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[求助]关于WaitForSingleObject
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发表于: 2009-10-17 18:17
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写了一个不规范的程序:
在“rr=”不被注释掉的情况下正常
在“rr=”被注释掉以后，即rr=NULL时，程序出现不可信状况……
描述：输入一个delta后，程序执行后有时会执行两次
但是不管哪一次，反汇编都是一样的：
这是怎么回事呢？
WaitForSingleObject使用NULL后不是不等待了吗？
哪位大侠能帮忙分析下程序不可信的原因，谢谢！
// threadSD0.cpp : Defines the entry point for the console application.
//
#include "stdafx.h"
#include <windows.h>
#include <stdio.h>
int a;
DWORD WINAPI incp(LPVOID lpParameter) {
a++;
ExitThread(0);
return 0;
}
DWORD WINAPI decp(LPVOID lpParameter) {
a--;
ExitThread(0);
return 0;
}
DWORD WINAPI prnp(LPVOID lpParameter) {
printf("%2d",a);
ExitThread(0);
return 0;
}
int main(int argc, char* argv[])
{
int delta=0;
VOID* rr=NULL;
UINT count=0;
long t;
long tmp;
printf("input delta: ");
scanf("%d",&delta);
t=GetTickCount();
tmp=GetTickCount();
while(tmp-t<delta) {
CreateThread(NULL,100,incp,NULL,0,0);
CreateThread(NULL,100,decp,NULL,0,0);
//rr=
CreateThread(NULL,100,prnp,NULL,0,0);
count++;
tmp=GetTickCount();
}
WaitForSingleObject(rr,INFINITE);
printf("\n-- Over Now...\n-- Times %u for Time %ld\n",count,tmp-t);
return 0;
}
在“rr=”不被注释掉的情况下正常
在“rr=”被注释掉以后，即rr=NULL时，程序出现不可信状况……
描述：输入一个delta后，程序执行后有时会执行两次
printf("\n-- Over Now...\n-- Times %u for Time %ld\n",count,tmp-t);但是不管哪一次，反汇编都是一样的：
24:
25: int main(int argc, char* argv[])
26: {
00401160 55 push ebp
00401161 8B EC mov ebp,esp
00401163 83 EC 54 sub esp,54h
00401166 53 push ebx
00401167 56 push esi
00401168 57 push edi
00401169 8D 7D AC lea edi,[ebp-54h]
0040116C B9 15 00 00 00 mov ecx,15h
00401171 B8 CC CC CC CC mov eax,0CCCCCCCCh
00401176 F3 AB rep stos dword ptr [edi]
27: int delta=0;
00401178 C7 45 FC 00 00 00 00 mov dword ptr [ebp-4],0
28: VOID* rr=0;
0040117F C7 45 F8 00 00 00 00 mov dword ptr [ebp-8],0
29: UINT count=0;
00401186 C7 45 F4 00 00 00 00 mov dword ptr [ebp-0Ch],0
30: long t;
31: long tmp;
32: printf("input delta: ");
0040118D 68 3C 20 42 00 push offset string "input delta: " (0042203c)
00401192 E8 89 01 00 00 call printf (00401320)
00401197 83 C4 04 add esp,4
33: scanf("%d",&delta);
0040119A 8D 45 FC lea eax,[ebp-4]
0040119D 50 push eax
0040119E 68 38 20 42 00 push offset string "%d" (00422038)
004011A3 E8 F8 01 00 00 call scanf (004013a0)
004011A8 83 C4 08 add esp,8
34: t=GetTickCount();
004011AB 8B F4 mov esi,esp
004011AD FF 15 5C 71 42 00 call dword ptr [__imp__GetTickCount@0 (0042715c)]
004011B3 3B F4 cmp esi,esp
004011B5 E8 26 01 00 00 call __chkesp (004012e0)
004011BA 89 45 F0 mov dword ptr [ebp-10h],eax
35: tmp=GetTickCount();
004011BD 8B F4 mov esi,esp
004011BF FF 15 5C 71 42 00 call dword ptr [__imp__GetTickCount@0 (0042715c)]
004011C5 3B F4 cmp esi,esp
004011C7 E8 14 01 00 00 call __chkesp (004012e0)
004011CC 89 45 EC mov dword ptr [ebp-14h],eax
36: while(tmp-t<delta) {
004011CF 8B 4D EC mov ecx,dword ptr [ebp-14h]
004011D2 2B 4D F0 sub ecx,dword ptr [ebp-10h]
004011D5 3B 4D FC cmp ecx,dword ptr [ebp-4]
004011D8 7D 7A jge main+0F4h (00401254)
37: CreateThread(NULL,100,incp,NULL,0,0);
004011DA 8B F4 mov esi,esp
004011DC 6A 00 push 0
004011DE 6A 00 push 0
004011E0 6A 00 push 0
004011E2 68 14 10 40 00 push offset @ILT+15(incp) (00401014)
004011E7 6A 64 push 64h
004011E9 6A 00 push 0
004011EB FF 15 58 71 42 00 call dword ptr [__imp__CreateThread@24 (00427158)]
004011F1 3B F4 cmp esi,esp
004011F3 E8 E8 00 00 00 call __chkesp (004012e0)
38: CreateThread(NULL,100,decp,NULL,0,0);
004011F8 8B F4 mov esi,esp
004011FA 6A 00 push 0
004011FC 6A 00 push 0
004011FE 6A 00 push 0
00401200 68 05 10 40 00 push offset @ILT+0(decp) (00401005)
00401205 6A 64 push 64h
00401207 6A 00 push 0
00401209 FF 15 58 71 42 00 call dword ptr [__imp__CreateThread@24 (00427158)]
0040120F 3B F4 cmp esi,esp
00401211 E8 CA 00 00 00 call __chkesp (004012e0)
39: CreateThread(NULL,100,prnp,NULL,0,0);
00401216 8B F4 mov esi,esp
00401218 6A 00 push 0
0040121A 6A 00 push 0
0040121C 6A 00 push 0
0040121E 68 0A 10 40 00 push offset @ILT+5(prnp) (0040100a)
00401223 6A 64 push 64h
00401225 6A 00 push 0
00401227 FF 15 58 71 42 00 call dword ptr [__imp__CreateThread@24 (00427158)]
0040122D 3B F4 cmp esi,esp
0040122F E8 AC 00 00 00 call __chkesp (004012e0)
40: count++;
00401234 8B 55 F4 mov edx,dword ptr [ebp-0Ch]
00401237 83 C2 01 add edx,1
0040123A 89 55 F4 mov dword ptr [ebp-0Ch],edx
41: tmp=GetTickCount();
0040123D 8B F4 mov esi,esp
0040123F FF 15 5C 71 42 00 call dword ptr [__imp__GetTickCount@0 (0042715c)]
00401245 3B F4 cmp esi,esp
00401247 E8 94 00 00 00 call __chkesp (004012e0)
0040124C 89 45 EC mov dword ptr [ebp-14h],eax
42: }
0040124F E9 7B FF FF FF jmp main+6Fh (004011cf)
43: WaitForSingleObject(rr,INFINITE);
00401254 8B F4 mov esi,esp
00401256 6A FF push 0FFh
00401258 8B 45 F8 mov eax,dword ptr [ebp-8]
0040125B 50 push eax
0040125C FF 15 54 71 42 00 call dword ptr [__imp__WaitForSingleObject@8 (00427154)]
00401262 3B F4 cmp esi,esp
00401264 E8 77 00 00 00 call __chkesp (004012e0)
44: printf("\n-- Over Now...\n-- Times %u for Time %ld\n);",count,tmp-t);
00401269 8B 4D EC mov ecx,dword ptr [ebp-14h]
0040126C 2B 4D F0 sub ecx,dword ptr [ebp-10h]
0040126F 51 push ecx
00401270 8B 55 F4 mov edx,dword ptr [ebp-0Ch]
00401273 52 push edx
00401274 68 F8 2F 42 00 push offset string "\n-- Over Now...\n-- Times %u for "... (00422ff8)
00401279 E8 A2 00 00 00 call printf (00401320)
0040127E 83 C4 0C add esp,0Ch
45: return 0;
00401281 33 C0 xor eax,eax
46: }
00401283 5F pop edi
00401284 5E pop esi
00401285 5B pop ebx
00401286 83 C4 54 add esp,54h
00401289 3B EC cmp ebp,esp
0040128B E8 50 00 00 00 call __chkesp (004012e0)
00401290 8B E5 mov esp,ebp
00401292 5D pop ebp
00401293 C3 ret
这是怎么回事呢？
WaitForSingleObject使用NULL后不是不等待了吗？
哪位大侠能帮忙分析下程序不可信的原因，谢谢！
[注意]传递专业知识、拓宽行业人脉——看雪讲师团队等你加入！
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厄,我的问题是:
当WaiForSingleObject的是NULL(即WaiForSingleObject(NULL,INFINITE);), printf("\n-- Over Now...\n-- Times %u for Time %ld\n",count,tmp-t); 有时会运行两次是什么原因..... 厄,不好意思,楼上摘的是MSDN.......貌似和问题有点差距... 附录: 当输入delta=2000时,  最后一个printf有时运行了两次, 不过实际滴答数差t-tmp不同,一个是2012,一个是2013 以上程序在: VC6+Win2K下调试 和 VC6+WinVista下调试过 |
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唉,没有人知道吗....
厄,还是继续研究ThreadPool吧.....
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