Add /-/chaos/gc endpoint to trigger garbage collector (!51579) · Merge requests · GitLab.org / GitLab

Matthias Käppler requested to merge 297489-trigger-gc-endpoint into master Jan 13, 2021

What does this MR do?

For memory measurements, it is often necessary to let memory "settle" to see the impact of a particular change. This requires us to force GC runs so to e.g. tenure objects that are still being referenced. We also hope that this plus the endpoint added to pull system metrics will help to get a more stable baseline for comparisons in performance tests.

Screenshots (strongly suggested)

[10:39:58] work/gl-gck::master ✔ curl -s -XPOST localhost:3000/-/chaos/gc | jq
{
  "worker_id": "puma_1",
  "gc_stat": {
    "count": 94,
    "heap_allocated_pages": 9077,
    "heap_sorted_length": 9077,
    "heap_allocatable_pages": 0,
    "heap_available_slots": 3699720,
    "heap_live_slots": 2827510,
    "heap_free_slots": 872210,
    "heap_final_slots": 0,
    "heap_marked_slots": 2827509,
    "heap_eden_pages": 9077,
    "heap_tomb_pages": 0,
    "total_allocated_pages": 9077,
    "total_freed_pages": 0,
    "total_allocated_objects": 14229357,
    "total_freed_objects": 11401847,
    "malloc_increase_bytes": 8192,
    "malloc_increase_bytes_limit": 30949538,
    "minor_gc_count": 71,
    "major_gc_count": 23,
    "compact_count": 0,
    "remembered_wb_unprotected_objects": 41685,
    "remembered_wb_unprotected_objects_limit": 83370,
    "old_objects": 2617806,
    "old_objects_limit": 5235612,
    "oldmalloc_increase_bytes": 8192,
    "oldmalloc_increase_bytes_limit": 122713697
  }
}