Eric Allam
ca399565ba
## Summary Adds direct V8 heap and process-memory gauges to the webapp's OpenTelemetry meter. The webapp already exports per-cluster-worker Node.js runtime metrics (event-loop lag / utilization, active handles, active requests, libuv threadpool size) via a custom meter under the `trigger.dev` scope. Heap and memory were missing; this PR adds them alongside, in the same observable-batch pattern. ## New gauges | Metric | Source | Unit | | --- | --- | --- | | `nodejs.memory.heap.used` | `process.memoryUsage().heapUsed` | bytes | | `nodejs.memory.heap.total` | `process.memoryUsage().heapTotal` | bytes | | `nodejs.memory.heap.limit` | `v8.getHeapStatistics().heap_size_limit` | bytes | | `nodejs.memory.external` | `process.memoryUsage().external` | bytes | | `nodejs.memory.array_buffers` | `process.memoryUsage().arrayBuffers` | bytes | | `nodejs.memory.rss` | `process.memoryUsage().rss` | bytes | Gated by the existing `INTERNAL_OTEL_NODEJS_METRICS_ENABLED` flag, same as the adjacent event-loop / handle gauges. Zero overhead when disabled. ## Why `@opentelemetry/host-metrics` publishes `process.memory.usage`, which is RSS only. RSS is the sum of V8 heap, external memory (Buffers, etc.), native code, and thread stacks. Without a direct heap metric it is not possible to size the V8 heap cap (`--max-old-space-size`) from metrics alone, because RSS overstates heap by the external + native footprint. A worker can have a 4 GB RSS with a 2.5 GB heap and 1.5 GB of buffers; the former constrains `--max-old-space-size`, the latter does not. `nodejs.memory.heap.limit` also surfaces the configured `--max-old-space-size` (read from `v8.getHeapStatistics().heap_size_limit`), so operators can see the current limit in the same dashboard as actual usage rather than cross-referencing container environment variables. ## Risk Minimal. Observable gauges are sampled at the configured metric-export interval. `v8.getHeapStatistics()` and `process.memoryUsage()` are each microsecond-level calls, and six gauges are added to the same batch callback that already reads ~20 other Node.js runtime values per sample. Same registration pattern as the existing event-loop metrics in the file. ## Test plan - [ ] Deploy and confirm the six new gauges appear at the configured exporter - [ ] In cluster mode, confirm per-worker granularity (one series per cluster worker, tagged by `process.executable.name` / `service.instance.id`) - [ ] Confirm `nodejs.memory.heap.limit` reports the configured `--max-old-space-size` value in bytes
Trigger webapp - powered by Remix
To start, run with pnpm run dev --filter webapp
Build the docker image locally:
pnpm run docker:build:webapp
docker run -it triggerdotdev-webapp sh