bpo-42398: Fix "make regen-all" race condition #23362
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Fix a race condition in "make regen-all" when make -jN option is used to run jobs in parallel. The clinic.py script now only use atomic write to write files. Moveover, generated files are now left unchanged if the content does not change, to not change the file modification time. The "make regen-all" command runs "make clinic" and "make regen-importlib" targets: * "make regen-importlib" builds object files (ex: Modules/_weakref.o) from source files (ex: Modules/_weakref.c) and clinic files (ex: Modules/clinic/_weakref.c.h) * "make clinic" always rewrites all clinic files (ex: Modules/clinic/_weakref.c.h) Since there is no dependency between "clinic" and "regen-importlib" Makefile targets, these two targets can be run in parallel. Moreover, half of clinic.py file writes are not atomic and so there is a race condition when "make regen-all" runs jobs in parallel using make -jN option (which can be passed in MAKEFLAGS environment variable). Fix clinic.py to make all file writes atomic: * Add write_file() function to ensure that all file writes are atomic: write into a temporary file and then use os.replace(). * Moreover, write_file() doesn't recreate or modify the file if the content does not change to avoid modifying the file modification file. * Update test_clinic to verify these assertions with a functional test. * Remove Clinic.force attribute which was no longer used, whereas Clinic.verify remains useful.
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Thanks @vstinner for the PR 🌮🎉.. I'm working now to backport this PR to: 3.9. |
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Sorry, @vstinner, I could not cleanly backport this to |
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GH-23367 is a backport of this pull request to the 3.9 branch. |
vstinner
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Nov 18, 2020
Fix a race condition in "make regen-all" when make -jN option is used to run jobs in parallel. The clinic.py script now only use atomic write to write files. Moveover, generated files are now left unchanged if the content does not change, to not change the file modification time. The "make regen-all" command runs "make clinic" and "make regen-importlib" targets: * "make regen-importlib" builds object files (ex: Modules/_weakref.o) from source files (ex: Modules/_weakref.c) and clinic files (ex: Modules/clinic/_weakref.c.h) * "make clinic" always rewrites all clinic files (ex: Modules/clinic/_weakref.c.h) Since there is no dependency between "clinic" and "regen-importlib" Makefile targets, these two targets can be run in parallel. Moreover, half of clinic.py file writes are not atomic and so there is a race condition when "make regen-all" runs jobs in parallel using make -jN option (which can be passed in MAKEFLAGS environment variable). Fix clinic.py to make all file writes atomic: * Add write_file() function to ensure that all file writes are atomic: write into a temporary file and then use os.replace(). * Moreover, write_file() doesn't recreate or modify the file if the content does not change to avoid modifying the file modification file. * Update test_clinic to verify these assertions with a functional test. * Remove Clinic.force attribute which was no longer used, whereas Clinic.verify remains useful. (cherry picked from commit 8fba952)
miss-islington
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Nov 18, 2020
…onGH-23367) Fix a race condition in "make regen-all" when make -jN option is used to run jobs in parallel. The clinic.py script now only use atomic write to write files. Moveover, generated files are now left unchanged if the content does not change, to not change the file modification time. The "make regen-all" command runs "make clinic" and "make regen-importlib" targets: * "make regen-importlib" builds object files (ex: Modules/_weakref.o) from source files (ex: Modules/_weakref.c) and clinic files (ex: Modules/clinic/_weakref.c.h) * "make clinic" always rewrites all clinic files (ex: Modules/clinic/_weakref.c.h) Since there is no dependency between "clinic" and "regen-importlib" Makefile targets, these two targets can be run in parallel. Moreover, half of clinic.py file writes are not atomic and so there is a race condition when "make regen-all" runs jobs in parallel using make -jN option (which can be passed in MAKEFLAGS environment variable). Fix clinic.py to make all file writes atomic: * Add write_file() function to ensure that all file writes are atomic: write into a temporary file and then use os.replace(). * Moreover, write_file() doesn't recreate or modify the file if the content does not change to avoid modifying the file modification file. * Update test_clinic to verify these assertions with a functional test. * Remove Clinic.force attribute which was no longer used, whereas Clinic.verify remains useful. (cherry picked from commit 8fba952) (cherry picked from commit c53c3f4) Co-authored-by: Victor Stinner <vstinner@python.org>
miss-islington
added a commit
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Nov 18, 2020
Fix a race condition in "make regen-all" when make -jN option is used to run jobs in parallel. The clinic.py script now only use atomic write to write files. Moveover, generated files are now left unchanged if the content does not change, to not change the file modification time. The "make regen-all" command runs "make clinic" and "make regen-importlib" targets: * "make regen-importlib" builds object files (ex: Modules/_weakref.o) from source files (ex: Modules/_weakref.c) and clinic files (ex: Modules/clinic/_weakref.c.h) * "make clinic" always rewrites all clinic files (ex: Modules/clinic/_weakref.c.h) Since there is no dependency between "clinic" and "regen-importlib" Makefile targets, these two targets can be run in parallel. Moreover, half of clinic.py file writes are not atomic and so there is a race condition when "make regen-all" runs jobs in parallel using make -jN option (which can be passed in MAKEFLAGS environment variable). Fix clinic.py to make all file writes atomic: * Add write_file() function to ensure that all file writes are atomic: write into a temporary file and then use os.replace(). * Moreover, write_file() doesn't recreate or modify the file if the content does not change to avoid modifying the file modification file. * Update test_clinic to verify these assertions with a functional test. * Remove Clinic.force attribute which was no longer used, whereas Clinic.verify remains useful. (cherry picked from commit 8fba952) (cherry picked from commit c53c3f4) Co-authored-by: Victor Stinner <vstinner@python.org>
adorilson
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Mar 13, 2021
Fix a race condition in "make regen-all" when make -jN option is used to run jobs in parallel. The clinic.py script now only use atomic write to write files. Moveover, generated files are now left unchanged if the content does not change, to not change the file modification time. The "make regen-all" command runs "make clinic" and "make regen-importlib" targets: * "make regen-importlib" builds object files (ex: Modules/_weakref.o) from source files (ex: Modules/_weakref.c) and clinic files (ex: Modules/clinic/_weakref.c.h) * "make clinic" always rewrites all clinic files (ex: Modules/clinic/_weakref.c.h) Since there is no dependency between "clinic" and "regen-importlib" Makefile targets, these two targets can be run in parallel. Moreover, half of clinic.py file writes are not atomic and so there is a race condition when "make regen-all" runs jobs in parallel using make -jN option (which can be passed in MAKEFLAGS environment variable). Fix clinic.py to make all file writes atomic: * Add write_file() function to ensure that all file writes are atomic: write into a temporary file and then use os.replace(). * Moreover, write_file() doesn't recreate or modify the file if the content does not change to avoid modifying the file modification file. * Update test_clinic to verify these assertions with a functional test. * Remove Clinic.force attribute which was no longer used, whereas Clinic.verify remains useful.
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Fix a race condition in "make regen-all" when make -jN option is used
to run jobs in parallel. The clinic.py script now only use atomic
write to write files. Moveover, generated files are now left
unchanged if the content does not change, to not change the file
modification time.
The "make regen-all" command runs "make clinic" and "make
regen-importlib" targets:
from source files (ex: Modules/_weakref.c) and clinic files (ex:
Modules/clinic/_weakref.c.h)
(ex: Modules/clinic/_weakref.c.h)
Since there is no dependency between "clinic" and "regen-importlib"
Makefile targets, these two targets can be run in parallel. Moreover,
half of clinic.py file writes are not atomic and so there is a race
condition when "make regen-all" runs jobs in parallel using make -jN
option (which can be passed in MAKEFLAGS environment variable).
Fix clinic.py to make all file writes atomic:
atomic: write into a temporary file and then use os.replace().
content does not change to avoid modifying the file modification
file.
test.
Clinic.verify remains useful.
https://bugs.python.org/issue42398