lgc.h与lgc.c

三种颜色

（1）white：未标记

（2）grey：该对象标记，其引用未标记

（3）black：该对象及其所有引用均被标记

GC状态

GCSpropagate

调用propagatemark()，若g->grey为NULL，置状态为GCSatomic

GCSatomic

propagateall()

atomic()

entersweep()

GCSswpallgc

sweepstep()

GCSswpfinobj

sweepstep()

GCSswptobefnz

sweepstep()

GCSswpend

makewhite(g->mainthread)

GCScallfin

调用剩余的的finalizers，完成后转GCSpause

GCSpause

调用restartcollection()，状态转为GCSpropagate

内部以luaC_作为前缀

luaC_fix()

luaC_freeallobjects()

luaC_step()

luaC_runtilstate()

luaC_fullgc()

luaC_newobj()

luaC_barrier_()

luaC_barrierback_()

luaC_upvalbarrier_()

luaC_checkfinalizer()

luaC_upvdeccound()

Generic functions

Mark functions

reallymarkobject()

Userdata, strings, and closed upvalues设为black，其它对象暂设为灰并加入list，留待稍后继续访问。

markmt()

markbeingfnz()

remarkupvals()

restartcollection()

markobject(g->mainthread)

markvalue(g->l_registry)

markmt()

遍历g->mt中基本类型的metatable并标记

markbeingfnz()

遍历g->tobefnz链表中所有元素并标记（上一循环剩下的object）

Traverse functions

traverseweakvalue()

traverseephemeron()

traversestrongtable()

traversetable()

traverseproto()

traverseCclosure()

traverseLclosure()

traverseThread()

propagatemark()

propagateall()

遍历g->grey，并执行propagatemark()

convergeephemerons()

Sweep functions

Finalization

separatetobefnz()

move all unreadable objects that need finalization from list 'finobj' to list 'tobefnz'

GC control