C++多線(xiàn)程（一）

WIN 多線(xiàn)程API

一 簡(jiǎn)單實(shí)例
比較簡(jiǎn)單的代碼，創(chuàng)建10個(gè)線(xiàn)程，其中使第4個(gè)線(xiàn)程在一創(chuàng)建就掛起，等到其他的線(xiàn)程執(zhí)行的差不多的時(shí)候再使第4個(gè)線(xiàn)程恢復(fù)執(zhí)行。
#include?<stdio.h>?
#include?<stdlib.h>?
#include?<windows.h>?

#define?THREAD_NUM?10

DWORD?WINAPI?PrintThreads?(LPVOID);

int?main?()?
{?
????HANDLE?hThread[THREAD_NUM];?
????DWORD?dwThreadID[THREAD_NUM];?

????for?(int?i=0;?i<THREAD_NUM;?++i)?
????{?
????????int?isStartImmediate?=?0;
????????if(3?==?i)
????????????isStartImmediate?=?CREATE_SUSPENDED;
????????hThread[i]=CreateThread(NULL,????????????????//?security?attributes?that?should?be?applied?to?the?new?thread,?
??????????????????????????????????????????????????????????????????????????????? ?//?this?is?for?NT.?Use?NULL?to?get?the?default?security?attributes.?Use?NULL?for?win95?
????????????????????????????????0,??????????????????????????????????????????? //?default?size?of?1MB?can?be?passed?by?passing?zero.?
????????????????????????????????PrintThreads,???????????????????? //?function?name:address?of?the?function?where?the?new?thread?starts.
????????????????????????????????(LPVOID)i,???????????????????????? //?parameter(void?pointer):?pointer?to?the?32?bit?parameter?that?will?be?passed?into?the?thread
????????????????????????????????isStartImmediate,???????????? //?flags?to?control?the?creation?of?the?thread.?Passing?zero?starts?the?thread?immediately.?
?????????????????????????????????????????????????????????????????????????? //?Passing?CREATE_SUSPENDED?suspends?the?thread?until?the?ResumeThread(?)?function?is?called.
????????????????????????????????&dwThreadID[i]??????????? //?pointer?to?a?32-bit?variable?that?receives?the?thread?identifier.
????????????????????????????????);?
????????if?(hThread[i])
????????{?
????????????printf?("Thread?launched?successfully/n");????????????????
????????}?????????
????}?
????printf("Start?sleep?100,?and?let?other?thread?excute/n");
????Sleep?(100);????

????printf("Start?sleep?100,?and?thread?3?excute/n");
????ResumeThread(hThread[3]);
????
????Sleep(100);

????for(int?i?=?0;?i<THREAD_NUM;?++i)
????{
????????if?(hThread[i])
????????{????????????
????????????CloseHandle(hThread[i]);????//?You?need?to?use?this?to?release?kernel?objects?when?you?are?done?using?them.?
????????????????????????????????????????//?If?a?process?exits?without?closing?the?thread?handle,?
????????????????????????????????????????//?the?operating?system?drops?the?reference?counts?for?those?objects.?
????????????????????????????????????????//?But?if?a?process?frequently?creates?threads?without?closing?the?handles,?
????????????????????????????????????????//?there?could?be?hundreds?of?thread?kernel?objects?lying?around?and?these?resource?leaks?can?have?a?big?hit?on?performance.
????????}?
????}
????return?(0);?
}?

//function?PrintThreads?
DWORD?WINAPI?PrintThreads?(LPVOID?num)
{
????for?(int?i=0;?i<10;?i++)?
????????printf?("Thread?Number?is?%d%d%d/n",?num,num,num);?
????return?0;
}

二 其他基本API的說(shuō)明
CreateThread() 調(diào)用成功返回句柄和一個(gè)id。
CloseHandle()? 關(guān)閉一個(gè)打開(kāi)的對(duì)象句柄，該對(duì)象句柄可以是線(xiàn)程句柄，也可以是進(jìn)程、信號(hào)量等其他內(nèi)核對(duì)象的句柄.

SuspendThread(HANDLE) 允許開(kāi)發(fā)人員將HANDLE指定的線(xiàn)程掛起，如果要掛起的線(xiàn)程占有共享資源，則可能導(dǎo)致死鎖。
ResumeThread(HANDLE)? 恢復(fù)指定的線(xiàn)程。

TerminateThread() 立即終止線(xiàn)程的工作，不做任何清理工作。
ExitThread() 線(xiàn)程函數(shù)返回時(shí)回調(diào)用次函數(shù)，所以一般我們不去顯示的調(diào)用。

ExitThread是推薦使用的結(jié)束一個(gè)線(xiàn)程的方法，當(dāng)調(diào)用該函數(shù)時(shí)，當(dāng)前線(xiàn)程的棧被釋放，然后線(xiàn)程終止，相對(duì)于TerminateThread函數(shù)來(lái)說(shuō)，這樣做能夠更好地完成附加在該線(xiàn)程上的DLL的清除工作. 但是ExitThread()會(huì)導(dǎo)致線(xiàn)程在清處構(gòu)造器/自動(dòng)變量之前就終止，所以我們最好不要顯示的調(diào)用ExitThread()。

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