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main当函数尝试多次运行某个类（Rock）并出现double free or corruptionglibc 错误时，我的程序退出。

Valgrind 返回：

==18672== Conditional jump or move depends on uninitialised value(s)
==18672==    at 0x56F8554: std::ostreambuf_iterator<char, std::char_traits<char> > std::num_put<char, std::ostreambuf_iterator<char, std::char_traits<char> > >::_M_insert_int<unsigned long>(std::ostreambuf_iterator<char, std::char_traits<char> >, std::ios_base&, char, unsigned long) const (in /usr/lib64/libstdc++.so.6.0.17)
==18672==    by 0x56F876C: std::num_put<char, std::ostreambuf_iterator<char, std::char_traits<char> > >::do_put(std::ostreambuf_iterator<char, std::char_traits<char> >, std::ios_base&, char, unsigned long) const (in /usr/lib64/libstdc++.so.6.0.17)
==18672==    by 0x56FB945: std::ostream& std::ostream::_M_insert<unsigned long>(unsigned long) (in /usr/lib64/libstdc++.so.6.0.17)
==18672==    by 0x431515: Rock::saveClustering(std::set<Attribution, std::less<Attribution>, std::allocator<Attribution> >) (rock.cpp:1406)
==18672==    by 0x430C66: Rock::startRock() (rock.cpp:1321)
==18672==    by 0x45DABC: main (main.cpp:207)
==18672==  Uninitialised value was created by a stack allocation
==18672==    at 0x42FF39: Rock::getFinalList(std::vector<Rock::BestLabel, std::allocator<Rock::BestLabel> >&) (rock.cpp:1139)
==18672== 
==18672== 
==18672== HEAP SUMMARY:
==18672==     in use at exit: 292 bytes in 11 blocks
==18672==   total heap usage: 86,558 allocs, 86,547 frees, 21,133,326 bytes allocated
==18672== 
==18672== 292 (52 direct, 240 indirect) bytes in 1 blocks are definitely lost in loss record 11 of 11
==18672==    at 0x4C2BCFB: malloc (vg_replace_malloc.c:270)
==18672==    by 0x5F7FC94: nss_parse_service_list (in /lib64/libc-2.15.so)
==18672==    by 0x5F80173: __nss_database_lookup (in /lib64/libc-2.15.so)
==18672==    by 0xC1C15DB: ???
==18672==    by 0x5F3592B: getpwuid_r@@GLIBC_2.2.5 (in /lib64/libc-2.15.so)
==18672==    by 0x5050638: pqGetpwuid (in /opt/postgres_home/lib/libpq.so.5.3)
==18672==    by 0x503C3BD: pqGetHomeDirectory (in /opt/postgres_home/lib/libpq.so.5.3)
==18672==    by 0x503CCD4: getPgPassFilename (in /opt/postgres_home/lib/libpq.so.5.3)
==18672==    by 0x503F78A: PasswordFromFile (in /opt/postgres_home/lib/libpq.so.5.3)
==18672==    by 0x503FAAB: connectOptions2 (in /opt/postgres_home/lib/libpq.so.5.3)
==18672==    by 0x503FD77: PQconnectStart (in /opt/postgres_home/lib/libpq.so.5.3)
==18672==    by 0x503FDA5: PQconnectdb (in /opt/postgres_home/lib/libpq.so.5.3)
==18672== 
==18672== LEAK SUMMARY:
==18672==    definitely lost: 52 bytes in 1 blocks
==18672==    indirectly lost: 240 bytes in 10 blocks
==18672==      possibly lost: 0 bytes in 0 blocks
==18672==    still reachable: 0 bytes in 0 blocks
==18672==         suppressed: 0 bytes in 0 blocks

我不习惯瓦尔格林。postgres它是否说在数据库访问方面存在未释放的未初始化内存？我用来获取数据的方法是：

void Comum::fetchDB ( string sql_statement )
{
    string conn_str ( "dbname=" + getDbName() + " user=" + getDbUser() );
    pqxx::connection conn (conn_str);
    pqxx::work txn (conn);              // ex: domain = "voice"
    pqxx::result r = txn.exec (sql_statement);

    if ( r.size () == 0 ) {
        std::cerr << "No records found for '" << domain << "'." << endl;
        exit (12);
    }

    txn.commit ();

    for (unsigned int u = 0; u != getNrFields (); ++u) {
        vector <string> v;
        v.reserve (r.size());
        db_fetched.push_back (v);
    }

    for (unsigned int rownum = 0; rownum != r.size(); ++rownum) {
        const pqxx::result::tuple row = r[rownum];

        for (unsigned int colnum = 0; colnum != row.size(); ++colnum) {
            const pqxx::result::field f = row[colnum];
            db_fetched [colnum].push_back( f.c_str() );
        }
    }
    conn.disconnect();
}

关于 Valgrind 输出的第一行，Conditional jump or move depends on unitialized value(s)方法saveClustering如下：

void Rock::saveClustering (const set<Attribution> result)
{
    string rock_dir = "rock";
    string parent_dir = "output";
    string dir = parent_dir + "/" + rock_dir;

    // Create directory.
    createDir (parent_dir);
    createDir (dir);

    // Build filename.
    string filename;

    map<unsigned int, AttType>::const_iterator citype = att_type.begin();
    while (citype != att_type.end()) {
        filename += citype->second.getName();
        if (++citype != att_type.end()) {
            filename += "-";
        }
    }

    filename = parent_dir + "/" + rock_dir + "/" + filename + "-" + currentDateTime() + ".txt";
    ofstream myfile(filename.c_str());

    if (myfile.is_open()) {
        for ( set<Attribution>::const_iterator ci = result.begin();ci != result.end(); ++ci ) {
            myfile << ci->id << "\t";

            for (vector<unsigned int>::const_iterator enci = ci->encodings.begin(); enci != ci->encodings.end(); ++enci) {
                myfile << *enci << "\t";
            }

            myfile << ci->type << "\t" << ci->assignment << endl;  // 1406 LINE
        }
        myfile << endl;
        myfile.close();

    } else {
        cerr << "It was not possible to save decoder filename " << filename << endl;
        cerr << "Press any key <ENTER> to continue.";
    }
}

我只是看不出有什么问题，也无法提供一个小的可行程序。

4

1 回答 1

1

输出中有两个单独的问题valgrind。

第一个是使用未初始化的内存，它告诉你是在堆栈上创建rock.cpp的1139

==18672==    at 0x42FF39: Rock::getFinalList(std::vector<Rock::BestLabel, std::allocator<Rock::BestLabel> >&) (rock.cpp:1139)

查看该行并初始化变量。

第二个问题是内存泄漏，显然来自 Postgres API。这几乎肯定不是你崩溃的原因。

这些看起来都不像导致双重释放错误的原因，这很可能是由于未在您的类中实现正确的复制构造函数或复制赋值运算符造成的。

于 2013-01-16T00:31:23.270 回答