1. 首页
  2. 问答
  3. 生产者 - 消费者日志文件输出重复

生产者 - 消费者日志文件输出重复

2013-10-26 32 views
0

我在生产者 - 消费者问题的执行过程中遇到了一些问题。它似乎大部分运行良好，但是当我实施一个记录重要事件的日志文件时，我意识到事件有一些重复。这是否是由于文件操作不是相互排斥或者是否有其他可能导致此问题的东西？我在Ubuntu 12.04虚拟机上运行代码。生产者 - 消费者日志文件输出重复

#include <iostream> 
#include <pthread.h> 
#include <cstdlib> 
#include <signal.h> 
#include <unistd.h> 
#include <time.h> 
#include <stdio.h> 
#include <sstream> 
using namespace std; 
string trimspace(string); 
char* createString(string); 
void* producer(); 
void* consumer(); 
void createArray(int); 
int produceItem(); 
void createProducers(int); 
void createConsumers(int); 
void signalHandler(int); 
int full=0; 
int front=0; 
int rear=0; 
int empty; 
int BUFFER_SIZE; 
int producerCount; 
int consumerCount; 
int* buffer; 
bool running; 
FILE* logFile; 
timespec pts; 
timespec cts; 
pthread_t* producers; 
pthread_t* consumers; 
pthread_mutex_t counter_mutex= PTHREAD_MUTEX_INITIALIZER; 
pthread_mutex_t condp_mutex= PTHREAD_MUTEX_INITIALIZER; 
pthread_mutex_t condc_mutex= PTHREAD_MUTEX_INITIALIZER; 
pthread_cond_t condVarProd; 
pthread_cond_t condVarCons; 
int main() 
{ 
    running=true; 
    pthread_cond_init(&condVarCons,NULL); 
    pthread_cond_init(&condVarProd,NULL); 
    srand (time(NULL)); 
    signal(SIGINT, signalHandler); 
    full=0; 
    BUFFER_SIZE=0; 
    string data; 
    cout<<"How many producers would you like to create? "; 
    getline(cin,data); 
    data=trimspace(data); 
    char* data2=createString(data); 
    producerCount=atoi(data2); 
    free (data2); 
    while (producerCount<=0){ 
     cout<<"Please enter a valid number of producers to create! "; 
     getline(cin,data); 
     data=trimspace(data); 
     data2=createString(data); 
     producerCount=atoi(data2); 
     free (data2); 
    } 
    cout<<"How many consumers would you like to create? "; 
    getline(cin,data); 
    data=trimspace(data); 
    data2=createString(data); 
    consumerCount=atoi(data2); 
    free(data2); 
    while (consumerCount<=0){ 
     cout<<"Please enter a valid number of consumers to create! "; 
     getline(cin,data); 
     data=trimspace(data); 
     data2=createString(data); 
     consumerCount=atoi(data2); 
     free (data2); 
    }cout<<"How large of a rotating buffer would you like to create? "; 
    getline(cin,data); 
    data=trimspace(data); 
    data2=createString(data); 
    BUFFER_SIZE=atoi(data2); 
    free(data2); 
    while (BUFFER_SIZE<=0){ 
     cout<<"Please enter a valid buffer size to create! "; 
     getline(cin,data); 
     data=trimspace(data); 
     data2=createString(data); 
     BUFFER_SIZE=atoi(data2); 
     free (data2); 
    } 
    cout<<"What would you like to name your logfile? "; 
     getline (cin,data); 
     data=trimspace(data); 
     data2=createString(data); 
     logFile=fopen(data2,"a"); 
     free(data2); 
    empty=BUFFER_SIZE; 
    createArray(BUFFER_SIZE); 
    int i; 
    createProducers(producerCount); 
    createConsumers(consumerCount); 
    for (i=0; i<producerCount;i++){ 
     pthread_create(&producers[i], NULL, (void * (*)(void *))&producer, NULL); 
    } 
    for (i=0; i<consumerCount;i++){ 
     pthread_create(&consumers[i], NULL, (void * (*)(void *))&consumer, NULL); 
    } 
    while(true); 
    return 0; 
} 
void createArray(int size){ 
    if (!buffer){ 
     buffer=(int*)malloc(size*sizeof(int)); 
    } 
} 
void createProducers(int size){ 
    if (!producers){ 
     producers=(pthread_t*)malloc(size*sizeof(pthread_t*)); 
    } 
} 
void createConsumers(int size){ 
    if (!consumers){ 
     consumers=(pthread_t*)malloc(size*sizeof(pthread_t*)); 
    } 
} 
void * producer(){ 
    pthread_setcanceltype(PTHREAD_CANCEL_ASYNCHRONOUS,NULL); 
    stringstream loginfo; 
    while (running){ 
      pthread_mutex_lock(&condp_mutex); //sets mutual exclusion for the producer 
      clock_gettime(CLOCK_REALTIME,&pts); 
      loginfo<<pts.tv_nsec<<": Producer "<<pthread_self()<< "entered critical section.\n"; 
      char* logstring= createString(loginfo.str()); 
      fprintf(logFile, "%s", logstring); 
      free(logstring); 
      int item = produceItem(); 
      //down(empty); //we will have one less empty slot when this is done 
      while (empty==0){ 
       clock_gettime(CLOCK_REALTIME,&pts); 
       loginfo<<pts.tv_nsec<<": Producer "<<pthread_self()<<" encountered full buffer.\n"; 
       logstring= createString(loginfo.str()); 
       fprintf(logFile, "%s", logstring); 
       free(logstring); 
       pthread_cond_wait(&condVarProd,&condp_mutex); 
      } 
      //pthread_mutex_lock(&condp_mutex); //sets mutual exclusion for the producer 
      empty--; 
      buffer[rear]=item; 
      int rear2=rear; 
      rear=((rear+1)%BUFFER_SIZE); 
      clock_gettime(CLOCK_REALTIME,&pts); 
      loginfo<<pts.tv_nsec<<": Item created by "<<pthread_self()<<" into slot "<<rear2<<". Value: "<<item<<". \n"; 
      logstring= createString(loginfo.str()); 
      fprintf(logFile, "%s", logstring); 
      free(logstring); 
      //write to log file 
      full++; 
      pthread_cond_signal(&condVarCons); 
      clock_gettime(CLOCK_REALTIME,&pts); 
      loginfo<<pts.tv_nsec<<": Producer "<<pthread_self()<< "left critical section.\n"; 
      logstring= createString(loginfo.str()); 
      fprintf(logFile, "%s", logstring); 
      free(logstring); 

      pthread_mutex_unlock(&condp_mutex); 
      usleep(rand()%5000000); 
      //releases mutual exclusion for the producer 
     //up(full); //now that this is complete, we have one more full slot 

     //struct timespec req={(rand()%5000+1)*1000000},rem={0}; 
     //nanosleep(&req, &rem); //sleeps for 1 millisecond - 5 seconds 
    } 
} 
void* consumer(){ 
    pthread_setcanceltype(PTHREAD_CANCEL_ASYNCHRONOUS,NULL); 
    stringstream loginfo; 
    while (running){ 
     //down (&full); 
     pthread_mutex_lock(&condc_mutex); 
     clock_gettime(CLOCK_REALTIME,&cts); 
     loginfo<<cts.tv_nsec<<": Consumer "<<pthread_self()<< "entered critical section.\n"; 
     char* logstring= createString(loginfo.str()); 
     fprintf(logFile, "%s", logstring); 
     free(logstring); 
     while (full==0){ 
      clock_gettime(CLOCK_REALTIME,&cts); 
      loginfo<<cts.tv_nsec<<": Consumer "<<pthread_self()<<" encountered empty buffer.\n"; 
      logstring= createString(loginfo.str()); 
      fprintf(logFile, "%s", logstring); 
      free(logstring); 
      pthread_cond_wait(&condVarCons,&condc_mutex); 
     } 
      full--; 
      //pthread_mutex_lock(&condc_mutex); 
       int item=buffer[front]; 
       int front2=front; 
       front=((front+1)%BUFFER_SIZE); 

       clock_gettime(CLOCK_REALTIME,&cts); 
       loginfo<<cts.tv_nsec<<": Item removed by "<<pthread_self()<<" from slot "<<front2<<". Value: "<<item<<". \n"; 
       logstring= createString(loginfo.str()); 
       fprintf(logFile, "%s", logstring); 
       free(logstring); 

       //write to log file 
      empty++; 
     pthread_cond_signal(&condVarProd); 
     clock_gettime(CLOCK_REALTIME,&cts); 
     loginfo<<cts.tv_nsec<<": Consumer "<<pthread_self()<< "left critical section.\n"; 
     logstring= createString(loginfo.str()); 
     fprintf(logFile, "%s", logstring); 
     free(logstring); 
     pthread_mutex_unlock(&condc_mutex); 
     //up(&empty); 
     usleep(rand()%5000000); 
     //struct timespec req={(rand()%5000+1)*1000000},rem={0}; 
     //nanosleep(&req, &rem); //sleeps for 1 millisecond - 5 seconds 
    } 
} 
string trimspace(string str){ //trims leading and trailing space off string and returns new string 
    size_t startpos=str.find_first_not_of(" "); 
    size_t endpos=str.find_last_not_of(" "); 
    return str.substr(startpos, endpos-startpos+1); 
} 
char* createString(string str){ //converts a string to a c string using malloc 
    char* c=(char*)malloc(str.length()+1); 
    int i; 
    for (i=0;i<str.length();i++){ 
     c[i]=str[i]; 
    } 
    c[i]='\0'; 
    return c; 
} 
int produceItem(){ //creates and returns an integer (item) 
    int item= rand()%1000000+1; //random int is between 1 and 1,000,000 
    return item; 
} 
void signalHandler(int signum) 
{ 
    if (signum==SIGINT){ 
     running=false; 
     cout<<"\nEnding application... \n"; 
     fclose(logFile); 
     //int i; 

     for (i=0;i<producerCount;i++){ 
      pthread_cancel(producers[i]); 
      //pthread_join(producers[i],NULL); 

     }for (i=0;i<consumerCount;i++){ 
      pthread_cancel(consumers[i]); 
      //pthread_join(consumers[i],NULL); 
     //} 
     exit(0); 
    } 
}

在一次试用中，这在一个日志文件中产生以下内容。正如你所看到的那样，出现了重复的事件，但是就创建和删除项目的顺序（比较时间戳与线程ID，缓冲槽和存储/恢复的值）而言，它似乎工作正常：

390783278: Producer 139708484286208entered critical section. 
390783278: Producer 139708484286208entered critical section. 
391751560: Item created by 139708484286208 into slot 0. Value: 994902. 
390783278: Producer 139708484286208entered critical section. 
391751560: Item created by 139708484286208 into slot 0. Value: 994902. 
391758681: Producer 139708484286208left critical section. 
391766506: Producer 139708475893504entered critical section. 
391766506: Producer 139708475893504entered critical section. 
391788442: Item created by 139708475893504 into slot 1. Value: 452289. 
391766506: Producer 139708475893504entered critical section. 
391788442: Item created by 139708475893504 into slot 1. Value: 452289. 
391790768: Producer 139708475893504left critical section. 
391799767: Producer 139708492678912entered critical section. 
391799767: Producer 139708492678912entered critical section. 
391807766: Item created by 139708492678912 into slot 2. Value: 775797. 
391799767: Producer 139708492678912entered critical section. 
391807766: Item created by 139708492678912 into slot 2. Value: 775797. 
391809898: Producer 139708492678912left critical section. 
391815624: Producer 139708425537280entered critical section. 
391815624: Producer 139708425537280entered critical section. 
391824889: Item created by 139708425537280 into slot 3. Value: 40803. 
391815624: Producer 139708425537280entered critical section. 
391824889: Item created by 139708425537280 into slot 3. Value: 40803. 
391827189: Producer 139708425537280left critical section. 
391832787: Producer 139708442322688entered critical section. 
391832787: Producer 139708442322688entered critical section. 
391839933: Item created by 139708442322688 into slot 4. Value: 859933. 
391832787: Producer 139708442322688entered critical section. 
391839933: Item created by 139708442322688 into slot 4. Value: 859933. 
391842089: Producer 139708442322688left critical section. 
391847512: Producer 139708433929984entered critical section. 
391847512: Producer 139708433929984entered critical section. 
391857473: Item created by 139708433929984 into slot 5. Value: 862962. 
391847512: Producer 139708433929984entered critical section. 
391857473: Item created by 139708433929984 into slot 5. Value: 862962. 
391859600: Producer 139708433929984left critical section. 
391865631: Producer 139708417144576entered critical section. 
391865631: Producer 139708417144576entered critical section. 
391872901: Item created by 139708417144576 into slot 6. Value: 464855. 
391865631: Producer 139708417144576entered critical section. 
391872901: Item created by 139708417144576 into slot 6. Value: 464855. 
391874995: Producer 139708417144576left critical section. 
391880352: Producer 139708450715392entered critical section. 
391880352: Producer 139708450715392entered critical section. 
391888990: Item created by 139708450715392 into slot 7. Value: 50160. 
391880352: Producer 139708450715392entered critical section. 
391888990: Item created by 139708450715392 into slot 7. Value: 50160. 
391891063: Producer 139708450715392left critical section. 
391896778: Producer 139708459108096entered critical section. 
391896778: Producer 139708459108096entered critical section. 
391903950: Item created by 139708459108096 into slot 8. Value: 498178. 
391896778: Producer 139708459108096entered critical section. 
391903950: Item created by 139708459108096 into slot 8. Value: 498178. 
391906072: Producer 139708459108096left critical section. 
391911508: Producer 139708467500800entered critical section. 
391911508: Producer 139708467500800entered critical section. 
391920487: Item created by 139708467500800 into slot 9. Value: 917334. 
391911508: Producer 139708467500800entered critical section. 
391920487: Item created by 139708467500800 into slot 9. Value: 917334. 
391922544: Producer 139708467500800left critical section. 
391637865: Consumer 139708350002944entered critical section. 
391637865: Consumer 139708350002944entered critical section. 
391930791: Item removed by 139708350002944 from slot 0. Value: 994902. 
391637865: Consumer 139708350002944entered critical section. 
391930791: Item removed by 139708350002944 from slot 0. Value: 994902. 
391933158: Consumer 139708350002944left critical section. 
391967700: Consumer 139708358395648entered critical section. 
391967700: Consumer 139708358395648entered critical section. 
391976740: Item removed by 139708358395648 from slot 1. Value: 452289. 
391967700: Consumer 139708358395648entered critical section. 
391976740: Item removed by 139708358395648 from slot 1. Value: 452289. 
391978960: Consumer 139708358395648left critical section. 
391984926: Consumer 139708341610240entered critical section. 
391984926: Consumer 139708341610240entered critical section. 
391994663: Item removed by 139708341610240 from slot 2. Value: 775797. 
391984926: Consumer 139708341610240entered critical section. 
391994663: Item removed by 139708341610240 from slot 2. Value: 775797. 
391996774: Consumer 139708341610240left critical section. 
392002719: Consumer 139708366788352entered critical section. 
392002719: Consumer 139708366788352entered critical section. 
392009664: Item removed by 139708366788352 from slot 3. Value: 40803. 
392002719: Consumer 139708366788352entered critical section. 
392009664: Item removed by 139708366788352 from slot 3. Value: 40803. 
392011765: Consumer 139708366788352left critical section. 
392017278: Consumer 139708375181056entered critical section. 
392017278: Consumer 139708375181056entered critical section. 
392026094: Item removed by 139708375181056 from slot 4. Value: 859933. 
392017278: Consumer 139708375181056entered critical section. 
392026094: Item removed by 139708375181056 from slot 4. Value: 859933. 
392028216: Consumer 139708375181056left critical section. 
392034061: Consumer 139708383573760entered critical section. 
392034061: Consumer 139708383573760entered critical section. 
392036228: Item removed by 139708383573760 from slot 5. Value: 862962. 
392034061: Consumer 139708383573760entered critical section. 
392036228: Item removed by 139708383573760 from slot 5. Value: 862962. 
392041046: Consumer 139708383573760left critical section. 
392046521: Consumer 139708408751872entered critical section. 
392046521: Consumer 139708408751872entered critical section. 
392048239: Item removed by 139708408751872 from slot 6. Value: 464855. 
392046521: Consumer 139708408751872entered critical section. 
392048239: Item removed by 139708408751872 from slot 6. Value: 464855. 
392050158: Consumer 139708408751872left critical section. 
392054579: Consumer 139708400359168entered critical section. 
392054579: Consumer 139708400359168entered critical section. 
392056109: Item removed by 139708400359168 from slot 7. Value: 50160. 
392054579: Consumer 139708400359168entered critical section. 
392056109: Item removed by 139708400359168 from slot 7. Value: 50160. 
392058047: Consumer 139708400359168left critical section. 
392062556: Consumer 139708391966464entered critical section. 
392062556: Consumer 139708391966464entered critical section. 
392064062: Item removed by 139708391966464 from slot 8. Value: 498178. 
392062556: Consumer 139708391966464entered critical section. 
392064062: Item removed by 139708391966464 from slot 8. Value: 498178. 
392065952: Consumer 139708391966464left critical section. 
392070444: Consumer 139708333217536entered critical section. 
392070444: Consumer 139708333217536entered critical section. 
392071917: Item removed by 139708333217536 from slot 9. Value: 917334. 
392070444: Consumer 139708333217536entered critical section. 
392071917: Item removed by 139708333217536 from slot 9. Value: 917334. 
392073850: Consumer 139708333217536left critical section. 
392017278: Consumer 139708375181056entered critical section. 
392026094: Item removed by 139708375181056 from slot 4. Value: 859933. 
392028216: Consumer 139708375181056left critical section. 
537760776: Consumer 139708375181056entered critical section. 
392017278: Consumer 139708375181056entered critical section. 
392026094: Item removed by 139708375181056 from slot 4. Value: 859933. 
392028216: Consumer 139708375181056left critical section. 
537760776: Consumer 139708375181056entered critical section. 
537779758: Consumer 139708375181056 encountered empty buffer. 
392070444: Consumer 139708333217536entered critical section. 
392071917: Item removed by 139708333217536 from slot 9. Value: 917334. 
392073850: Consumer 139708333217536left critical section. 
818759131: Consumer 139708333217536entered critical section. 
392070444: Consumer 139708333217536entered critical section. 
392071917: Item removed by 139708333217536 from slot 9. Value: 917334. 
392073850: Consumer 139708333217536left critical section. 
818759131: Consumer 139708333217536entered critical section. 
818777830: Consumer 139708333217536 encountered empty buffer. 
391832787: Producer 139708442322688entered critical section. 
391839933: Item created by 139708442322688 into slot 4. Value: 859933. 
391842089: Producer 139708442322688left critical section. 
104776263: Producer 139708442322688entered critical section. 
391832787: Producer 139708442322688entered critical section. 
391839933: Item created by 139708442322688 into slot 4. Value: 859933. 
391842089: Producer 139708442322688left critical section. 
104776263: Producer 139708442322688entered critical section. 
104794865: Item created by 139708442322688 into slot 10. Value: 729187. 
391832787: Producer 139708442322688entered critical section. 
391839933: Item created by 139708442322688 into slot 4. Value: 859933. 
391842089: Producer 139708442322688left critical section. 
104776263: Producer 139708442322688entered critical section. 
104794865: Item created by 139708442322688 into slot 10. Value: 729187. 
104804537: Producer 139708442322688left critical section. 
392017278: Consumer 139708375181056entered critical section. 
392026094: Item removed by 139708375181056 from slot 4. Value: 859933. 
392028216: Consumer 139708375181056left critical section. 
537760776: Consumer 139708375181056entered critical section. 
537779758: Consumer 139708375181056 encountered empty buffer. 
104823321: Item removed by 139708375181056 from slot 10. Value: 729187. 
392017278: Consumer 139708375181056entered critical section. 
392026094: Item removed by 139708375181056 from slot 4. Value: 859933. 
392028216: Consumer 139708375181056left critical section. 
537760776: Consumer 139708375181056entered critical section. 
537779758: Consumer 139708375181056 encountered empty buffer. 
104823321: Item removed by 139708375181056 from slot 10. Value: 729187. 
104838395: Consumer 139708375181056left critical section. 
392054579: Consumer 139708400359168entered critical section. 
392056109: Item removed by 139708400359168 from slot 7. Value: 50160. 
392058047: Consumer 139708400359168left critical section. 
305774914: Consumer 139708400359168entered critical section. 
392054579: Consumer 139708400359168entered critical section. 
392056109: Item removed by 139708400359168 from slot 7. Value: 50160. 
392058047: Consumer 139708400359168left critical section. 
305774914: Consumer 139708400359168entered critical section. 
305793885: Consumer 139708400359168 encountered empty buffer. 
392002719: Consumer 139708366788352entered critical section. 
392009664: Item removed by 139708366788352 from slot 3. Value: 40803. 
392011765: Consumer 139708366788352left critical section. 
380742045: Consumer 139708366788352entered critical section. 
392002719: Consumer 139708366788352entered critical section. 
392009664: Item removed by 139708366788352 from slot 3. Value: 40803. 
392011765: Consumer 139708366788352left critical section. 
380742045: Consumer 139708366788352entered critical section. 
380755715: Consumer 139708366788352 encountered empty buffer. 
391865631: Producer 139708417144576entered critical section. 
391872901: Item created by 139708417144576 into slot 6. Value: 464855. 
391874995: Producer 139708417144576left critical section. 
530764064: Producer 139708417144576entered critical section. 
391865631: Producer 139708417144576entered critical section. 
391872901: Item created by 139708417144576 into slot 6. Value: 464855. 
391874995: Producer 139708417144576left critical section. 
530764064: Producer 139708417144576entered critical section. 
530783146: Item created by 139708417144576 into slot 11. Value: 697827. 
391865631: Producer 139708417144576entered critical section. 
391872901: Item created by 139708417144576 into slot 6. Value: 464855. 
391874995: Producer 139708417144576left critical section. 
530764064: Producer 139708417144576entered critical section. 
530783146: Item created by 139708417144576 into slot 11. Value: 697827. 
530838023: Producer 139708417144576left critical section. 
392070444: Consumer 139708333217536entered critical section. 
392071917: Item removed by 139708333217536 from slot 9. Value: 917334. 
392073850: Consumer 139708333217536left critical section. 
818759131: Consumer 139708333217536entered critical section. 
818777830: Consumer 139708333217536 encountered empty buffer. 
530848657: Item removed by 139708333217536 from slot 11. Value: 697827. 
392070444: Consumer 139708333217536entered critical section. 
392071917: Item removed by 139708333217536 from slot 9. Value: 917334. 
392073850: Consumer 139708333217536left critical section. 
818759131: Consumer 139708333217536entered critical section. 
818777830: Consumer 139708333217536 encountered empty buffer. 
530848657: Item removed by 139708333217536 from slot 11. Value: 697827. 
530861640: Consumer 139708333217536left critical section. 
392070444: Consumer 139708333217536entered critical section. 
392071917: Item removed by 139708333217536 from slot 9. Value: 917334. 
392073850: Consumer 139708333217536left critical section. 
818759131: Consumer 139708333217536entered critical section. 
818777830: Consumer 139708333217536 encountered empty buffer. 
530848657: Item removed by 139708333217536 from slot 11. Value: 697827. 
530861640: Consumer 139708333217536left critical section. 
931760566: Consumer 139708333217536entered critical section. 
392070444: Consumer 139708333217536entered critical section. 
392071917: Item removed by 139708333217536 from slot 9. Value: 917334. 
392073850: Consumer 139708333217536left critical section. 
818759131: Consumer 139708333217536entered critical section. 
818777830: Consumer 139708333217536 encountered empty buffer. 
530848657: Item removed by 139708333217536 from slot 11. Value: 697827. 
530861640: Consumer 139708333217536left critical section. 
931760566: Consumer 139708333217536entered critical section. 
931779060: Consumer 139708333217536 encountered empty buffer. 
391766506: Producer 139708475893504entered critical section. 
391788442: Item created by 139708475893504 into slot 1. Value: 452289. 
391790768: Producer 139708475893504left critical section. 
965818384: Producer 139708475893504entered critical section. 
391766506: Producer 139708475893504entered critical section. 
391788442: Item created by 139708475893504 into slot 1. Value: 452289. 
391790768: Producer 139708475893504left critical section. 
965818384: Producer 139708475893504entered critical section. 
965837852: Item created by 139708475893504 into slot 12. Value: 690947. 
391766506: Producer 139708475893504entered critical section. 
391788442: Item created by 139708475893504 into slot 1. Value: 452289. 
391790768: Producer 139708475893504left critical section.

本质上，只要我写入文件就会出现问题。例如，该代码生成日志文件的第一耦合线将如下所示：

pthread_mutex_lock(&condp_mutex); //sets mutual exclusion for the producer 
clock_gettime(CLOCK_REALTIME,&pts); 
loginfo<<pts.tv_nsec<<": Producer "<<pthread_self()<< "entered critical section.\n"; 
char* logstring= createString(loginfo.str()); 
fprintf(logFile, "%s", logstring); 
free(logstring);

在这种情况下，LOGINFO是后来转换为字符串，其然后被放置到日志文件的流。理论上，这个代码应该只对每个条目执行一次（由互斥锁定指定），但是它会多次打印到日志文件中。

来源

2013-10-26 Don

+2

我建议您尝试简化问题并详细说明您拥有的问题以及您想实现的目标。我怀疑有人愿意通过这段代码来猜测你正在尝试做什么。 – FKaria

回答

1

您遇到的问题是loginfo在循环迭代开始时创建，直到下一次循环迭代时才会被清除。从你的代码：

loginfo<<pts.tv_nsec<<": Producer "<<pthread_self()<< "entered critical section.\n"; 
char* logstring= createString(loginfo.str()); 
fprintf(logFile, "%s", logstring);

此代码拷贝loginfo.str()到logstring，但loginfo对象没有被清除。它仍然包含在其中的消息。

390783278: Producer 139708484286208entered critical section.

稍后，该消息被追加到：

loginfo<<pts.tv_nsec<<": Producer "<<pthread_self()<<" encountered full buffer.\n";

现在loginfo对象现在具有消息：

390783278: Producer 139708484286208entered critical section. 
391751560: Item created by 139708484286208 into slot 0. Value: 994902.

此重复，直至下一个循环迭代。即时修复是后每次调用fprintf是清除流：

loginfo.str("");

然而，一个更好的解决办法是从stringstream更改为ofstream这将直接输出到文件中。在使用文件流时，无需调用fprintf或复制字符串。

来源

2013-10-26 06:28:50 Steve

相关问题

 相关问题