GC.config

This method is implementation-specific to CRuby.

Sets or gets information about the current GC configuration.

Configuration parameters are GC implementation-specific and may change without notice.

With no argument given, returns a hash containing the configuration:

GC.config
# => {rgengc_allow_full_mark: true, implementation: "default"}

With argument hash_to_merge given, merges that hash into the stored configuration hash; ignores unknown hash keys; returns the configuration hash:

GC.config(rgengc_allow_full_mark: false)
# => {rgengc_allow_full_mark: false, implementation: "default"}
GC.config(foo: 'bar')
# => {rgengc_allow_full_mark: false, implementation: "default"}

All-Implementations Configuration

The single read-only entry for all implementations is:

• :implementation: the string name of the implementation; for the Ruby default implementation, 'default'.

Implementation-Specific Configuration

A GC implementation maintains its own implementation-specific configuration.

For Ruby’s default implementation the single entry is:

• :rgengc_allow_full_mark: Controls whether the GC is allowed to run a full mark (young & old objects):

  • true (default): GC interleaves major and minor collections. A flag is set to notify GC that a full mark has been requested. This flag is accessible via GC.latest_gc_info(:need_major_by).

  • false: GC does not initiate a full marking cycle unless explicitly directed by user code; see GC.start. Setting this parameter to false disables young-to-old promotion. For performance reasons, we recommended warming up the application using Process.warmup before setting this parameter to false.