Experimental and env-gated (defaults off — stock behavior unchanged).
Read path is made fully non-blocking on both sides so neither the worker
nor the server waits on the stage behind it:
Postgres -> [server-side buffer] -> HTTP -> [agent-side buffer] -> worker
- batch pull/complete: N jobs per pull, N completions per flush, so the
per-job HTTP round-trips and per-job dequeue queries are amortized
- server-side prefetch: a single background puller per job-tag-set runs
the SKIP LOCKED dequeue ahead of demand and coalesces concurrent agents,
moving the PG query off the request critical path
- agent-side prefetch: a background refiller keeps the local job buffer
deep (high low-watermark + several refills in flight) so the worker
loop pops without a network call
- empty-pull backoff fix: don't apply the idle long-sleep to a transient
empty pull from a prefetching consumer
- AGENT_PROF: per-phase profiler + auto-rendered per-job time-budget SVG
Single agent goes from ~2.5k to ~125k+ j/s. Multi-agent collapse is
reproduced but its root cause is still open (not established to be PG).
See benchmarks/agent_worker_scaling.md.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Earlier README told users to run a second `kubectl port-forward` and
hard-coded port 33405. Both wrong: wm_sim up calls portForwardApi() in
helm_deploy.ts:213, picks a free local port, prints `[helm] API reachable
at http://127.0.0.1:<port>`, and keeps the forward alive as a child of
the wm_sim process.
Updated workflow: read the URL out of wm_sim's output, pass it to main.ts
as --host. Kept a note about restarting the forward manually when the
kubelet drops it under heavy bench load (real failure mode we hit).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
sim/README.md was last touched May 27 and described the pre-minikube
docker/podman-based "three node modes" design with k8s mode listed as
"planned for M5". The reality is now k8s-only via minikube + helm, and
the workflow / config-files / outputs all changed.
New sim/README.md covers:
- The actual `wm_sim up` CLI form against the external
windmill-helm-charts chart and smoke.yaml / local.yaml overlays.
- Two-shell workflow: wm_sim up in one, port-forward + main.ts in the
other, report at reports/<timestamp>/dashboard.svg.
- Measurement subsystem table: per-pod CPU/mem sampler DS, JSONL pollers
(pod_timeline, oom, pg_latency, pg_conn, node_load), throughput
capture, failed-jobs fetch, pgBadger.
- The three reliability fixes we leaned on this session and why they
matter: sampler host-log file (kubelet log rotation), readiness
rollout-complete check (cgroup_mutex starvation), procs_running for
oversaturation (not load1 / D-state overcount).
- Dashboard panel index + the shared bench_start_ms x-axis origin.
- Workload catalog (io_4phase + flood variants + ops_day + cpu).
- Agent worker setup with the Secret-based JWT.
- Test entry points (util_metrics_test, util_panel_snapshot_test).
- Operational notes (port-forward fragility, minikube stop safety).
- File-by-file code layout under sim/.
benchmarks/README.md gains a "Cluster benchmarks — sim mode" section
linking to sim/README.md plus a quick-start snippet so the path from
the legacy benchmark suite docs into the cluster workflow is obvious.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Stand up a minikube-backed simulation subsystem for benching Windmill under
realistic multi-node load, with a per-bench measurement pipeline and a
dashboard renderer that consolidates throughput, queue depth, per-node CPU,
PG latency/conns, OOM events, and per-node CPU-util-vs-oversaturation into
one SVG report.
Sim infrastructure (sim/):
- k8s_provisioner: minikube up + heterogeneous node sizing from topology JSON
- helm_deploy: helm install Windmill with smoke.yaml + local.yaml overlays
- image_cache: pre-load required images so bench bringup is offline-safe
- toxiproxy_k8s: per-node toxiproxy DaemonSet for cross-node latency injection
- cpu_sampler_k8s: privileged DS reading per-cgroup cpu.stat at 10Hz, dual-
writes to stdout AND a host-mounted log file (/var/log/wm-sim-cpu-sampler/
sampler.tsv) so heavy benches no longer lose early samples to kubelet log
rotation
- pg_logging: ALTER SYSTEM + SIGHUP to enable verbose PG logging without restart
- pgbadger: post-bench PG log analysis HTML report
- readiness: pre-bench cluster health check (samplers stable ≥30s, workers
ready, PG responsive, queue empty, **deploy.status rollout-complete**) —
the rollout-complete check catches mid-rolling-update fires that previously
starved m04's sampler under cgroup_mutex contention
Per-bench JSONL pollers, started/finalized alongside the bench loop:
- pod_timeline: 1Hz workers-per-node Ready counts (used for the workers panel)
- oom_poller: live OOM event capture (kernel + kubelet evictions + cgroup)
- pg_latency_poller: 4Hz psql \\timing on SELECT 1 vs kubectl-exec roundtrip
- pg_conn_poller: 1Hz pg_stat_activity by state (active/idle/idle_in_xact)
- node_load_poller: 2Hz /proc/loadavg + /proc/stat procs_running per node
Dashboard renderer (sim/render_report.ts + graph.ts):
- Util group: one panel per node with translucent orange oversaturation area
BEHIND solid blue CPU-util area, 100% reference line, phase-boundary verticals.
cols:2 grid wraps after 2 panels per row.
- PG node tinted with [PG] flag in legend across the dashboard.
- Phase-boundary verticals + push-window shaded zones layered consistently.
- All x-axes switched from wall-clock HH:MM to relative seconds-from-bench-
start. Shared origin sourced from meta.json's bench_start_ms so 0s on every
panel = the same wall-clock moment (previously each chart picked its own
earliest sample as origin, causing drift between panels).
Oversaturation metric, with explicit fallback:
- Primary: (procs_running - ncpu) / ncpu × 100 — true CPU run-queue pressure.
- Fallback to load1 when procs_running is missing (older reports).
- load1 overcounted previously because it includes uninterruptible D-state
procs (PG backends in disk I/O, cgroup_mutex waits), inflating "saturation"
by 5-10x under load.
- Pure helper extracted to sim/util_metrics.ts; 8 unit tests cover the
procs_running > load1 preference, the clamp-at-zero, invalid-ncpu cases.
Sampler reliability:
- HostPath log file in addition to stdout so the bench's scp-based collector
bypasses kubelet log rotation entirely.
- main.ts truncates the host log file on every node before pushers start
(parallel ssh, best-effort) so it doesn't grow unbounded across runs.
- Collector falls back to kubectl-logs when scp fails for any node.
Workloads (workloads/):
- io_4phase: four-phase IO step (idle → 2.5s → 500ms → 150ms jobs)
- io_150ms_flood / io_300ms_flood / io_1s_flood / io_2s_flood: single-phase
flood configs to isolate the worker-host CFS context-switch storm vs PG
contention regime
- burst, ops_day, cpu_*, etc. for other scenarios
Tests:
- sim/util_metrics_test.ts — 8 cases for computeOversatPct
- sim/util_panel_snapshot_test.ts — 5 assertions guarding util-panel SVG
invariants (orange behind blue, 100% ref line, relative-time ticks NOT
wall-clock, phase-boundary verticals, shared-origin override)
Helm values:
- sim/values/smoke.yaml — bench-tuned: workers w/ no CPU limit & low mem
request, PG w/ 3-core request + wm-critical priorityClass + oomImmune +
maxConnections, app w/ wm-critical + oomImmune + no resource limits.
- sim/values/local.example.yaml — template for the gitignored local.yaml
that carries the EE license key.
- Depends on the wm-critical PriorityClass + oomImmune + maxConnections
knobs landing in windmill-helm-charts (separate PR).
graph.ts additions:
- areaFills param: ordered list of per-kind translucent area fills drawn
before lines, used by the util panel for orange-behind-blue layering
- lineColorOverrides: pin per-kind line colors so oversaturation reliably
renders orange regardless of d3 ordinal-color insertion order
- highlightKindToken: substring-match flag for the PG-node tint in Node CPU
- xRelativeOriginMs: shared bench-start origin for the relative-time x-axis
- DataPointMulti is now exported for downstream tests
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
pyranota
Pyra
Ruben Fiszel