We had a problem where almost all of the threads were waiting on a futex syscall. More specifically:
- `/metrics` handler was inside `TimelineCollector::collect()`, waiting on a mutex for a single Timeline
- This exact timeline was inside `control_file::FileStorage::persist()`, waiting on a mutex for Lazy initialization of `PERSIST_CONTROL_FILE_SECONDS`
- `PERSIST_CONTROL_FILE_SECONDS: Lazy<Histogram>` was blocked on `prometheus::register`
- `prometheus::register` calls `DEFAULT_REGISTRY.write().register()` to take a write lock on Registry and add a new metric
- `DEFAULT_REGISTRY` lock was already taken inside `DEFAULT_REGISTRY.gather()`, which was called by `/metrics` handler to collect all metrics
This commit creates another Registry with a separate lock, to avoid deadlock in a case where `TimelineCollector` triggers registration of new metrics inside default registry.
Part of the general work on improving pageserver logs.
Brief summary of changes:
* Remove `ApiError::from_err`
* Remove `impl From<anyhow::Error> for ApiError`
* Convert `ApiError::{BadRequest, NotFound}` to use `anyhow::Error`
* Note: `NotFound` has more verbose formatting because it's more
likely to have useful information for the receiving "user"
* Explicitly convert from `tokio::task::JoinError`s into
`InternalServerError`s where appropriate
Also note: many of the places where errors were implicitly converted to
500s have now been updated to return a more appropriate error. Some
places where it's not yet possible to distinguish the error types have
been left as 500s.
- Enabled process exporter for storage services
- Changed zenith_proxy prefix to just proxy
- Removed old `monitoring` directory
- Removed common prefix for metrics, now our common metrics have `libmetrics_` prefix, for example `libmetrics_serve_metrics_count`
- Added `test_metrics_normal_work`
