CloudABI (https://mail.python.org/pipermail/python-dev/2016-July/145708.html) does not provide getpid(). Though this may sound quite silly at first, there is quite a good reason for this. One of the things that CloudABI wants to achieve is making large scale (cluster/cloud) computing easier. In such an environment there is rarely a need for having machine-local unique process identifiers. They have to be globally unique and preferably not recycled.

POSIX requires that pid_t is a signed integer that must have a positive value. Most C compilers only provide full support for integers up to 64 bits in size. This means that CloudABI could only provide 63-bit process identifiers, which is far smaller than, say, a UUID. For this reason we've decided to omit getpid() altogether.

Attached is a patch that makes use of the already existing HAVE_GETPID definition in pyconfig.h to disable the os.getpid() function that is part of the posixmodule.

New changeset d17ff867580f by Berker Peksag in branch '3.6':
Issue #28156: Export os.getpid() conditionally
https://hg.python.org/cpython/rev/d17ff867580f

New changeset 33834105048e by Berker Peksag in branch 'default':
Issue #28156: Merge from 3.6
https://hg.python.org/cpython/rev/33834105048e

Thanks!