Mercurial > hg-stable
view tests/test-minirst.py @ 26457:7e81305092a0
demandimport: replace more references to _demandmod instances
_demandmod instances may be referenced by multiple importing modules.
Before this patch, the _demandmod instance only maintained a reference
to its first consumer when using the "from X import Y" syntax. This is
because we only created a single _demandmod instance (attached to the
parent X module). If multiple modules A and B performed
"from X import Y", we'd produce a single _demandmod instance
"demandmod" with the following references:
X.Y = <demandmod>
A.Y = <demandmod>
B.Y = <demandmod>
The locals from the first consumer (A) would be stored in <demandmod1>.
When <demandmod1> was loaded, we'd look at the locals for the first
consumer and replace the symbol, if necessary. This resulted in state:
X.Y = <module>
A.Y = <module>
B.Y = <demandmod>
B's reference to Y wasn't updated and was still using the proxy object
because we just didn't record that B had a reference to <demandmod> that
needed updating!
With this patch, we add support for tracking which modules in addition
to the initial importer have a reference to the _demandmod instance and
we replace those references at module load time.
In the case of posix.py, this fixes an issue where the "encoding" module
was being proxied, resulting in hundreds of thousands of
__getattribute__ lookups on the _demandmod instance during dirstate
operations on mozilla-central, speeding up execution by many
milliseconds. There are likely several other operation that benefit from
this change as well.
The new mechanism isn't perfect: references in locals (not globals) may
likely linger. So, if there is an import inside a function and a symbol
from that module is used in a hot loop, we could have unwanted overhead
from proxying through _demandmod. Non-global imports are discouraged
anyway. So hopefully this isn't a big deal in practice. We could
potentially deploy a code checker that bans use of attribute lookups of
function-level-imported modules inside loops.
This deficiency in theory could be avoided by storing the set of globals
and locals dicts to update in the _demandmod instance. However, I tried
this and it didn't work. One reason is that some globals are _demandmod
instances. We could work around this, but it's a bit more work. There
also might be other module import foo at play. The solution as
implemented is better than what we had and IMO is good enough for the
time being.
It's worth noting that this sub-optimal behavior was made worse by the
introduction of absolute_import and its recommended "from . import X"
syntax for importing modules from the "mercurial" package. If we ever
wrote performance tests, measuring the amount of module imports and
__getattribute__ proxy calls through _demandmod instances would be
something I'd have it check.
author | Gregory Szorc <gregory.szorc@gmail.com> |
---|---|
date | Sun, 04 Oct 2015 11:17:43 -0700 |
parents | af9d9b778550 |
children | 67a4e42a651f |
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from pprint import pprint from mercurial import minirst def debugformat(text, form, **kwargs): if form == 'html': print "html format:" out = minirst.format(text, style=form, **kwargs) else: print "%d column format:" % form out = minirst.format(text, width=form, **kwargs) print "-" * 70 if type(out) == tuple: print out[0][:-1] print "-" * 70 pprint(out[1]) else: print out[:-1] print "-" * 70 print def debugformats(title, text, **kwargs): print "== %s ==" % title debugformat(text, 60, **kwargs) debugformat(text, 30, **kwargs) debugformat(text, 'html', **kwargs) paragraphs = """ This is some text in the first paragraph. A small indented paragraph. It is followed by some lines containing random whitespace. \n \n \nThe third and final paragraph. """ debugformats('paragraphs', paragraphs) definitions = """ A Term Definition. The indented lines make up the definition. Another Term Another definition. The final line in the definition determines the indentation, so this will be indented with four spaces. A Nested/Indented Term Definition. """ debugformats('definitions', definitions) literals = r""" The fully minimized form is the most convenient form:: Hello literal world In the partially minimized form a paragraph simply ends with space-double-colon. :: //////////////////////////////////////// long un-wrapped line in a literal block \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\ :: This literal block is started with '::', the so-called expanded form. The paragraph with '::' disappears in the final output. """ debugformats('literals', literals) lists = """ - This is the first list item. Second paragraph in the first list item. - List items need not be separated by a blank line. - And will be rendered without one in any case. We can have indented lists: - This is an indented list item - Another indented list item:: - A literal block in the middle of an indented list. (The above is not a list item since we are in the literal block.) :: Literal block with no indentation (apart from the two spaces added to all literal blocks). 1. This is an enumerated list (first item). 2. Continuing with the second item. (1) foo (2) bar 1) Another 2) List Line blocks are also a form of list: | This is the first line. The line continues here. | This is the second line. """ debugformats('lists', lists) options = """ There is support for simple option lists, but only with long options: -X, --exclude filter an option with a short and long option with an argument -I, --include an option with both a short option and a long option --all Output all. --both Output both (this description is quite long). --long Output all day long. --par This option has two paragraphs in its description. This is the first. This is the second. Blank lines may be omitted between options (as above) or left in (as here). The next paragraph looks like an option list, but lacks the two-space marker after the option. It is treated as a normal paragraph: --foo bar baz """ debugformats('options', options) fields = """ :a: First item. :ab: Second item. Indentation and wrapping is handled automatically. Next list: :small: The larger key below triggers full indentation here. :much too large: This key is big enough to get its own line. """ debugformats('fields', fields) containers = """ Normal output. .. container:: debug Initial debug output. .. container:: verbose Verbose output. .. container:: debug Debug output. """ debugformats('containers (normal)', containers) debugformats('containers (verbose)', containers, keep=['verbose']) debugformats('containers (debug)', containers, keep=['debug']) debugformats('containers (verbose debug)', containers, keep=['verbose', 'debug']) roles = """Please see :hg:`add`.""" debugformats('roles', roles) sections = """ Title ===== Section ------- Subsection '''''''''' Markup: ``foo`` and :hg:`help` ------------------------------ """ debugformats('sections', sections) admonitions = """ .. note:: This is a note - Bullet 1 - Bullet 2 .. warning:: This is a warning Second input line of warning .. danger:: This is danger """ debugformats('admonitions', admonitions) comments = """ Some text. .. A comment .. An indented comment Some indented text. .. Empty comment above """ debugformats('comments', comments) data = [['a', 'b', 'c'], ['1', '2', '3'], ['foo', 'bar', 'baz this list is very very very long man']] rst = minirst.maketable(data, 2, True) table = ''.join(rst) print table debugformats('table', table) data = [['s', 'long', 'line\ngoes on here'], ['', 'xy', 'tried to fix here\n by indenting']] rst = minirst.maketable(data, 1, False) table = ''.join(rst) print table debugformats('table+nl', table)