Sweep_internals.md

Field	Purpose
lock	Mutex used for protecting span and memory operations.
free	mTreap of non-scavenged spans, i.e., available memory that hasn’t been returned to the OS.
scav	mTreap of free and scavenged spans, i.e., memory ready to be reused or returned to the OS.
sweepgen	Tracks the current sweep generation for the garbage collector.
sweepdone	Indicates whether all spans in a generation have been swept.
sweepers	Number of active sweepone calls running concurrently.