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我正在使用一个硬件模拟器，它使用 PIN 工具来执行工作负载。作为工作量，我使用以下代码。尽管它可以在带有-lpthread标志的 Ubuntu 上运行，但在加入线程时它会在模拟器上冻结。

我认为本机操作系统可以容忍但模拟器不能容忍此代码中有一些不安全的东西。对此进行编码的最合适方法是什么？

主.h：

#include <stdlib.h>
#include <iostream>
#include <fstream>
#include <string>
#include <pthread.h>
#include <stdint.h>
#include <getopt.h>
#include <set>
#include <vector>
#include <algorithm>
#include <iterator>

#define NUM_OF_VERTICES 4
#define NUM_OF_PTHREADS (NUM_OF_VERTICES*(NUM_OF_VERTICES-1)/2)

std::string payload_texts[NUM_OF_VERTICES];
void payload_text_initialize();
double indices [NUM_OF_VERTICES][NUM_OF_VERTICES];

class thread_args {   
    public: 
        uint index1, index2;
        unsigned  long value = 0;
        unsigned  long * valuePointer = &value;
};

主.cc：

#include "main.h"

extern "C" {
    extern void mcsim_skip_instrs_begin();
    extern void mcsim_skip_instrs_end();
    extern void mcsim_spinning_begin();
    extern void mcsim_spinning_end();
    int32_t log_2(uint64_t);
}

using namespace std;

set<char> find_uniques(string str){
    set<char> unique_chars;
    for (int i = 0 ; i < str.length() ; i++ ){
        char c = str.at(i);
        if (unique_chars.find(c) == unique_chars.end())
            unique_chars.insert(c);
    }
    return unique_chars;
}

void * jaccard_visit(void *arg){
    thread_args * args = (thread_args *) arg;
    set<char> setunion;
    set<char> intersect;

    set<char> set1 = find_uniques(payload_texts[args->index1]);
    set<char> set2 = find_uniques(payload_texts[args->index2]);


    std::set_intersection(set1.begin(),set1.end(),set2.begin(),set2.end(),std::inserter(intersect,intersect.begin()));
    std::set_union(set1.begin(),set1.end(),set2.begin(),set2.end(),std::inserter(setunion,setunion.begin()));

    double similarity = ((double) intersect.size()) / ((double) setunion.size());
    indices[args->index1][args->index2] = similarity;
    indices[args->index2][args->index1] = similarity;

    unsigned long a = 1;
    unsigned long b = 1;
    unsigned long c = a + b;
    for (int i = 3 ; i < 100000 * (similarity - 0.9) ; i++){
        a = b;
        b = c; 
        c = a + b;
    }

    *(args->valuePointer) = c;

    return NULL;
}

void execute_parallel(){      
    pthread_t threads[NUM_OF_PTHREADS]; //array to hold thread information 
    thread_args *th_args = (thread_args*) malloc(NUM_OF_PTHREADS * sizeof(thread_args)); 

    cout << "NUM_OF_PTHREADS is " << NUM_OF_PTHREADS << endl;
    uint k = 0 ;
    for (int i = 0 ; i < NUM_OF_VERTICES ; i++){
        for (int j = i+1 ; j < NUM_OF_VERTICES ; j++){
            th_args[k].index1 = i;
            th_args[k].index2 = j;
            th_args[k].value = i+j; 
            th_args[k].valuePointer = &(th_args[k].value);
            pthread_create(&threads[k], NULL, jaccard_visit, (void*) &th_args[k]);
            cout << "Thread " << k << " is started" << endl;
            k++;
        }
    }

    cout << "k is " << k << endl;

    for(int i = 0; i < NUM_OF_PTHREADS; i++){ 
        cout << "Thread " << i << " is joined" << endl;
        pthread_join(threads[i], NULL); 
    } 

    cout << "Free threads" << endl ;

    free(th_args); 

} 

void manual_schedule(){
    pthread_t th0, th1, th2, th3, th4, th5;
    thread_args arg0, arg1, arg2, arg3, arg4, arg5;

    arg0.index1 = 0;    arg0.index2 = 1;    arg0.value = 0; arg0.valuePointer = &arg0.value;
    arg1.index1 = 0;    arg1.index2 = 2;    arg1.value = 1; arg1.valuePointer = &arg1.value;
    arg2.index1 = 0;    arg2.index2 = 3;    arg2.value = 2; arg2.valuePointer = &arg2.value;
    arg3.index1 = 1;    arg3.index2 = 2;    arg3.value = 3; arg3.valuePointer = &arg3.value;
    arg4.index1 = 1;    arg4.index2 = 3;    arg4.value = 4; arg4.valuePointer = &arg4.value;
    arg5.index1 = 2;    arg5.index2 = 3;    arg5.value = 5; arg5.valuePointer = &arg5.value;

    cout << "Arguments are done ";

    pthread_create(&th0, NULL, jaccard_visit, (void*) &arg0);
    pthread_create(&th1, NULL, jaccard_visit, (void*) &arg1);
    pthread_create(&th2, NULL, jaccard_visit, (void*) &arg2);
    pthread_create(&th3, NULL, jaccard_visit, (void*) &arg3);
    pthread_create(&th4, NULL, jaccard_visit, (void*) &arg4);
    pthread_create(&th5, NULL, jaccard_visit, (void*) &arg5);

    cout << "Threads are created" << endl;

    cout << "Join starts here" << endl;
    pthread_join(th0, NULL); 
    pthread_join(th1, NULL); 
    pthread_join(th2, NULL); 
    pthread_join(th3, NULL); 
    pthread_join(th4, NULL); 
    pthread_join(th5, NULL); 

    cout << "Fibonaccis: " <<endl;
    cout << *(arg0.valuePointer) << endl;
    cout << *(arg1.valuePointer) << endl;
    cout << *(arg2.valuePointer) << endl;
    cout << *(arg3.valuePointer) << endl;
    cout << *(arg4.valuePointer) << endl;
    cout << *(arg5.valuePointer) << endl;
}

int main(int argc, const char * argv[]){
    cout << "Jaccard process is started"<<endl;
    mcsim_skip_instrs_begin();
    payload_text_initialize();
    mcsim_skip_instrs_end();

    cout << "Parallel part begins"<< endl;
    manual_schedule();

    cout << "Calculated results are being logged"<<endl;
    for (int i = 0 ; i < NUM_OF_VERTICES ; i++){
        for (int j = 0 ; j < NUM_OF_VERTICES ; j++){
            cout << indices[i][j] << " ";
        }
        cout << endl;
    }
}



void payload_text_initialize(){
    payload_texts[0] = "l5IC5uC9AzcROkE3YkDJ2lEzLts8XP8a9WqDgDLWjg1M7HysAUfDFwzLWjc7875PnZVUHLzi6nQaUMQDNUeG4Wn2UkiOB79tOlE1t6LaKYbYiCJwJ34CAOFZCIbFSmcLTAAoB1rvPfeA6oM3kV3C8BDvraGvXjUORLGFAcBRQCerb3WD0qhrrM0MVW0t93bBqlTsrkxg";
    payload_texts[1] = "tILKwAhbUkoqouKZ1G1VrZRmKwQnwzBgQirLkdedsYIAplKdEfk8oSmqdJmCJd5g0Q3VcJ8RYoxtIwA7jL1L01DcagIOuld0whcyM0yvSP0pMWO2yVTwOQPGkW2k7AHqzSEvb5BWkKsTexBsCUepjbG50T6vKsEHXGJ9aZwn2274Ekhnu1hlvuTqsS8jgwr0kQwhbwxN";
    payload_texts[2] = "LNyQgx3mox3szmRNn1tSB4ibVuLsTr7MfANlj41Y0hKStx3NJx1O52XxNiqTMDCu4eGwWYcBvFMEC5tl1E7Rsm0Q9NZsPAJIwuiPYQuXeUyhMmbFiwRk6PlziXne0QaFJ3TrncsHsL3LxIDyaDPScSRdEvX72IJmi2gQTHgASi0KkKH4Sr6VJV3FjdNjKwY2ncT5oSXZ";
    payload_texts[3] = "UxynTAvEWF4CcY9wUJRFnrX7sgrvvubcXUqH5DXK12UjSHDUME397S3BdB38FeMQJq8r7P7RILAY0qkw7OxUhGsZHRPmuY7VwKULqb6fx0Oy2McW2u07yqdAEMCN6AkQ1jTn2sXB4uWH21uLbjCf9i2V7W9tyw3cx6piE7XJb3vfbLI34OG5LKQXmVAGT0D6nbibaN8M";
}

execute_parallel()包含 2 个用于创建和连接 pthread 的 for 循环。manual_schedule()具有相同代码的展开版本。在 PIN 上执行时，两者都运行良好，直到第一个线程的连接函数。当加入来时，它会冻结并永远保持这种状态，没有任何信号或错误。在带有-lpthread标志的 Ubuntu 上执行时，它可以完美运行并生成结果。

在这种情况下实现 pthread 的最安全和最合适的方法是什么？

提前致谢

编辑

我注意到程序在阅读之前冻结payload_texts[args->index1]。添加互斥锁有助于在这一点上继续进行。它也正常工作了一次。现在它是不确定的，在同一个二进制文件的多次执行中，它很少能正确完成。我认为应该是 jaccard_visit 函数内部出现死锁的原因。我将其更改如下：

void * jaccard_visit(void *arg){
    thread_args * args = (thread_args *) arg;
    set<char> setunion;
    set<char> intersect;
    int id = args->index1 * 10 + args->index2;

    pthread_mutex_lock(&cout_mutex);    cout << "Thread "<< id << " started with indices: " << args->index1 << " " << args->index2 << endl;     pthread_mutex_unlock(&cout_mutex);

    pthread_mutex_lock(&payload_mutex);
    set<char> set1 = find_uniques(payload_texts[args->index1]);
    set<char> set2 = find_uniques(payload_texts[args->index2]);
    pthread_mutex_unlock(&payload_mutex);

    pthread_mutex_lock(&cout_mutex);    cout << id << " : payload_texts were read" << endl;         pthread_mutex_unlock(&cout_mutex);
    pthread_mutex_lock(&cout_mutex);    cout << id << " : intersect was created, scan begins" << endl;         pthread_mutex_unlock(&cout_mutex);
    for (set<char>::iterator i = set1.begin(); i != set1.end(); i++) {
        char c1 = *i;
        for (set<char>::iterator j = set2.begin(); j != set2.end(); j++) {
            char c2 = *j;
            if (c1 == c2){
                intersect.insert(c1);
                pthread_mutex_lock(&cout_mutex);    cout << id << " : char" << c1 << " was inserted to intersection" << endl;         pthread_mutex_unlock(&cout_mutex);
                break;
            }
        }
    }
    pthread_mutex_lock(&cout_mutex);    cout << id << " : intersection is calculated" << endl;     pthread_mutex_unlock(&cout_mutex);
    for (set<char>::iterator i = set1.begin(); i != set1.end(); i++) {
        setunion.insert(*i);
    }
    for (set<char>::iterator i = set2.begin(); i != set2.end(); i++) {
        char c = *i;
        bool exists = false;
        for (set<char>::iterator j = set1.begin(); j != set1.end(); j++) {
            if (c == *j)
                exists = true;
        }
        if (exists == false)
            setunion.insert(c);
    }
    pthread_mutex_lock(&cout_mutex);    cout << id << " : union is calculated" << endl;            pthread_mutex_unlock(&cout_mutex);


    double similarity = ((double) intersect.size()) / ((double) setunion.size());
    pthread_mutex_lock(&cout_mutex);
    cout << id << " : similarity is calculated as " << similarity << endl;
    pthread_mutex_unlock(&cout_mutex);
    indices[args->index1][args->index2] = similarity;
    indices[args->index2][args->index1] = similarity;

    unsigned long a = 1;
    unsigned long b = 1;
    unsigned long c = a + b;

    pthread_mutex_lock(&cout_mutex);
    cout << id << " : fibonacci starts" << endl;
    pthread_mutex_unlock(&cout_mutex);

    for (int i = 3 ; i < 100000 * (similarity - 0.9) ; i++){
        a = b;
        b = c; 
        c = a + b;
    }
    *(args->valuePointer) = c;

    //pthread_exit(args->valuePointer);
    return NULL;
}
4

1 回答 1

1

最后，我通过在每个线程执行的函数（jaccard_visit）中进行以下修改使其工作：

  1. 使用 mutex_lock 包装全局变量的读取操作
  2. 删除函数调用并内联实现它们
  3. 避免使用 set，而是使用字符串或字符数组
  4. 分离字符串函数的目标和源

以下代码运行良好：

void * jaccard_visit(void *arg){
    thread_args * args = (thread_args *) arg;
    int id = args->id;
    pthread_mutex_lock(&cout_mutex);    cout << id << " : thread started" << endl;    pthread_mutex_unlock(&cout_mutex);

    pthread_mutex_lock(&payload_mutex);
    string str1 = my_graph[args->index1].payload_text;
    string str2 = my_graph[args->index2].payload_text;
    pthread_mutex_unlock(&payload_mutex);

    pthread_mutex_lock(&cout_mutex);    cout << id << " : payload texts are read" << endl;    pthread_mutex_unlock(&cout_mutex);

    int stringLength = str1.length() - 1;
    for (int i = 0; i < stringLength; i++) {
        for (int j = i + 1; j < stringLength;) {
            if (str1[i] == str1[j]) 
                str1[j] = str1[--stringLength];
            else   
                j++;
        }
    }
    string set1 = str1.substr(0, stringLength);

    pthread_mutex_lock(&cout_mutex);    cout << id << " : unique chars of first node were extracted" << endl;    pthread_mutex_unlock(&cout_mutex);

    stringLength = str2.length() - 1;
    for (int i = 0; i < stringLength; i++) {
        for (int j = i + 1; j < stringLength;) {
            if (str2[i] == str2[j]) 
                str2[j] = str2[--stringLength];
            else   
                j++;
        }
    }
    string set2 = str2.substr(0, stringLength);

    pthread_mutex_lock(&cout_mutex);    cout << id << " : unique chars of second node were extracted" << endl;    pthread_mutex_unlock(&cout_mutex);

    int intersection_index = 0;
    int union_index = 0;
    for (int i = 0 ; i < set1.length() ; i++){
        bool exists_in_set2 = false;
        for (int j = 0 ; j < set2.length() && exists_in_set2 == false; j++){
            if (set1[i] == set2[j]) {
                intersection_index ++;
                exists_in_set2 = true;
            }
        }
        if (!exists_in_set2) {
            union_index ++;
        }       
    }
    union_index += set2.length();

    pthread_mutex_lock(&cout_mutex);  cout << id << " : set1={" << set1 << "}, set2={" << set2 << "}" << endl;    pthread_mutex_unlock(&cout_mutex);
    pthread_mutex_lock(&cout_mutex);  cout << id << " : |n|=" << intersection_index << ", |u|=" << union_index <<  endl;    pthread_mutex_unlock(&cout_mutex);

    double similarity = ((double) intersection_index / union_index); 
    pthread_mutex_lock(&cout_mutex); cout<<id<<" : similarity is: " << similarity << endl;    pthread_mutex_unlock(&cout_mutex);

    pthread_mutex_lock(&indices_mutex); 
    my_graph[args->index1].jaccardList[args->index2] = similarity;
    my_graph[args->index2].jaccardList[args->index1] = similarity;
    pthread_mutex_unlock(&indices_mutex); 
    return NULL;

}
于 2015-08-27T15:44:13.960 回答