Where is documentation for multiprocessing.pool.ApplyResult?

python python-2.x python-2.6 python-multiprocessing
Mark Gerolimatos picture Mark Gerolimatos · Nov 23, 2016 · Viewed 8.4k times · Source

There is frighteningly little strict API documentation (read: ZERO) for multiprocessing.pool.ApplyResult. The multiprocessing explanation doc talks about ApplyResults, but does not define them.

The same appears to apply to multiprocessing.pool.Pool, although the Python multiprocessing guide appears to cover it better.

Even the ApplyResult help() results are paltry:

 |  get(self, timeout=None)
 |  
 |  ready(self)
 |  
 |  successful(self)
 |  
 |  wait(self, timeout=None)

  • Get() and Ready() I get. Those are fine.

  • I have absolutely no idea what wait() is for, given that you are dealing with a "pool", which one would assume would waits for you in the get() call. Is this "wait for the result, but don't get it now" Or is it an OS-style wait? And if so, what would that even mean?

  • I am equally unsure of what successful() is all about.

Answer

BrenBarn picture BrenBarn · Nov 23, 2016

You're right that there is in a glitch in the documentation: the class is actually documented as AsyncResult, not ApplyResult. The two are different names for the same class:

>>> multiprocessing.pool.ApplyResult is multiprocessing.pool.AsyncResult
True

The name may have been changed at some point and the docs weren't consistently updated, but everything is documented, it's just documented under the wrong name. (There is a closed bug in which someone pointed out that the docs mention AsyncResult but the class is actually called ApplyResult, so they added AsyncResult as an alias.)

Related questions

Alternative to dict comprehension prior to Python 2.7

How can I make the following functionality compatible with versions of Python earlier than Python 2.7? gwfuncs = [reboot, flush_macs, flush_cache, new_gw, revert_gw, send_log] gw_func_dict = {chr(2**i): func for i, func in enumerate(gwfuncs[:8])}

Read More
UnicodeEncodeError: 'ascii' codec can't encode character u'\xa0' in position 20: ordinal not in range(128)

I'm having problems dealing with unicode characters from text fetched from different web pages (on different sites). I am using BeautifulSoup. The problem is that the error is not always reproducible; it sometimes works with some pages, and sometimes, it …

Read More
How to return dictionary keys as a list in Python?

In Python 2.7, I could get dictionary keys, values, or items as a list: >>> newdict = {1:0, 2:0, 3:0} >>> newdict.keys() [1, 2, 3] Now, in Python >= 3.3, I get something like this: >>> newdict.keys() dict_keys([1, 2, 3]) So, I …

Read More