Support for Drupal 7 is ending on 5 January 2025—it’s time to migrate to Drupal 10! Learn about the many benefits of Drupal 10 and find migration tools in our resource center.Issue summary update: #2
Beta phase evaluation
| Issue category | Task because it's not a bug, but a potential performance gain, something to be done |
|---|---|
| Issue priority | Normal since it can gain some, but not significant performance gain |
| Disruption | Potentially disruptive(?) for the code that relies on always available DB connection |
Discussed in #2229145: Register symfony session components in the DIC and inject the session service into the request object.
The session manager has a database connection dependency. However on some page requests, it's possible that the only thing that actually happen is on SessionConfiguration::hasSession() which only needs to check a cookie.
This could be a performance hit in the following situation:
1. Database session handler
2. Non-database cache backend
3. Anonymous user gets a page cache miss
4. Everything else that would have triggered a database hit is cached or is hitting some alternative storage
5. This results in a database connection being initialized, even though no actual queries get run.
This is a regression from Drupal 7 where db_query()/db_select() were the main entry points to initializing a db connection.
Proposed resolution
Not sure. The ideal situation for performance would be not initializing the database connection at all until the first real query is run. Then services that inject database + cache and don't need the database if they get a cache hit would also not result in a database connection.
Comments
Comment #1
valthebaldEvaluate the issue during Friday sprints
Comment #2
valthebaldAdded issue summary update, changed priority to Normal
Issue should be postponed according to beta evaluation flowchart