datasette 1.0a29

Simon Willison · Simon Willison · 2026-05-12

Simon Willison releases datasette 1.0a29 with several bug fixes, most notably a race-condition segfault that he diagnosed by using Codex CLI with GPT-5.5 to generate a minimal Dockerfile that reliably reproduced the crash.

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Appears in

OpenAI Codex/GPT-5.5 Emerging as a Real Development Workhorse

Extraction

Topics: datasetteopen-source-developmentai-assisted-debuggingconcurrency

Claims

Datasette 1.0a29 fixes a segfault caused by a race condition between concurrent Datasette.close() calls during tests.
The race condition was introduced when an automatic connection-closing mechanism was added, allowing in-flight queries to execute against already-closed connections.
Codex CLI configured with GPT-5.5 at high compute was used to create a minimal Dockerfile that reproduced the segfault, enabling diagnosis.
Additional fixes in this release include displaying table headers for zero-row tables and correcting a column actions dialog bug on Mobile Safari.

Key quotes

That segfault bug was gnarly.

I ended up solving that by having Codex CLI (with GPT-5.5 xhigh) create a minimal Dockerfile that recreated the bug.