Description

maurycy

opened on Jul 19, 2026

Issue body actions

Bug report

Bug description:

The implicit problem found in https://discuss.python.org/t/tachyon-97-error-rate/107619 and, subsequently, in #151022 and #151036 is that we're raising exceptions and discarding the whole sample, when we could degrade gracefully and keep most of the information.

There are are many limits from which we can recover gracefully, by truncating the data. In particular: funcnames, filenames, locations, but also some temporary reads from the target and other walking limits.

Raising exceptions causes very high error rates, when it doesn't really need to be the case. Also, we really don't know what might be the limits found in the real apps.

CPython versions tested on:

CPython main branch

Operating systems tested on:

macOS

Linked PRs

• gh-154194: Degrade frames in Tachyon instead of failing the sample #154195
• [3.15] gh-154194: Degrade frames in Tachyon instead of failing the sample (GH-154195) #158831
• [3.14] gh-154194: Degrade frames instead of failing the sample (GH-154195) #158833

Reacted by Artem Shumeiko

Activity

1. maurycy

   added

   type-bugAn unexpected behavior, bug, or errorAn unexpected behavior, bug, or error

   on Jul 19, 2026
2. picnixz

   added

   stdlibStandard Library Python modules in the Lib/ directoryStandard Library Python modules in the Lib/ directory

   topic-profiling

   extension-modulesC modules in the Modules dirC modules in the Modules dir

   and removed

   stdlibStandard Library Python modules in the Lib/ directoryStandard Library Python modules in the Lib/ directory

   on Jul 19, 2026
3. pablogsal

   added 5 commits that reference this issue on Oct 5, 2026

   pythongh-154194: Integrate bounded walks and simplify degradation tests

   c6a44a8

   gh-154194: Degrade frames in Tachyon instead of failing the sample (#…

   7d25916

   [3.15] gh-154194: Degrade frames in Tachyon instead of failing the sa…

   c27f494

   [3.14] gh-154194: Degrade frames instead of failing the sample (GH-15…

   4753622

   Revert "[3.15] pythongh-154194: Degrade frames in Tachyon instead of …

   28d4699
4. encukou commented on Oct 6, 2026

   

   encukou

   on Oct 6, 2026

   Member

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   In 3.14, the new tests fail on Intel MacOS: https://buildbot.python.org/#/builders/1729/builds/1721

   Reacted by Maurycy Pawłowski-Wieroński
5. maurycy commented on Oct 6, 2026

   

   maurycy

   on Oct 6, 2026

   ContributorAuthor

   More actions

   @encukou In 3.14, the new tests fail on Intel MacOS: https://buildbot.python.org/#/builders/1729/builds/1721

   @pablogsal My understanding is that this means that #158874 needs a backport to 3.14
6. maurycy commented on Oct 6, 2026

   

   maurycy

   on Oct 6, 2026

   ContributorAuthor

   More actions

   @encukou It's good now https://buildbot.python.org/#/builders/1729/builds/1724 Thank you
7. pablogsal

   closed this as completedon Oct 6, 2026
8. pablogsal

   added a commit that references this issue on Oct 11, 2026

   [3.15] Restore deferred backports for 3.15.1, including GH-158874 (#1…

   4ceb3fa

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