rqlite /status can be slow to respond with rqlite is under load

[otoolep]

Under load /status can be slow, sometimes too slow for monitoring purposes. I suspect it's the DB layer.

One option could be to wait only for n seconds from DB layer, or examine the queries in the DB layer to determine which might be particularly slow with rqlite is under load.

[mauri870]

Is it strictly required that the stats are always up-to-date upon calling /status? If a small delay is acceptable we could cache this for a couple seconds.

[mauri870]

For the slow queries part, we could instrument the sql.Driver with an interceptor that logs the executed queries with the time spent. That could aid in debugging.

[otoolep]

Actually, I'm thinking about caching some of the stats.

As for your slow query log, yes, that is a feature I'm interested in. Do you have a good, clean, pattern to implement?

[mauri870]

Actually, I'm thinking about caching some of the stats.

As for your slow query log, yes, that is a feature I'm interested in. Do you have a good, clean, pattern to implement?

Caching seems a simple and effective solution for this.

Tracing sql queries is a well requested feature for database/sql(golang/go#18080), but I believe no one is looking into this, there is not even an official proposal yet.

There are third-party libraries that implement this, such as:

• https://github.com/expansiveworlds/instrumentedsql
• https://github.com/shogo82148/go-sql-proxy
• https://github.com/ngrok/sqlmw