gh-116738: Make cmath module thread-safe - #142161
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colesbury
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colesbury
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Generally looks good. It's subinterpreter specific and not really free threading related (i.e., you'll have the same data races with the default GIL enabled build).
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Looks good, but could you double check and verify that all functions include tests for all combinations of special values? I.e. when one component is a zero, infinity or nan, same other (or is a finite nonzero number, if the first is nonzero).
Tests are here: Lib/test/mathdata/cmath_testcases.txt (usually in a dedicated section, like "special values").
Test script
#!/bin/sh
# a.sh
file=Lib/test/mathdata/cmath_testcases.txt
funcs="acos acosh asinh atanh cosh exp log sinh sqrt tanh rect"
zeros="0.0 -0.0"
nonfinite="-inf nan inf"
all="$zeros $nonfinite [1-9]\.[0-9].* -[1-9]\.[0-9].*"
for f in $funcs
do
for t1 in $zeros
do
for t2 in $zeros $nonfinite
do
re=" $f $t1 $t2 -> "
grep -q "$re" $file || echo "$f $t1 $t2 - missing"
re=" $f $t2 $t1 -> "
grep -q "$re" $file || echo "$f $t2 $t1 - missing"
done
done
for t1 in $nonfinite
do
for t2 in $all
do
re=" $f $t1 $t2 -> "
grep -q "$re" $file || echo "$f $t1 $t2 - missing!"
re=" $f $t2 $t1 -> "
grep -q "$re" $file || echo "$f $t2 $t1 - missing!"
done
done
done
skirpichev
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skirpichev
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LGTM
I've checked that special values are tested, though appreciate a second look. Please adjust PR description (an maybe title).
Thank you so much, @skirpichev I’ve checked them as well and they look good to me. I am just sharing how I verified this locally, since it’s easy to accidentally copy-paste something incorrectly and not notice it: I compared the statically initialized version with the previous version before deleting the old tables from the code. |
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🤖 New build scheduled with the buildbot fleet by @colesbury for commit 64254ba 🤖 Results will be shown at: https://buildbot.python.org/all/#/grid?branch=refs%2Fpull%2F142161%2Fmerge If you want to schedule another build, you need to add the 🔨 test-with-buildbots label again. |
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Thanks @yoney for the PR, and @colesbury for merging it 🌮🎉.. I'm working now to backport this PR to: 3.14. |
…ule (pythongh-142161) The initialization during `mod_exec` wasn't thread-safe with multiple interpreters. (cherry picked from commit 2dac9e6) Co-authored-by: Alper <alperyoney@fb.com>
…ule (pythongh-142161) The initialization during `mod_exec` wasn't thread-safe with multiple interpreters.
5 participants
While investigating thread safety in the
cmathmodule, I found that the module is generally thread-safe. However, there is a potential race condition during the initialization of the special value tables incmath_exec(). This is usually safe, but with subinterpreters, a race condition could occur.The fix converts all special value tables from runtime initialization to static initialization, eliminating the race condition.
I have also created a test to run under ThreadSanitizer. However, I am not including the test in the current PR because, although this PR addresses the issue in the
cmathmodule, ThreadSanitizer still reports other issues below when subinterpreters and free-threading are used together. I plan to address those issues.cc: @mpage @colesbury