windows lua 多线程 线程同步

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

Code Snippet
  1. typedef struct global_State {
  2.   stringtable strt;  /* hash table for strings */
  3.   lua_Alloc frealloc;  /* function to reallocate memory */
  4.   void *ud;         /* auxiliary data to `frealloc' */
  5.   lu_byte currentwhite;
  6.   lu_byte gcstate;  /* state of garbage collector */
  7.   int sweepstrgc;  /* position of sweep in `strt' */
  8.   GCObject *rootgc;  /* list of all collectable objects */
  9.   GCObject **sweepgc;  /* position of sweep in `rootgc' */
  10.   GCObject *gray;  /* list of gray objects */
  11.   GCObject *grayagain;  /* list of objects to be traversed atomically */
  12.   GCObject *weak;  /* list of weak tables (to be cleared) */
  13.   GCObject *tmudata;  /* last element of list of userdata to be GC */
  14.   Mbuffer buff;  /* temporary buffer for string concatentation */
  15.   lu_mem GCthreshold;
  16.   lu_mem totalbytes;  /* number of bytes currently allocated */
  17.   lu_mem estimate;  /* an estimate of number of bytes actually in use */
  18.   lu_mem gcdept;  /* how much GC is `behind schedule' */
  19.   int gcpause;  /* size of pause between successive GCs */
  20.   int gcstepmul;  /* GC `granularity' */
  21.   lua_CFunction panic;  /* to be called in unprotected errors */
  22.   TValue l_registry;
  23.   struct lua_State *mainthread;
  24.   UpVal uvhead;  /* head of double-linked list of all open upvalues */
  25.   struct Table *mt[NUM_TAGS];  /* metatables for basic types */
  26.   TString *tmname[TM_N];  /* array with tag-method names */
  27.   CRITICAL_SECTION m_cs; /*windows mutithread */
  28. } global_State;

 

2.在lua_newstate加入初始化Critical_section的代码 InitializeCriticalSection(&g->m_cs);

Code Snippet
  1. LUA_API lua_State *lua_newstate (lua_Alloc f, void *ud) {
  2.   int i;
  3.   lua_State *L;
  4.   global_State *g;
  5.   void *l = (*f)(ud, NULL, 0, state_size(LG));
  6.   if (l == NULL) return NULL;
  7.   L = tostate(l);
  8.   g = &((LG *)L)->g;
  9.   L->next = NULL;
  10.   L->tt = LUA_TTHREAD;
  11.   g->currentwhite = bit2mask(WHITE0BIT, FIXEDBIT);
  12.   L->marked = luaC_white(g);
  13.   set2bits(L->marked, FIXEDBIT, SFIXEDBIT);
  14.   preinit_state(L, g);
  15.   g->frealloc = f;
  16.   g->ud = ud;
  17.   g->mainthread = L;
  18.   g->uvhead.u.l.prev = &g->uvhead;
  19.   g->uvhead.u.l.next = &g->uvhead;
  20.   g->GCthreshold = 0;  /* mark it as unfinished state */
  21.   g->strt.size = 0;
  22.   g->strt.nuse = 0;
  23.   g->strt.hash = NULL;
  24.   setnilvalue(registry(L));
  25.   luaZ_initbuffer(L, &g->buff);
  26.   g->panic = NULL;
  27.   g->gcstate = GCSpause;
  28.   g->rootgc = obj2gco(L);
  29.   g->sweepstrgc = 0;
  30.   g->sweepgc = &g->rootgc;
  31.   g->gray = NULL;
  32.   g->grayagain = NULL;
  33.   g->weak = NULL;
  34.   g->tmudata = NULL;
  35.   g->totalbytes = sizeof(LG);
  36.   g->gcpause = LUAI_GCPAUSE;
  37.   g->gcstepmul = LUAI_GCMUL;
  38.   g->gcdept = 0;
  39.   InitializeCriticalSection(&g->m_cs);
  40.   for (i=0; i<NUM_TAGS; i++) g->mt[i] = NULL;
  41.   if (luaD_rawrunprotected(L, f_luaopen, NULL) != 0) {
  42.     /* memory allocation error: free partial state */
  43.     close_state(L);
  44.     L = NULL;
  45.   }
  46.   else
  47.     luai_userstateopen(L);
  48.   return L;
  49. }

3.在close_state 加入删除CriticalSection的代码 DeleteCriticalSection(&g->m_cs);

Code Snippet
  1. static void close_state (lua_State *L) {
  2.   global_State *g = G(L);
  3.   luaF_close(L, L->stack);  /* close all upvalues for this thread */
  4.   luaC_freeall(L);  /* collect all objects */
  5.   lua_assert(g->rootgc == obj2gco(L));
  6.   lua_assert(g->strt.nuse == 0);
  7.   luaM_freearray(L, G(L)->strt.hash, G(L)->strt.size, TString *);
  8.   luaZ_freebuffer(L, &g->buff);
  9.   freestack(L, L);
  10.   lua_assert(g->totalbytes == sizeof(LG));
  11.   DeleteCriticalSection(&g->m_cs);
  12.   (*g->frealloc)(g->ud, fromstate(L), state_size(LG), 0);
  13. }

4.修改lua_lock和lua_unlock宏如下

Code Snippet
  1. #ifndef lua_lock
  2. #define lua_lock(L) EnterCriticalSection(&(G(L)->m_cs))
  3. #define lua_unlock(L) LeaveCriticalSection(&(G(L)->m_cs))
  4. #endif

5.为了使用CRITICAL_SECTION我们比较通用的方法是包含头文件 windows.h，但包含后发现，lua库中的LoadString函数正好与windows  api LoadString同名。所以把lua库内部所使用的LoadString通通改为LUA_LoadString即可

修改完之后，在控制台写了四个线程一个一个主lua_state，四个线程使用lua_newthread得到的lua_state，没有再出现错误了。

posted @ 2014-04-21 19:00  瓜蛋  阅读(6942)  评论(2)  编辑  收藏  举报