SG-43269 Fix sys.path and sys.meta_path isolation during core swap#1101
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SG-43269 Fix sys.path and sys.meta_path isolation during core swap#1101julien-lang wants to merge 1 commit into
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When the site core (e.g. v0.23.8 bundled with SGD 3.0) boots, its tank_vendor/__init__.py inserts its pkgs.zip into sys.path[0] and registers a _TankVendorMetaFinder in sys.meta_path. Previously, _swap_core() cleaned up sys.modules but left both of those in place. This caused two distinct failures when swapping to an older project core: 1. sys.path pollution: direct imports like Version: ImageMagick 7.1.2-23 Q16-HDRI aarch64 6c51b2de5:20260516 https://imagemagick.org By default, 'file' is written in the MIFF image format. To specify a particular image format, precede the filename with an image format name and a colon (i.e. ps:image) or specify the image type as the filename suffix (i.e. image.ps). Specify 'file' as '-' for standard input or output. (not via tank_vendor.*) resolved to the site core's pkgs.zip instead of the project core's vendored copy. The site pkgs.zip lacks packages removed in newer releases (e.g. sgsix), causing ImportError. 2. Stale _TankVendorMetaFinder: when six.__path__ == [] caused CoreImportHandler to return None for , the stale meta finder intercepted the import and tried to resolve it against the old sys.path state (site pkgs.zip, no six), causing ModuleNotFoundError. Fix: in _swap_core(), before resetting self._core_path: - Strip all sys.path entries that live under the outgoing core root. - Remove any _TankVendorMetaFinder instances from sys.meta_path and delete sys._tank_vendor_meta_finder. The incoming core's tank_vendor/__init__.py will then insert its own pkgs.zip and register a fresh finder when Version: ImageMagick 7.1.2-23 Q16-HDRI aarch64 6c51b2de5:20260516 https://imagemagick.org By default, 'file' is written in the MIFF image format. To specify a particular image format, precede the filename with an image format name and a colon (i.e. ps:image) or specify the image type as the filename suffix (i.e. image.ps). Specify 'file' as '-' for standard input or output. loads it. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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| norm_p = os.path.normpath(p) | ||
| try: | ||
| if os.path.commonpath([norm_p, current_core_root]) == current_core_root: | ||
| log.debug("Removing sys.path entry belonging to outgoing core: %s" % p) |
Codecov Report✅ All modified and coverable lines are covered by tests. Additional details and impacted files@@ Coverage Diff @@
## master #1101 +/- ##
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+ Coverage 79.45% 79.46% +0.01%
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Files 198 198
Lines 20769 20785 +16
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+ Hits 16502 16517 +15
- Misses 4267 4268 +1
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What
Fixes a
sys.pathandsys.meta_pathisolation bug in_swap_core()that caused project bootstrapping to fail when the site core is newer (pkgs.zip-style, e.g. v0.23.8) and the project core is older (vendored-style, e.g. v0.22.4).Two things are now cleaned up in
_swap_core()before handing off to the incoming core:sys.pathcleanup — removes all entries that live under the outgoing core's root directory. This ensures the site core'spkgs.zipis no longer onsys.pathwhen the project core loads, so direct imports likeimport shotgun_api3resolve to the project core's vendored copy rather than the site's.sys.meta_pathcleanup — removes the stale_TankVendorMetaFinderinstance registered by the outgoing core'stank_vendor/__init__.py. The incoming core'stank_vendor/__init__.pyinstalls a fresh one whenimport tankloads it.Why
Two distinct customer-facing failures traced to the same root cause:
SGD 3.0 + project config ≤ v1.7.5 →
ModuleNotFoundError: No module named 'tank_vendor.six.moves'tank_vendor/__init__.pyinserts itspkgs.zipatsys.path[0]and registers_TankVendorMetaFinderinsys.meta_path._swap_core()runs → stashessys.modulesentries but leavessys.pathandsys.meta_pathuntouched.six.pyas a plain file;six.__path__ == []. Whentank_vendor.six.movesis requested,CoreImportHandler.find_specreturnsNone(emptypackage_path), and the stale_TankVendorMetaFinderintercepts the import — but the sitepkgs.ziphas nosix, so it fails.Flame 2025.1 + project config ≤ v1.10.20 →
ImportError: cannot import name 'sgsix' from 'shotgun_api3.lib'pkgs.zipis still atsys.path[0].shotgun_api3is not inNAMESPACES_TO_TRACK, soCoreImportHandlerignores it.PathFinderresolvesshotgun_api3from the sitepkgs.zip, which has a newer version withoutsgsix. Project code that expectssgsixfails.Changes
python/tank/bootstrap/import_handler.py—_swap_core(): strip outgoing-coresys.pathentries and remove stale_TankVendorMetaFinderbefore resettingself._core_path.Related
Closes / supersedes the diagnostic-only approach in #1099.