Why this change?
This is a follow up to e8f7b62752.
Tracking of GC stats didn't really belong in the `MethodProfiler` class
so we want to extract that concern into its own class.
As part of this PR, the `track_gc_stat_per_request` site setting has
also been renamed to `instrument_gc_stat_per_request`.
What does this change do?
This change adds a hidden `track_gc_stat_per_request` site setting which
when enabled will track the time spent in GC, major GC count and minor
GC count during a request.
Why is this change needed?
We have plans to tune our GC in production but without any
instrumentation, we will not be able to know if our tuning is effective
or not. This commit takes the first step at instrumenting some basic GC
stats in core during a request which can then be consumed by the discourse-prometheus plugin.
This PR adds MethodProfiler.output_sql_to_stderr! for easier debugging of SQL queries and their timings from the console.
This is almost the same as ensure_discourse_instrumentation! but should not
be used in production (save for debugging in the console), and is only instrumenting
PostgresSQL queries.
This is almost the same as ensure_discourse_instrumentation! but should not
be used in production. This logs all SQL queries run and their durations
between start and stop.
It also works for super long running queries. If you interrupt the long-running
query the latest query data will still be logged after stopping the profiler.
Usage:
```
MethodProfiler.output_sql_to_stderr!(filter_transactions: true)
MethodProfiler.start
# some code that runs queries
timings = MethodProfiler.stop
```
This reduces chances of errors where consumers of strings mutate inputs
and reduces memory usage of the app.
Test suite passes now, but there may be some stuff left, so we will run
a few sites on a branch prior to merging
By default, this does nothing. Two environment variables are available:
- `DISCOURSE_LOG_SIDEKIQ`
Set to `"1"` to enable logging. This will log all completed jobs to `log/rails/sidekiq.log`, along with various db/redis/network statistics. This is useful to track down poorly performing jobs.
- `DISCOURSE_LOG_SIDEKIQ_INTERVAL`
(seconds) Check running jobs periodically, and log their current duration. They will appear in the logs with `status:pending`. This is useful to track down jobs which take a long time, then crash sidekiq before completing.
Detailed request loggers can be used to gather rich timing info
from all requests (which in turn can be forwarded to monitoring solution)
Middleware::RequestTracker.detailed_request_logger(->|env, data| do
# do stuff with env and data
end
