// Garbage collector (GC).
//
-// The GC runs concurrently with mutator threads, is type accurate (aka precise), allows multiple GC
-// thread to run in parallel. It is a concurrent mark and sweep that uses a write barrier. It is
+// The GC runs concurrently with mutator threads, is type accurate (aka precise), allows multiple
+// GC thread to run in parallel. It is a concurrent mark and sweep that uses a write barrier. It is
// non-generational and non-compacting. Allocation is done using size segregated per P allocation
// areas to minimize fragmentation while eliminating locks in the common case.
//
//
// The algorithm's intellectual heritage includes Dijkstra's on-the-fly algorithm, see
// Edsger W. Dijkstra, Leslie Lamport, A. J. Martin, C. S. Scholten, and E. F. M. Steffens. 1978.
-// On-the-fly garbage collection: an exercise in cooperation. Commun. ACM 21, 11 (November 1978), 966-975.
+// On-the-fly garbage collection: an exercise in cooperation. Commun. ACM 21, 11 (November 1978),
+// 966-975.
// For journal quality proofs that these steps are complete, correct, and terminate see
// Hudson, R., and Moss, J.E.B. Copying Garbage Collection without stopping the world.
// Concurrency and Computation: Practice and Experience 15(3-5), 2003.
// At this point all goroutines have passed through a GC safepoint and
// know we are in the GCscan phase.
// 2. GC scans all goroutine stacks, mark and enqueues all encountered pointers
-// (marking avoids most duplicate enqueuing but races may produce duplication which is benign).
+// (marking avoids most duplicate enqueuing but races may produce benign duplication).
// Preempted goroutines are scanned before P schedules next goroutine.
// 3. Set phase = GCmark.
// 4. Wait for all P's to acknowledge phase change.
// 9. Wait for all P's to acknowledge phase change.
// 10. Malloc now allocates black objects, so number of unmarked reachable objects
// monotonically decreases.
-// 11. GC preempts P's one-by-one taking partial wbufs and marks all unmarked yet reachable objects.
+// 11. GC preempts P's one-by-one taking partial wbufs and marks all unmarked yet
+// reachable objects.
// 12. When GC completes a full cycle over P's and discovers no new grey
// objects, (which means all reachable objects are marked) set phase = GCsweep.
// 13. Wait for all P's to acknowledge phase change.
// that many pages into heap. Together these two measures ensure that we don't surpass
// target next_gc value by a large margin. There is an exception: if a goroutine sweeps
// and frees two nonadjacent one-page spans to the heap, it will allocate a new two-page span,
-// but there can still be other one-page unswept spans which could be combined into a two-page span.
+// but there can still be other one-page unswept spans which could be combined into a
+// two-page span.
// It's critical to ensure that no operations proceed on unswept spans (that would corrupt
// mark bits in GC bitmap). During GC all mcaches are flushed into the central cache,
// so they are empty. When a goroutine grabs a new span into mcache, it sweeps it.