Write-ahead log garbage collection
Kudu maintains a write-ahead log (WAL) per tablet that is split into discrete
fixed-size segments. A tablet periodically rolls the WAL to a new log segment when the active
segment reaches a size threshold (configured by the --log_segment_size_mb
property).
In order to save disk space and decrease startup time, a background task
called LogGCOp
attempts to garbage-collect
(GC) old WAL segments by deleting them from disk once it is determined that they are no longer
needed by the local node for durability.
The metrics associated with this background task have the prefix log_gc
.