STL MAP内存释放测试

测试过程：

insert采用malloc分配内存，释放时采用free释放内存，并erase操作子。使用top窗口查看程序使用的内存。

测试结果：

free后，操作系统为程序分配的内存并不会free掉，而被Hold了。当再次调用insert入map，会使用未free掉的内存。

如果后面insert同样采用malloc分配内存，操作系统会优先使用先去malloc且free掉的内存，若不够再malloc新内存。

测试代码如下：

?

#include <iostream>#include <map>#include <ext/hash_map>using namespace std;using namespace __gnu_cxx;#pragma pack(1)typedef struct{uint32_tuiUserId;//Systematic distribution id for every  UserPhone;uint8_tucFlag;//first send flag:0,no send;1,senduint8_tucAlter;//user can send msg:0,no;1,yescharszUserPhone[14];//user phone numberuint32_tuiLastestBscID;uint32_tuiLastestAreaID;time_tuiMonthBeginTime;//cur month send num begin timetime_tuiLastestSendTime;//last send welcome sms timetime_tuiFirstSendTime;//first send welcome sms timeuint16_tusDaySendNum;//send count every dayuint16_tusMonthSendNum;//send count every monthuint16_tusTotal;//send total countuint32_tuiAreaList[5];}CUserInFile;#pragma pack()#define LEN sizeof(CUserInFile)typedef map<int,CUserInFile*> UserMap;UserMap userMap;int main(){FILE *fp;char buff[LEN];int i=0;fp=fopen("userprofile_wifi","r");memset(buff,0x00,LEN);while(fread(buff,1,LEN,fp)==LEN){fseek(fp,SEEK_CUR,LEN);//fwrite(buff,LEN,10,fpw);CUserInFile* pUser=(CUserInFile*)malloc(LEN);userMap.insert(make_pair(i++,pUser));}fclose(fp);//fclose(fpw);printf("insert ok:%d\n",i);getchar();UserMap::iterator it;for(it=userMap.begin();it!=userMap.end();++it){if(it->second==NULL){printf("dasdsadas\n");continue;}CUserInFile* pUser=it->second;free(pUser);userMap.erase(it);}printf("free ok\n");getchar();fp=fopen("userprofile_wifi","r");memset(buff,0x00,LEN);while(fread(buff,1,LEN,fp)){fseek(fp,SEEK_CUR,LEN);CUserInFile* pUser=(CUserInFile*)malloc(LEN);userMap.insert(make_pair(i++,pUser));}fclose(fp);printf("insert again ok\n");getchar();return 0;}

?后面测试了HASH_MAP，结论类似。