Fix Netmap crash on oversized cache objects#3795
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lunkwill42 merged 2 commits into5.17.xfrom Feb 19, 2026
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Large topology graphs can exceed memcached's default 1MB item size limit, causing `cache.set()` to raise `MemcacheServerError`. This crashed the request even though the data was computed successfully. Wrap all `cache.set()` calls in `_safe_cache_set()` that catches exceptions and logs a warning, returning the response uncached rather than failing with a 500 error.
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Test results 20 files 20 suites 25m 0s ⏱️ Results for commit d9a5c39. |
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Additional details and impacted files@@ Coverage Diff @@
## 5.17.x #3795 +/- ##
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+ Coverage 63.33% 63.38% +0.04%
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Files 619 619
Lines 45875 45882 +7
Branches 43 43
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+ Hits 29057 29083 +26
+ Misses 16808 16789 -19
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johannaengland
approved these changes
Feb 18, 2026
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Scope and purpose
Fixes a production crash where Netmap returns a 500 error when the layer 2 topology graph exceeds memcached's default max item size (1MB). The
MemcacheServerError: b'object too large for cache'exception propagated up fromcache.set()even though the graph data was computed successfully.This pull request
adds/changes/removes a dependencychanges the databasechanges the APIContributor Checklist
Added/changed documentation<major>.<minor>.x). For a new feature or other additions, it should be based onmaster.If applicable: Created new issues if this PR does not fix the issue completely/there is further work to be doneIf this results in changes in the UI: Added screenshots of the before and afterIf this adds a new Python source code file: Added the boilerplate header to that file