Дублирование выходного файла журнала производителя-потребителя

У меня возникают некоторые проблемы с моей реализацией проблемы производитель-потребитель. Похоже, что он работает нормально, но когда я выполнил файл журнала для захвата критических событий, я понял, что произошло некоторое дублирование событий. Это связано с тем, что манипуляции с файлами не являются взаимоисключающими или есть что-то еще, что может вызвать это? Я запускаю код на Ubuntu 12.04 VM.

#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);
    }
}

Это вызвало следующее в одном файле журнала на одном испытании. Как вы видите, появляются повторяющиеся события, но, похоже, он работает нормально, поскольку порядок создания и удаления элементов (сравнение временных меток с идентификатором потока, слотом буфера и сохраненным/восстановленным значением):

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.

По сути, проблема возникает, когда я пишу в файл. Например, код, генерирующий первые пару строк файла журнала, будет выглядеть следующим образом:

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);

В этом случае loginfo - это поток, который затем преобразуется в строку, которая затем помещается в файл журнала. Теоретически этот код должен выполняться только один раз за каждый вход в критический раздел (обозначенный блокировкой мьютекса), но он несколько раз печатается в файле журнала.