Function: SB-INTROSPECT:ALLOCATION-INFORMATION

Returns information about the allocation of OBJECT. Primary return value indicates the general type of allocation: :IMMEDIATE, :HEAP, :STACK, or :FOREIGN.

Possible secondary return value provides additional information about the allocation.

For :HEAP objects the secondary value is a plist:

:SPACE Indicates the heap segment the object is allocated in.

:GENERATION Is the current generation of the object: 0 for nursery, 6 for pseudo-static generation loaded from core. (GENCGC and :SPACE :DYNAMIC only.)

:LARGE Indicates a “large” object subject to non-copying promotion. (GENCGC and :SPACE :DYNAMIC only.)

:BOXED Indicates that the object is allocated in a boxed region. Unboxed allocation is used for eg. specialized arrays after they have survived one collection. (GENCGC and :SPACE :DYNAMIC only.)

:PINNED Indicates that the page(s) on which the object resides are kept live due to conservative references. Note that object may reside on a pinned page even if :PINNED in NIL if the GC has not had the need to mark the the page as pinned. (GENCGC and :SPACE :DYNAMIC only.)

:WRITE-PROTECTED Indicates that the page on which the object starts is write-protected, which indicates for :BOXED objects that it hasn’t been written to since the last GC of its generation. (GENCGC and :SPACE :DYNAMIC only.)

:PAGE The index of the page the object resides on. (GENGC and :SPACE :DYNAMIC only.)

For :STACK objects secondary value is the thread on whose stack the object is allocated.

Expected use-cases include introspection to gain insight into allocation and GC behaviour and restricting memoization to heap-allocated arguments.

Experimental: interface subject to change.

Lambda list

(sb-introspect::object)