#include <pthread.h> #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <queue> #include <vector> using std::vector; using std::queue; #define NUM_THREADS 3 static vector<queue<int> > vqueue; void *watch_count(void *t) { int i; long my_id = (long)t; for(;;) { while(!vqueue[my_id].empty()) { printf("watch_count(): thread %ld Condition signal received. Value = %d\n", my_id, vqueue[my_id].front()); vqueue[my_id].pop(); } } pthread_exit(NULL); } int main(int argc, char *argv[]) { long t1 = 0, t2 = 1, t3 = 2; pthread_t threads[3]; pthread_attr_t attr; /* For portability, explicitly create threads in a detached state */ pthread_attr_init(&attr); pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED); pthread_create(&threads[0], &attr, watch_count, (void *)t1); pthread_create(&threads[1], &attr, watch_count, (void *)t2); pthread_create(&threads[2], &attr, watch_count, (void *)t3); for(int i = 0; i < 21; ++i) { vqueue[i % 3].push(i); } while(1); /* Clean up and exit */ pthread_attr_destroy(&attr); pthread_exit (NULL); }
上面的程序中,本人想生成三个子线程,子线程一直循环处理相应的队列,主线程则负责添加任务到相应队列。这个程序在是有问题的,会产生coredump。但本人不知道问题在哪,还望各位高手指点,说说问题,说说多线程怎么处理。
原因猜测:莫非是原因是队列不是线性安全的?感觉应该还可以,原因是主线程只在队列末尾操作, 子线程在对头操作。
要是有,多线程相关书籍,服务器的, 关于c/c++的,也可以推荐。多谢大家啦!
解决方案
20
没有任何互斥保护导致的
10
仅供参考:
//循环向a函数每次发送200个字节长度(这个是固定的)的buffer, //a函数中需要将循环传进来的buffer,组成240字节(也是固定的)的新buffer进行处理, //在处理的时候每次从新buffer中取两个字节打印 #ifdef _MSC_VER #pragma warning(disable:4996) #endif #include <stdio.h> #include <stdlib.h> #include <string.h> #ifdef _MSC_VER #include <windows.h> #include <process.h> #include <io.h> #define MYVOID void #define vsnprintf _vsnprintf #else #include <unistd.h> #include <sys/time.h> #include <pthread.h> #define CRITICAL_SECTION pthread_mutex_t #define MYVOID void * #endif //Log{ #define MAXLOGSIZE 20000000 #define MAXLINSIZE 16000 #include <time.h> #include <sys/timeb.h> #include <stdarg.h> char logfilename1[]="MyLog1.log"; char logfilename2[]="MyLog2.log"; static char logstr[MAXLINSIZE+1]; char datestr[16]; char timestr[16]; char mss[4]; CRITICAL_SECTION cs_log; FILE *flog; #ifdef _MSC_VER void Lock(CRITICAL_SECTION *l) { EnterCriticalSection(l); } void Unlock(CRITICAL_SECTION *l) { LeaveCriticalSection(l); } void sleep_ms(int ms) { Sleep(ms); } #else void Lock(CRITICAL_SECTION *l) { pthread_mutex_lock(l); } void Unlock(CRITICAL_SECTION *l) { pthread_mutex_unlock(l); } void sleep_ms(int ms) { usleep(ms*1000); } #endif void LogV(const char *pszFmt,va_list argp) { struct tm *now; struct timeb tb; if (NULL==pszFmt||0==pszFmt[0]) return; vsnprintf(logstr,MAXLINSIZE,pszFmt,argp); ftime(&tb); now=localtime(&tb.time); sprintf(datestr,"%04d-%02d-%02d",now->tm_year+1900,now->tm_mon+1,now->tm_mday); sprintf(timestr,"%02d:%02d:%02d",now->tm_hour ,now->tm_min ,now->tm_sec ); sprintf(mss,"%03d",tb.millitm); printf("%s %s.%s %s",datestr,timestr,mss,logstr); flog=fopen(logfilename1,"a"); if (NULL!=flog) { fprintf(flog,"%s %s.%s %s",datestr,timestr,mss,logstr); if (ftell(flog)>MAXLOGSIZE) { fclose(flog); if (rename(logfilename1,logfilename2)) { remove(logfilename2); rename(logfilename1,logfilename2); } } else { fclose(flog); } } } void Log(const char *pszFmt,...) { va_list argp; Lock(&cs_log); va_start(argp,pszFmt); LogV(pszFmt,argp); va_end(argp); Unlock(&cs_log); } //Log} #define ASIZE 200 #define BSIZE 240 #define CSIZE 2 char Abuf[ASIZE]; char Cbuf[CSIZE]; CRITICAL_SECTION cs_HEX ; CRITICAL_SECTION cs_BBB ; struct FIFO_BUFFER { int head; int tail; int size; char data[BSIZE]; } BBB; int No_Loop=0; void HexDump(int cn,char *buf,int len) { int i,j,k; char binstr[80]; Lock(&cs_HEX); for (i=0;i<len;i++) { if (0==(i%16)) { sprintf(binstr,"%03d %04x -",cn,i); sprintf(binstr,"%s %02x",binstr,(unsigned char)buf[i]); } else if (15==(i%16)) { sprintf(binstr,"%s %02x",binstr,(unsigned char)buf[i]); sprintf(binstr,"%s ",binstr); for (j=i-15;j<=i;j++) { sprintf(binstr,"%s%c",binstr,("!"<buf[j]&&buf[j]<="~")?buf[j]:"."); } Log("%s\n",binstr); } else { sprintf(binstr,"%s %02x",binstr,(unsigned char)buf[i]); } } if (0!=(i%16)) { k=16-(i%16); for (j=0;j<k;j++) { sprintf(binstr,"%s ",binstr); } sprintf(binstr,"%s ",binstr); k=16-k; for (j=i-k;j<i;j++) { sprintf(binstr,"%s%c",binstr,("!"<buf[j]&&buf[j]<="~")?buf[j]:"."); } Log("%s\n",binstr); } Unlock(&cs_HEX); } int GetFromRBuf(int cn,CRITICAL_SECTION *cs,struct FIFO_BUFFER *fbuf,char *buf,int len) { int lent,len1,len2; lent=0; Lock(cs); if (fbuf->size>=len) { lent=len; if (fbuf->head+lent>BSIZE) { len1=BSIZE-fbuf->head; memcpy(buf ,fbuf->data+fbuf->head,len1); len2=lent-len1; memcpy(buf+len1,fbuf->data ,len2); fbuf->head=len2; } else { memcpy(buf ,fbuf->data+fbuf->head,lent); fbuf->head+=lent; } fbuf->size-=lent; } Unlock(cs); return lent; } MYVOID thdB(void *pcn) { char *recv_buf; int recv_nbytes; int cn; int wc; int pb; cn=(int)pcn; Log("%03d thdB thread begin...\n",cn); while (1) { sleep_ms(10); recv_buf=(char *)Cbuf; recv_nbytes=CSIZE; wc=0; while (1) { pb=GetFromRBuf(cn,&cs_BBB,&BBB,recv_buf,recv_nbytes); if (pb) { Log("%03d recv %d bytes\n",cn,pb); HexDump(cn,recv_buf,pb); sleep_ms(1); } else { sleep_ms(1000); } if (No_Loop) break;// wc++; if (wc>3600) Log("%03d %d==wc>3600!\n",cn,wc); } if (No_Loop) break;// } #ifndef _MSC_VER pthread_exit(NULL); #endif } int PutToRBuf(int cn,CRITICAL_SECTION *cs,struct FIFO_BUFFER *fbuf,char *buf,int len) { int lent,len1,len2; Lock(cs); lent=len; if (fbuf->size+lent>BSIZE) { lent=BSIZE-fbuf->size; } if (fbuf->tail+lent>BSIZE) { len1=BSIZE-fbuf->tail; memcpy(fbuf->data+fbuf->tail,buf ,len1); len2=lent-len1; memcpy(fbuf->data ,buf+len1,len2); fbuf->tail=len2; } else { memcpy(fbuf->data+fbuf->tail,buf ,lent); fbuf->tail+=lent; } fbuf->size+=lent; Unlock(cs); return lent; } MYVOID thdA(void *pcn) { char *send_buf; int send_nbytes; int cn; int wc; int a; int pa; cn=(int)pcn; Log("%03d thdA thread begin...\n",cn); a=0; while (1) { sleep_ms(100); memset(Abuf,a,ASIZE); a=(a+1)%256; if (16==a) {No_Loop=1;break;}//去掉这句可以让程序一直循环直到按Ctrl+C或Ctrl+Break或当前目录下存在文件No_Loop send_buf=(char *)Abuf; send_nbytes=ASIZE; Log("%03d sending %d bytes\n",cn,send_nbytes); HexDump(cn,send_buf,send_nbytes); wc=0; while (1) { pa=PutToRBuf(cn,&cs_BBB,&BBB,send_buf,send_nbytes); Log("%03d sent %d bytes\n",cn,pa); HexDump(cn,send_buf,pa); send_buf+=pa; send_nbytes-=pa; if (send_nbytes<=0) break;// sleep_ms(1000); if (No_Loop) break;// wc++; if (wc>3600) Log("%03d %d==wc>3600!\n",cn,wc); } if (No_Loop) break;// } #ifndef _MSC_VER pthread_exit(NULL); #endif } int main() { #ifdef _MSC_VER InitializeCriticalSection(&cs_log); InitializeCriticalSection(&cs_HEX ); InitializeCriticalSection(&cs_BBB ); #else pthread_t threads[2]; int threadsN; int rc; pthread_mutex_init(&cs_log,NULL); pthread_mutex_init(&cs_HEX,NULL); pthread_mutex_init(&cs_BBB,NULL); #endif Log("Start===========================================================\n"); BBB.head=0; BBB.tail=0; BBB.size=0; #ifdef _MSC_VER _beginthread((void(__cdecl *)(void *))thdA,0,(void *)1); _beginthread((void(__cdecl *)(void *))thdB,0,(void *)2); #else threadsN=0; rc=pthread_create(&(threads[threadsN++]),NULL,thdA,(void *)1);if (rc) Log("%d=pthread_create %d error!\n",rc,threadsN-1); rc=pthread_create(&(threads[threadsN++]),NULL,thdB,(void *)2);if (rc) Log("%d=pthread_create %d error!\n",rc,threadsN-1); #endif if (!access("No_Loop",0)) { remove("No_Loop"); if (!access("No_Loop",0)) { No_Loop=1; } } while (1) { sleep_ms(1000); if (No_Loop) break;// if (!access("No_Loop",0)) { No_Loop=1; } } sleep_ms(3000); Log("End=============================================================\n"); #ifdef _MSC_VER DeleteCriticalSection(&cs_BBB ); DeleteCriticalSection(&cs_HEX ); DeleteCriticalSection(&cs_log); #else pthread_mutex_destroy(&cs_BBB); pthread_mutex_destroy(&cs_HEX); pthread_mutex_destroy(&cs_log); #endif return 0; }