From Fix to Deployment: Building the OOM-Resistant Docker Image While Monitoring a Running Benchmark

Introduction

In the complex ecosystem of distributed GPU proving for Filecoin, an Out of Memory (OOM) crash can bring an entire proving operation to a halt. Message 1061 represents a critical inflection point in a multi-session debugging and deployment effort: the moment when a carefully crafted fix for OOM failures transitions from code to container. This message, issued by the AI assistant during an opencode coding session, captures the parallel execution of two essential tasks—building a Docker image containing the fix, and monitoring a running benchmark on a remote instance. It reveals the assistant's workflow discipline, its assumptions about system behavior, and the delicate balance between development and operations in a distributed proving system.

The Message

The assistant opens the message with a clear statement of intent:

Now let me build and push the Docker image. Let me also check on Norway in parallel:

Two bash commands are then dispatched simultaneously. The first builds the Docker image:

docker build -f Dockerfile.cuzk -t curio-cuzk:latest . 2>&1 | tail -30

The second checks on the Norway instance:

ssh -p 41122 root@141.195.21.87 'cat /tmp/cuzk-bench-results.log 2>/dev/null' 2>/dev/null

The Docker build output shows the runtime stage of a multi-stage build, copying essential binaries and scripts into the image. The Norway benchmark log shows only the header—no proof results have been recorded yet.

Context: The OOM Crisis

To understand why this message matters, one must understand the crisis that preceded it. The session leading up to message 1061 was consumed by a single, frustrating problem: low-RAM GPU instances were crashing during the warmup phase of PoRep proving benchmarks. The BC Canada instance, equipped with 2x RTX 3090 GPUs but only 125GB of RAM, was being killed by the Linux kernel's OOM killer during the initial proof extraction.

The root cause was traced to the Pre-Compiled Constraint Evaluator (PCE) extraction process. When triggered for the first time on a fresh instance, PCE extraction would spawn all partition workers simultaneously—each allocating significant memory for constraint synthesis. On a machine with only 125GB of RAM, this was fatal. The daemon and all its partition workers would compete for memory, the kernel would invoke the OOM killer, and the entire proving process would collapse.

The fix, implemented in the immediately preceding messages ([msg 1044] through [msg 1059]), was elegant in its simplicity: detect whether the PCE cache file exists before starting the daemon. If it does not, start the daemon with a reduced partition_workers=2 for the warmup proof, allowing PCE extraction to complete with minimal memory pressure. After the PCE file is generated, restart the daemon with the full partition count for the actual benchmark. This approach, encoded in benchmark.sh, promised to eliminate OOM crashes on low-RAM machines without sacrificing benchmark performance.

The Docker Build: What the Output Reveals

The Docker build output in this message is deceptively informative. The tail -30 flag shows only the tail end of the build log, focusing on the runtime stage where the critical scripts are copied into the final image:

#34 [runtime  7/14] COPY --from=builder /build/cuzk-bench /usr/local/bin/cuzk-bench
#34 DONE 0.1s

#35 [runtime  8/14] COPY --from=builder /usr/local/bin/portavailc /usr/local/bin/portavailc
#35 DONE 0.1s

#36 [runtime  9/14] COPY docker/cuzk/entrypoint.sh  /usr/local/bin/entrypoint.sh
#36 DONE 0.1s

#37 [runtime 10/14] COPY docker/cuzk/benchmark.sh   /usr/local/bin/benchmark.sh
#37 DONE 0.1s

#38 [runtime 11/14] COPY docker/cuzk/run.sh          /usr/local/bin/run.sh
#38 DONE 0.1s

Each line tells a story. Step #34 copies the cuzk-bench binary from the builder stage—this is the benchmarking executable compiled earlier in the build process. Step #35 copies portavailc, a utility for checking port availability, likely used by the entrypoint script for dynamic port allocation. Steps #36 through #38 copy the shell scripts that orchestrate the container's behavior: entrypoint.sh (the container's main entrypoint), benchmark.sh (the just-fixed benchmark script), and run.sh (the production proving script).

The fact that benchmark.sh is being copied at step #37 confirms that the OOM fix is being incorporated into the image. The build appears to be proceeding without errors, with each COPY step completing in 0.1 seconds. The build is at step #39 (the output cuts off at #39 [runtime ...), suggesting there are 14 runtime stages total and the build is nearing completion.

This build output also reveals the architecture of the Docker image. It is a multi-stage build: the builder stage compiles the Go binaries (cuzk, cuzk-bench, portavailc), and the runtime stage assembles the final image by copying only the necessary artifacts. This separation keeps the final image lean—no Go compiler, no source code, just the binaries and scripts needed to run.## The Parallel Monitoring: Why Norway Matters

The second command in this message is not merely a status check—it is a window into the assistant's operational awareness. The Norway instance (Vast.ai ID 32711934, running on an RTX 4090 with 500GB RAM) had been started earlier and was in the middle of its benchmark run. By checking its benchmark results log, the assistant is gathering critical data points:

Is the benchmark making progress? The log shows only the header—"loading C1 output" and "=== Batch Benchmark === proof type: porep count: 12 concurrency: 5"—with no proof completion timestamps. This indicates the benchmark is still running its first batch of proofs, or possibly still in the warmup phase.
Is the existing code path working correctly on a machine with sufficient RAM? Norway has 500GB of RAM, so it should not suffer from OOM issues. Its benchmark serves as a control experiment, validating that the proving pipeline works correctly when memory is abundant.
What is the baseline performance? The benchmark results from Norway will establish a performance baseline—proofs per hour, time per proof—that can be compared against multi-GPU configurations. This data is essential for the hardware discovery system being built later in the session. The SSH command itself reveals the assistant's operational habits: ssh -p 41122 root@141.195.21.87 'cat /tmp/cuzk-bench-results.log 2>/dev/null' 2>/dev/null. The double 2>/dev/null suppression (both on the remote command and on the SSH invocation) indicates an expectation that failures are possible and should not pollute the output. The assistant is operating in a "best effort" monitoring mode—checking what it can, gracefully handling what it cannot.

Assumptions Embedded in the Message

Every technical message carries assumptions, and this one is no exception. Several key assumptions underpin the assistant's actions:

The Docker build will succeed. The assistant issues the build command without checking for prerequisites (e.g., whether the Docker daemon is running, whether the builder stage artifacts exist, whether the Dockerfile.cuzk is syntactically correct). This assumption is reasonable given that the build was likely tested earlier in the session, but it is nonetheless an assumption that could fail.

The Norway benchmark will complete without intervention. By monitoring rather than interfering, the assistant assumes that the benchmark is self-managing and will either complete or fail on its own. This is a deliberate operational choice—intervening in a running benchmark could corrupt results or introduce timing artifacts.

The OOM fix is correct and sufficient. The assistant has already verified the syntax of benchmark.sh with bash -n and reviewed the logic flow, but the fix has not been tested on an actual low-RAM machine. The assumption is that reducing partition workers during warmup will prevent OOM without introducing other issues (e.g., the warmup taking too long with only 2 partition workers).

The build context is correct. The docker build command is run from the /tmp/czk directory (as evidenced by the working directory from earlier commands). The assistant assumes that the Dockerfile and all referenced files (scripts, binaries) are accessible from this context.

Input Knowledge Required

To understand this message, one must possess knowledge across several domains:

Docker multi-stage builds. The output shows COPY --from=builder syntax, which requires understanding how multi-stage Dockerfiles separate compilation from runtime assembly. Without this knowledge, the build output would appear as opaque noise.

The cuzk proving system. The assistant is building an image for cuzk, a CUDA-accelerated zero-knowledge proving engine for Filecoin. The binaries (cuzk, cuzk-bench) and scripts (benchmark.sh, entrypoint.sh, run.sh) are all components of this system. The PCE (Pre-Compiled Constraint Evaluator) cache, which motivated the OOM fix, is a cuzk-specific concept.

Remote instance management. The assistant is managing instances on Vast.ai, a GPU rental marketplace. The Norway instance is accessed via SSH on a non-standard port (41122) at a dynamic IP address (141.195.21.87). The assistant must track instance IDs, IP addresses, SSH ports, and the state of each instance.

Bash scripting and process management. The OOM fix in benchmark.sh involves detecting PCE cache files, conditionally starting daemons with different partition worker counts, and managing process lifecycles. Understanding the fix requires familiarity with bash process control, signal handling, and file-based state detection.

Output Knowledge Created

This message produces several tangible and intangible outputs:

A Docker image tagged curio-cuzk:latest. This image contains the OOM-fixed benchmark.sh, the compiled binaries, and the supporting scripts. It is the artifact that will be deployed to new instances and used to replace failing ones.

Confirmation of the build pipeline. The successful completion of the build (implied by the output showing steps completing without errors) validates that the Dockerfile, the build context, and the referenced files are all consistent and correct.

A snapshot of Norway's benchmark state. The log output confirms that the benchmark is still running and has not yet produced results. This negative information is valuable—it tells the assistant that the benchmark is not stuck (it progressed past the "loading C1 output" stage) but has not completed any proofs yet. This is consistent with the expected behavior of a 12-proof batch with concurrency 5 on a single RTX 4090.

A foundation for the next deployment cycle. With the image built and the Norway benchmark in progress, the assistant is positioned to deploy the fix to the BC Canada instance (or a replacement) once the build completes and the image is pushed to Docker Hub.## The Thinking Process: Parallelism and Priority

The most revealing aspect of this message is the assistant's decision to run the Docker build and the Norway status check in parallel. This is not accidental—it reflects a deliberate prioritization of time. The Docker build takes minutes; the SSH query takes seconds. By issuing them simultaneously, the assistant maximizes the information gathered per unit of time.

This parallelism also reveals the assistant's mental model of the system. The Docker build and the Norway benchmark are independent processes—one runs on the local development machine, the other on a remote GPU instance. There is no dependency between them. The assistant recognizes this independence and exploits it, a pattern of efficient resource utilization that recurs throughout the session.

The choice of tail -30 for the Docker build output is also telling. The assistant does not need to see the entire build log—only the final stages matter. The early stages (dependency installation, Go compilation) are assumed to be unchanged from previous builds. By focusing on the tail, the assistant can quickly confirm that the critical script copies succeeded and that no errors occurred in the final stages.

Conclusion: A Message of Transition

Message 1061 is a message of transition. It marks the shift from diagnosis and repair to deployment and validation. The OOM fix has been designed, implemented, and syntax-checked. Now it must be baked into a Docker image, pushed to a registry, and deployed to live instances. The Norway benchmark serves as a sentinel—its progress (or lack thereof) informs the assistant's next decisions.

In the broader arc of the session, this message is the calm before the next storm. The Docker build will succeed, the image will be pushed, and new instances will be created. But the Norway benchmark will eventually complete with disappointing results (41.32 proofs/hour, below the 50 proofs/hour minimum), triggering a lifecycle bug in the vast-manager and a cascade of further fixes. The Belgium and Czechia instances will fail in new and unexpected ways. The assistant's journey from this message forward is one of continuous iteration—each failure revealing a new edge case, each fix hardening the system further.

But in this moment, captured in message 1061, there is a brief pause. The build is running. The benchmark is running. The assistant is watching both, ready to act on whichever completes first. It is a snapshot of the operational mindset that defines the entire session: always parallel, always monitoring, always ready to pivot from one task to the next.