Allow user-defined __getitem__ on subclasses of str and unicode
    • Add inode to scandir() on posix systems
    • Support more attributes on super
    • Issue #2386: non-latin1 unicode keys were ignored in unicode.format(**d)
    • Restore the ability to translate with CPython
    • Update to CFFI 1.9.0
    • Support the new buffer protocol in cpyext and numpypy
    • Add rposix.sync()
    • Support full-precision nanosecond times in os.stat()
    • Add documentation about the assembler backends to RPYthon
    • Search for the stdlibs from the libpypy shared object rather than the pypy-c exe, changes downstream packaging requirements
    • Add try_inline, like always_inline and dont_inline to RPython
    • Reject 'a'.strip(buffer(' ')) like cpython (the argument to strip must be str or unicode)
    • Allow warning.warn(('something', 1), Warning) like on CPython
    • Refactor rclock and add some more CLOCK_xxx constants on relevant platforms
    • Backport the faulthandler module from py3.5
    • Improve the error message when trying to call a method where the self parameter is missing in the definition
    • Implement rposix.cpu_count
    • Support translation on FreeBSD running on PowerPC
    • Implement __rmod__ on str and unicode types
    • Issue warnings for stricter handling of __new__, __init__ args
    • When using struct.unpack('q', ... try harder to prefer int to long
    • Support OpenSSL version 1.1 (in addition to version 1.0)
  • Bug Fixes

    • Tweak a float comparison with 0 in backendopt.inline to avoid rounding errors
    • Fix translation of the sandbox
    • Fix for an issue where unicode.decode(‘utf8’, ‘custom_replace’) messed up the last byte of a unicode string sometimes
    • fix some calls to functions through window’s COM interface
    • fix minor leak when the C call to socketpair() fails
    • make sure (-1.0 + 0j).__hash__(), (-1.0).__hash__() returns -2
    • Fix for an issue where PyBytesResize was called on a fresh pyobj
    • Fix bug in codewriter about passing the exitswitch variable to a call
    • Don’t crash in merge_if_blocks if the values are symbolics
    • Issue #2325/2361: __class__ assignment between two classes with the same slots
    • Issue #2409: don’t leak the file descriptor when doing open('some-dir')
    • Windows fixes around vmprof
    • Don’t use sprintf() from inside a signal handler
    • Test and fix bug from the guard_not_forced_2 branch, which didn’t save the floating-point register
    • _numpypy.add.reduce returns a scalar now
  • Performance improvements:

    • Improve method calls on oldstyle classes

    • Clean and refactor code for testing cpyext to allow sharing with py3.5

    • Refactor a building the map of reflected ops in _numpypy

    • Improve merging of virtual states in the JIT in order to avoid jumping to the preamble

    • In JIT residual calls, if the called function starts with a fast-path like if != 0: return, then inline the check before doing the


    • Ensure make_inputargs fails properly when given arguments with type information

    • Makes optimiseopt iterative instead of recursive so it can be reasoned about more easily and debugging is faster

    • Refactor and remove dead code from optimizeopt, resume

Please update, and continue to help us make PyPy better.