QThread crashes the program? - multithreading

Question

I implement QThread like this, but get program crashed when it runs.
I've searched and seen posts saying it is not the correct way to use QThread.
But I cannot find any reason for the crashes of my program, what I do is only
triggering 'on_Create_triggered()' and I guarantee the mutex is locked and unlocked properly.
I have tested the program for two days(testing only by 'std::cerr << ...;' prints results), but still cannot find reason. What I guess is that the thread may wait for the lock too long and cause program to crash. (not sounds reasonable...) :)
My codes:
Background.h
class Background : public QThread
{
Q_OBJECT
public:
Background(int& val,DEVMAP& map, QQueue<LogInfoItem*>& queue, QList<DEV*>& devlist, QList<IconLabel*>& icllist,QMutex& m)
:val_i(val),DevMap(map), LogInfoQueue(queue), DevInfoList(devlist), IconLabelList(icllist),mutex(m)
{}
~Background();
protected:
void run(void);
private:
DEVMAP& DevMap;
QQueue<LogInfoItem*>&LogInfoQueue;
QList<DEV*>& DevInfoList;
QList<IconLabel*>& IconLabelList;
int& val_i;
QMutex& mutex;
void rcv();
};
Background.cpp
#include "background.h"
Background::~Background()
{
LogFile->close();
}
void Background::run(void)
{
initFile();
while(1)
{
msleep(5);
rcv();
}
}
void Background::rcv()
{
mutex.lock();
...
...//access DevMap, LogInfoQueue, DevInfoList, IconLabelList and val_i;
...
mutex.unlock();
}
MainWindow:(MainWindow has Background* back as property)
void MainWindow::initThread()
{
back = new Background(val_i, dev_map, logDisplayQueue, devInfoList, iconLabelList, mutex);
back->start();
}
void MainWindow::on_Create_triggered()
{
mutex.lock();
...
...//access DevMap, LogInfoQueue, DevInfoList, IconLabelList and val_i;
...
mutex.unlock();
}

Answer 1

I have found the reason, which is more subtle.
(I use some codes written by others but believe it is not broken, what I got totally wrong! :) )
The broken codes:
#define DATABUFLEN 96
typedef struct Para//totally 100bytes
{
UINT8 type;
UINT8 len;
UINT8 inType;
UINT8 inLen;
UINT8 value[DATABUFLEN];//96 bytes here
}ERRORTLV;
class BitState
{
public:
UINT8 dataBuf[DATABUFLEN];
......
};
And the function using it:
bool BitState::rcvData() //the function crosses bound of array
{
UINT8 data[12] =
{
0x72, 0x0A, 0x97, 0x08,
0x06, 0x0A, 0x0C, 0x0F,
0x1E, 0x2A, 0x50, 0x5F,
}; //only 12 bytes
UINT32 dataLen = 110;
memcpy(this->dataBuf, data, dataLen); //copy 110 bytes to dataBuf //but no error or warning from compiler, and no runtime error indicates the cross
}
bool BitState::parseData(BitLog* bitLog)//pass pointer of dataBuf to para_tmp, but only use 0x08 + 4 = 12 bytes of dataBuf
{
Para* para_tmp;
if(*(this->dataBuf) == 0x77)
{
para_tmp = (ERRORTLV*)this->dataBuf;
}
if(para_tmp->type != 0x72 || para_tmp->inType != 0x97 || (para_tmp->len - para_tmp->inLen) != 2) // inLen == 0x08
{
return false;
}
else
{
//parse dataBuf according to Para's structure
this->bitState.reset();
for(int i = 0; i < para_tmp->inLen; i++) // inLen == 0x08 only !!!
{
this->bitState[para_tmp->value[i]-6] = 1;
}
if(this->bitState.none())
this->setState(NORMAL);
else
this->setState(FAULT);
QString currentTime = (QDateTime::currentDateTime()).toString("yyyy.MM.dd hh:mm:ss.zzz");
string sysTime = string((const char *)currentTime.toLocal8Bit());
this->setCurTime(sysTime);
this->addLog(sysTime, bitLog);
}
return true;
}
bool BitState::addLog(std::string sysTime, BitLog* bitLog)// this function is right
{
bitLog->basicInfo = this->basicInfo;//not in data Buf, already allocated and initialized, (right)
bitLog->bitState = this->bitState; //state is set by setState(..)
bitLog->rcvTime = sysTime; //time
return true;
}
Generally speaking, the program allocates 96 bytes to a byte array, but use 'memcpy(...)' to copy 110 bytes to the array, later uses only 12 bytes of the array.
All kinds of crashes appear, which are confusing and frustrating...:( :( :(