Author: Armin Rigo <ar...@tunes.org> Branch: Changeset: r76609:295686ab115d Date: 2015-03-28 09:23 +0100 http://bitbucket.org/pypy/pypy/changeset/295686ab115d/
Log: Mention a case of easy-to-fix write-write conflicts diff --git a/pypy/doc/stm.rst b/pypy/doc/stm.rst --- a/pypy/doc/stm.rst +++ b/pypy/doc/stm.rst @@ -409,6 +409,25 @@ This means that ``threadlocalproperty`` is useful mainly to avoid conflicts from cache-like data structures. +* In addition to all of the above, there are cases where write-write + conflicts are caused by writing the same value to an attribute again + and again. See for example ea2e519614ab_: this fixes two such + issues where we write an object field without first checking if we + already did it. The ``dont_change_any_more`` field is a flag set to + ``True`` in that part of the code, but usually this + ``rtyper_makekey()`` method will be called many times for the same + object; the code used to repeatedly set the flag to ``True``, but + now it first checks and only does the write if it is ``False``. + Similarly, in the second half of the checkin, the method + ``setup_block_entry()`` used to both assign the ``concretetype`` + fields and return a list, but its two callers were different: one + would really need the ``concretetype`` fields initialized, whereas + the other would only need to get its result list --- the + ``concretetype`` field in that case might already be set or not, but + that would not matter. + +.. _ea2e519614ab: https://bitbucket.org/pypy/pypy/commits/ea2e519614ab + Note that Python is a complicated language; there are a number of less common cases that may cause conflict (of any kind) where we might not expect it at priori. In many of these cases it could be fixed; please _______________________________________________ pypy-commit mailing list pypy-commit@python.org https://mail.python.org/mailman/listinfo/pypy-commit
