GC

Class methods 23

Instance methods 1

Ruby version changes 10

1. 4.1

   • GC.stat accepts scope: :ractor (the default), scope: :local (a synonym for :ractor), and scope: :global. With the default collector, the global scope reports cumulative collection counts and measured marking/sweeping CPU time across Ractors, including history from destroyed object spaces, without requesting a stop-the-world snapshot. Unscoped GC.stat, GC.count, and GC.total_time retain their current-Ractor behavior.

   • GC.stat reports a new key, :global_gc_count: the number of stop-the-world global garbage collection cycles the current Ractor initiated. Each global collection is attributed to exactly one Ractor, so the values sum across Ractors. GC.stat(:global_gc_count, scope: :global) reports the process total, including the counts of terminated Ractors.

   • A global garbage collection is not counted in :major_gc_count. :count equals :minor_gc_count plus :major_gc_count plus :global_gc_count in both scopes. When another Ractor’s object space exists, including one left by a terminated Ractor that is not yet absorbed, or one was absorbed since the last global collection, GC.start runs a global collection by default, so it increments :global_gc_count rather than :major_gc_count; pass global: false for a local major collection.

   • Global compaction no longer counts overlapping CPU intervals in scalar GC timing statistics. Profiler wall-time intervals are unchanged.

2. 3.4

   • GC.config added to allow setting configuration variables on the Garbage Collector. [Feature #20443]

   • GC configuration parameter rgengc_allow_full_mark introduced. When false GC will only mark young objects. Default is true. [Feature #20443]

3. 3.2

   • Expose need_major_gc via GC.latest_gc_info. GH-6791

4. 3.1

   • “GC.measure_total_time = true” enables the measurement of GC. Measurement can introduce overhead. It is enabled by default. GC.measure_total_time returns the current setting. GC.stat[:time] or GC.stat(:time) returns measured time in milli-seconds. [[Feature #10917]]

   • GC.total_time returns measured time in nano-seconds. [[Feature #10917]]

5. 3.0

   • GC.auto_compact= and GC.auto_compact have been added to control when compaction runs. Setting auto_compact= to true will cause compaction to occur during major collections. At the moment, compaction adds significant overhead to major collections, so please test first! [Feature #17176]