Chunk 30.0

In this chunk, the assistant investigated a crash on the RTX 5090 vast.ai instance (C.32897009) that initially appeared to be an OOM kill. By analyzing the benchmark logs and process state, the assistant discovered that the `cuzk` daemon was a zombie process and the real cause was a bash syntax error in `benchmark.sh` at line 346. The root cause was a complex interaction between `set -euo pipefail`, the `if ! cmd | tee` pipeline pattern, and a bug in the OOM recovery loop where `$?` was incorrectly captured after the `if` statement, always yielding 0 or 1 instead of the actual exit code. The assistant rewrote `benchmark.sh` to use a robust `|| phase_rc=${PIPESTATUS[0]}` pattern, fixed the exit code capture in the retry loop, and removed the redundant daemon start outside the main benchmark function. The fixed script was deployed to the instance via SCP, and a new benchmark run was initiated with `--skip-warmup`. Phase 1 (5 warmup proofs) completed successfully in 518 seconds, demonstrating the script fix worked correctly. However, Phase 2 (the timed run) subsequently failed with a "transport error" / "broken pipe", indicating the daemon crashed again under load. The daemon log showed the system was under extreme memory pressure, exhausting the pinned memory pool. The instance then became unreachable (`Connection refused`), ending the session. Themes in this chunk include the deep debugging required to distinguish between OOM kills and scripting errors, the fragility of complex bash scripts under `pipefail`, and the persistent challenge of operating within tight memory budgets on vast.ai Docker containers. The key achievement was correctly diagnosing and fixing the bash script bugs, while the Phase 2 crash underscored that the fundamental memory pressure issue—operating at 99% of the cgroup limit with insufficient headroom—remains a critical risk for production stability.

The Fix That Revealed the Fire: When a Bash Bug Fix Unmasked a Deeper Memory Crisis 3189 words

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