Instrument Spanner client (session pool) with OpenCensus metrics #53
Description
Is your feature request related to a problem? Please describe.
Customers run into the Cloud Spanner session pool tuning issues for their specific workload on a regular basis. Improved visibility into the state of the session pool (or client side metrics) maintained by each client can provide actionable insight and help users take informed decisions.
This will also help customers in identifying a session leaks.
Describe the solution you'd like
Instrument Spanner client (session pool) with OpenCensus metrics. we need to capture things including - number of max sessions, number of sessions in use, leaked sessions, count of active spanner requests, count of released and acquired sessions.
Describe alternatives you've considered
N/A
Additional context
N/A
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Edit1: Agreed list of useful metrics:
All the metrics will be prefixed by “cloud.google.com/java/spanner/”.
| Metric | Description | Type | Labels |
|---|---|---|---|
| max_in_use_sessions | The maximum number of sessions in use during the last 10 minute interval | Gauge | database, instance_id, library_version |
| max_allowed_sessions | The maximum number of sessions allowed. Configurable by the user | Gauge | database, instance_id, library_version |
| get_session_timeouts | The number of get sessions timeouts due to pool exhaustion | Counter | database, instance_id, library_version |
| num_acquired_sessions | The number of sessions acquired from the session pool | Counter | database, instance_id, library_version |
| num_released_sessions | The number of sessions released by the user and pool maintainer | Counter | database, instance_id, library_version |
| num_sessions_in_pool | The number of sessions in the pool. | Gauge | database, instance_id, library_version, Type |
- Type : num_in_use_sessions | num_sessions_being_prepared | num_read_sessions | num_write_prepared_sessions
/cc @skuruppu