This roughly follows what was done for dictobject to make a lock-free
lookup operation. With this change, the set contains operation scales much
better when used from multiple-threads. The frozenset contains performance
seems unchanged (as already lock-free).
Summary of changes:
* refactor set_lookkey() into set_do_lookup() which now takes a function
pointer that does the entry comparison. This is similar to dictobject and
do_lookup(). In an optimized build, the comparison function is inlined and
there should be no performance cost to this.
* change set_do_lookup() to return a status separately from the entry value
* add set_compare_frozenset() and use if the object is a frozenset. For the
free-threaded build, this avoids some overhead (locking, atomic operations,
incref/decref on key)
* use FT_ATOMIC_* macros as needed for atomic loads and stores
* use a deferred free on the set table array, if shared (only on free-threaded
build, normal build always does an immediate free)
* for free-threaded build, use explicit for loop to zero the table, rather than memcpy()
* when mutating the set, assign so->table to NULL while the change is a
happening. Assign the real table array after the change is done.
Makes the zlib module thread-safe free-threading build. Even though operations
are protected by locks, attributes exposed via PyMemberDef (eof, needs_input,
unused_data, unconsumed_tail) should still be stored atomically within locked
sections, since they can be read without acquiring the lock.
If there are many untracked tuples, the GC will run too often, resulting
in poor performance. The fix is to include untracked tuples in the
"long lived" object count. The number of frozen objects is also now
included since the free-threaded GC must scan those too.
* Pick target depending on preconditions
* Clarify the news fragment
* Add test capturing missed expectation.
* Add more idiomatic safe realpath helper
* Restore logic where existance and directoriness are checked on realpath.
* Link GH issue to test.
* Extract a function to check the target. Remove the _safe_realpath, now no longer needed.
* Extract method for replacing sys_path, and isolate realpath usage there.
* Revert "Extract method for replacing sys_path, and isolate realpath usage there."
This reverts commit 855aac3d28.
* Restore _safe_realpath.
---------
Co-authored-by: Jason R. Coombs <jaraco@jaraco.com>
For optional arguments with required=True, the ArgumentDefaultsHelpFormatter
would always add a " (default: None)" to the end of the help text.
Since that's a bit misleading, it is removed with this commit.
