Render cache memory usage grows continuously during sustained page rendering

Symptom

Under sustained page rendering, Drupal's render cache consumes increasing memory, eventually exhausting the PHP memory limit.

Goal

Determine whether to enable automatic garbage collection of orphaned cache tags in the database cache backend to keep the cache_tags table bounded after the render cache memory leak fix.

Considerations

The fix prevents new leaks but does not automatically remove existing orphaned tags; administrators must decide on a cleanup schedule or enable automatic GC, weighing potential performance overhead against storage growth.

• Should automatic garbage collection of orphaned cache tags be enabled by default on sites using the database cache backend?
• What performance impact does periodic tag cleanup have on request processing and background cron?
• How frequently should the cleanup run to balance table size growth with resource usage?