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今天在改一个程序，改成部分逻辑用lua写，这个程序是多线程的。将程序中部分逻辑改成lua之后，各种非法访问内存错误，各种奇奇怪怪的问题，不分时间，不分地点的出现崩溃。从调用堆栈来看，基本都是使用lua造成的。在多线程中使用lua_newthread得到的lus_State仍然有时候程序会崩溃。基本上可以确定为多线程中操作lua 的问题了。 前几天我转载的一篇文章，文章写了关于lua多线程的作法。作法有二 1.每一个线程函数用lua_newthread产生一个新的lua_state 以后对lua操作都用这个lua_state 2.修改lua源码使之成为支持多线程的（修改lua 源代码中lua_lock lua_unlock宏） 对于第2条，那篇文中的例子是用 pthread_mutex_t 来进行线程同步的pthread_mutex_t，我对pthread_mutex_t 不熟，网上一查才知道一般是在linux下C语言进行线程同步用的，在windows下面一般多线程都用CRITICAL_SECTION，和内核对象来进行线程同步的。于是产生了这篇文章。 修改代码如下： 1.global_State加一个成员变量 m_cs
typedef struct global_State {
stringtable strt; /* hash table for strings */
lua_Alloc frealloc; /* function to reallocate memory */
void *ud; /* auxiliary data to `frealloc' */
lu_byte currentwhite;
lu_byte gcstate; /* state of garbage collector */
int sweepstrgc; /* position of sweep in `strt' */
GCObject *rootgc; /* list of all collectable objects */
GCObject **sweepgc; /* position of sweep in `rootgc' */
GCObject *gray; /* list of gray objects */
GCObject *grayagain; /* list of objects to be traversed atomically */
GCObject *weak; /* list of weak tables (to be cleared) */
GCObject *tmudata; /* last element of list of userdata to be GC */
Mbuffer buff; /* temporary buffer for string concatentation */
lu_mem GCthreshold;
lu_mem totalbytes; /* number of bytes currently allocated */
lu_mem estimate; /* an estimate of number of bytes actually in use */
lu_mem gcdept; /* how much GC is `behind schedule' */
int gcpause; /* size of pause between successive GCs */
int gcstepmul; /* GC `granularity' */
lua_CFunction panic; /* to be called in unprotected errors */
TValue l_registry;
struct lua_State *mainthread;
UpVal uvhead; /* head of double-linked list of all open upvalues */
struct Table *mt[NUM_TAGS]; /* metatables for basic types */
TString *tmname[TM_N]; /* array with tag-method names */
CRITICAL_SECTION m_cs; /*windows mutithread */
} global_State;
2.在lua_newstate加入初始化Critical_section的代码 InitializeCriticalSection(&g->m_cs);
LUA_API lua_State *lua_newstate (lua_Alloc f, void *ud) {
int i;
lua_State *L;
global_State *g;
void *l = (*f)(ud, NULL, 0, state_size(LG));
if (l == NULL) return NULL;
L = tostate(l);
g = &((LG *)L)->g;
L->next = NULL;
L->tt = LUA_TTHREAD;
g->currentwhite = bit2mask(WHITE0BIT, FIXEDBIT);
L->marked = luaC_white(g);
set2bits(L->marked, FIXEDBIT, SFIXEDBIT);
preinit_state(L, g);
g->frealloc = f;
g->ud = ud;
g->mainthread = L;
g->uvhead.u.l.prev = &g->uvhead;
g->uvhead.u.l.next = &g->uvhead;
g->GCthreshold = 0; /* mark it as unfinished state */
g->strt.size = 0;
g->strt.nuse = 0;
g->strt.hash = NULL;
setnilvalue(registry(L));
luaZ_initbuffer(L, &g->buff);
g->panic = NULL;
g->gcstate = GCSpause;
g->rootgc = obj2gco(L);
g->sweepstrgc = 0;
g->sweepgc = &g->rootgc;
g->gray = NULL;
g->grayagain = NULL;
g->weak = NULL;
g->tmudata = NULL;
g->totalbytes = sizeof(LG);
g->gcpause = LUAI_GCPAUSE;
g->gcstepmul = LUAI_GCMUL;
g->gcdept = 0;
InitializeCriticalSection(&g->m_cs);
for (i=0; i<NUM_TAGS; i++) g->mt[i] = NULL;
if (luaD_rawrunprotected(L, f_luaopen, NULL) != 0) {
/* memory allocation error: free partial state */
close_state(L);
L = NULL;
}
else
luai_userstateopen(L);
return L;
}
3.在close_state 加入删除CriticalSection的代码 DeleteCriticalSection(&g->m_cs);
static void close_state (lua_State *L) {
global_State *g = G(L);
luaF_close(L, L->stack); /* close all upvalues for this thread */
luaC_freeall(L); /* collect all objects */
lua_assert(g->rootgc == obj2gco(L));
lua_assert(g->strt.nuse == 0);
luaM_freearray(L, G(L)->strt.hash, G(L)->strt.size, TString *);
luaZ_freebuffer(L, &g->buff);
freestack(L, L);
lua_assert(g->totalbytes == sizeof(LG));
DeleteCriticalSection(&g->m_cs);
(*g->frealloc)(g->ud, fromstate(L), state_size(LG), 0);
}
4.修改lua_lock和lua_unlock宏如下
#ifndef lua_lock
#define lua_lock(L) EnterCriticalSection(&(G(L)->m_cs))
#define lua_unlock(L) LeaveCriticalSection(&(G
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