Using the same test as in 7af97c0365,
transmitted wire bytes drops from 135,531 to 133,071 (-1.81%), while
received drops from 21,073 to 14,775 (-30%).
Combined, both changes shave 13,914 bytes (-8.6%) off aggregate
bandwidth usage.
Make it configurable as compression hurts in some scenarios.
For the 52 submodules of ansible.modules.system, this produced a 1602
byte pkg_present list. After stripping it becomes 406 bytes, and the
entire LOAD_MODULE size drops from 1988 bytes to 792 bytes (-60%).
For the 68 submodules of ansible.module_utils, 1902 bytes pkg_present
becomes 474 bytes (-75%), and LOAD_MODULE size drops from 2867 bytes to
1439 bytes (-49%).
In a simple test running Ansible's "setup" module followed by its "apt"
module, wire bytes sent drops from 140,357 to 135,531 (-3.4%).
Turns out it is far too easy to burn through available file descriptors,
so try something else: self-pipes are per thread, and only temporarily
associated with a Lack that wishes to sleep.
Reduce pointless locking by giving Latch its own queue, and removing
Queue.Queue() use in some places.
Temporarily undo merging of of Waker and Latch, let's do this one step
at a time.
Although these are synonyms in Python 2.x, when using MyPy to typecheck
code use of file() causes spurious errors.
This commit also serves as one small step to Python 3.x compatibility,
since 3.x removes the file() builtin.
Now there is a separate SHUTDOWN message that relies only on being
received by the broker thread, the main thread can be hung horribly and
the process will still eventually receive a SIGTERM.
David Wilson