https://nalar.dev/tags/warnings/ Recent content in Warnings on Nalar Hugo en-us Wed, 09 Sep 2026 00:00:00 +0700 https://nalar.dev/make-warning-tests-concurrency-safe-with-context-aware-warnings/ Wed, 09 Sep 2026 00:00:00 +0700 https://nalar.dev/make-warning-tests-concurrency-safe-with-context-aware-warnings/ <p>Python&rsquo;s <code>warnings.catch_warnings()</code> is convenient in tests, compatibility shims, and small diagnostic scopes. It lets code temporarily change warning filters and then restore the previous state.</p> <p>That model becomes harder to reason about when several threads or asynchronous tasks use it at the same time. Historically, <code>catch_warnings()</code> manipulated process-global state in the <code>warnings</code> module. Two overlapping contexts could therefore interfere with each other.</p> <p>Python 3.14 adds an opt-in context-aware mode that changes this behavior. When <code>sys.flags.context_aware_warnings</code> is true, <code>catch_warnings()</code> stores its filtering state in a context variable instead of mutating the same global warning state for every concurrent execution path.</p>