#include <iostream>
#include <queue>
#include <thread>
#include <process.h>
#include <windows.h>
#include <stdlib.h>
int g_Width = 100;
std::queue<std::vector<unsigned short>> BufferQueue;
bool dataRead = false;
unsigned short* g_pImgBuf = NULL;
unsigned int _stdcall Write(void* arg) {
std::vector<unsigned short> data;
data.reserve(g_Width);
int line = 0;
while (dataRead)
{
if (!dataRead)
break;
for (int i = 0; i < g_Width; i++) {
data.push_back(i);
}
BufferQueue.push(data);
data.clear();
}
_endthreadex(0);
return 0;
}
unsigned int _stdcall Read(void* arg) {
std::vector<unsigned short> data;
data.reserve(g_Width);
unsigned short color = 0;
int line = 0;
while (dataRead)
{
g_pImgBuf = new unsigned short[g_Width];
if (!BufferQueue.empty()) {
data = BufferQueue.front();
BufferQueue.pop();
}
else if (!dataRead)
break;
else {
continue;
}
for (int j = 0; j < g_Width; j++) {
color = data[j];
color += 2;
g_pImgBuf[j] = color;
}
data.clear();
}
if (g_pImgBuf) { free(g_pImgBuf); g_pImgBuf = NULL; }
_endthreadex(0);
return 0;
}
int main()
{
dataRead = true;
HANDLE r_hThread = NULL;
unsigned r_threadID;
r_hThread = (HANDLE)_beginthreadex(NULL, 0, Read, NULL, 0, &r_threadID);
HANDLE w_hThread = NULL;
unsigned w_threadID;
w_hThread = (HANDLE)_beginthreadex(NULL, 0, Write, NULL, 0, &w_threadID);
while (true)
{
Sleep(100);
}
}
The following error occurred
vector subscript out of range 1501 error
In the middle of the thread function
Give it sleep (2) and it works sometimes but soon I get an error.
If the vector is the problem, is there any other way to store the array in the queue?
I don't know where the problem is
Is there a good way?
You simply cannot do this in such a simplistic way. If you want one thread to pick messages off the queue that are being written by another thread you need mtuexes and condition variables. This is not a trivial task. I suggest a lot of googling. I will look too and updat here if I find a good link
https://juanchopanzacpp.wordpress.com/2013/02/26/concurrent-queue-c11/
https://gist.github.com/ictlyh/f8473ad0cb1008c6b32c41f3dea98ef5
Related
I use ftd3xx.dll to communicate with the device
The data read part and the data write part are divided into threads and used.
#include <thread>
#include <queue>
#include <array>
#include <windows.h>
using namespace std;
bool dataRead = false;
CRITICAL_SECTION sec;
queue< vector<unsigned short>> BufferQueue;
unsigned WINAPI Write(void* arg) {
int Width = 1000;
vector<unsigned short> data;
data.reserve(Width);
while (Opened)
{
while (dataRead)
{
if (BufferQueue.size() > 0) {
EnterCriticalSection(&sec);
data = BufferQueue.front();
BufferQueue.pop();
LeaveCriticalSection(&sec);
}
else
{
this_thread::sleep_for(2ms);
continue;
}
//wrtie something
}
if (!dataRead)
break;
}
_endthreadex(0);
return 0;
}
unsigned WINAPI Read(void* arg) {
int Width = 1000;
vector<unsigned short> data(Width);
BYTE* acReadBuf = new BYTE[Width];
ULONG ulBytesRead = 0;
int idx = 0;
Sleep(100);
while (dataRead)
{
ftStatus = FT_ReadPipe(ftHandle, CstReadPipeNo, acReadBuf, Width, &ulBytesRead, NULL);
if (FT_SUCCESS(ftStatus))
{
idx = 0;
for (int i = 0; i < Width; i++) {
data[i] = ((unsigned short)((unsigned short)acReadBuf[idx] | ((unsigned short)acReadBuf[idx + 1] << 8)));
idx += 2;
}
EnterCriticalSection(&sec);
if (BufferQueue.size() > 10000) {
queue< vector<unsigned short>> empty;
swap(BufferQueue, empty);
}
BufferQueue.push(data);
LeaveCriticalSection(&sec);
}
else
{
}
}
_endthreadex(0);
return 0;
}
void main() {
//start
InitializeCriticalSection(&sec);
dataRead = true;
HANDLE r_hThread = NULL;
unsigned r_threadID;
r_hThread = (HANDLE)_beginthreadex(NULL, 0, Read, NULL, 0, &r_threadID);
HANDLE w_hThread = NULL;
unsigned w_threadID;
w_hThread = (HANDLE)_beginthreadex(NULL, 0, Write, NULL, 0, &w_threadID);
//....///
//stop
dataRead = false;;
WaitForSingleObject(r_hThread, INFINITE);
WaitForSingleObject(w_hThread, INFINITE);
DeleteCriticalSection(&sec);
}
I want to queue the array directly, but first I am using it as a vector.
Importantly, data loss occurs when other programs are run or even calculators are run.
The same is true even if the device gives the data late or fast.
I would be grateful if someone could help me.
I'm new to pthread and attempting to implement a producer/consumer problem that will let the user pick buffer size, # of producers, # of consumers, and total # of items. I've been looking through what I thought were similar things on stack overflow, but can't seem to get it right.
My code has a main class and it spawns producers and consumers. It hands the producers and consumers a pointer to a stack initialized in main (or at least I'm trying to). I thought that what I was doing was legal and in CLion I get the predictive text options I want so I thought I linked it properly but I'm segfaulting when I try to read the top element.
I used GDB to make sure I knew what line I was crashing on, but don't understand what's wrong with my setup. While debugging I confirmed that a producer goes through its push() command first, but the consumer fails when attempting top() or pop(). I'd seen some threads here where the OP had problems because they didn't join their threads, but I am so I'm a little lost.
#include <iostream>
#include <stdlib.h>
#include <unistd.h>
#include <stdio.h>
#include <stack>
#include <cstring>
#include <semaphore.h>
#include <pthread.h>
#define N 10000
sem_t mutex;
sem_t fullCount;
sem_t emptyCount;
int iCount = 0;
typedef struct _thread_data{
int id;
int itemcount;
std::stack<char>* ptr;
}thread_data;
void *producer(void *arg){
std::cout << "spawned producer\n";
thread_data *data = (thread_data *)arg;
while(true){
char message = 'X';
sem_wait(&emptyCount);
sem_wait(&mutex);
if(iCount < data->itemcount){
data->ptr->push(message);
iCount++;
char temp [25];
sprintf(temp, "p:<%u>, item: %c, at %d\n", data->id, message, data->ptr->size());
std::cout << temp;
//std::cout << "hi I'm a producer\n";
sem_post(&mutex);
sem_post(&fullCount);
}
else{
sem_post(&fullCount);
sem_post(&mutex);
pthread_exit(nullptr);
}
}
}
void *consumer(void *arg){
std::cout << ("spawned consumer\n");
thread_data *data = (thread_data *)arg;
while(true){
char message;
sem_wait(&fullCount);
sem_wait(&mutex);
if(iCount < data->itemcount) {
message = data->ptr->top(); //SEGFAULT
char temp[25];
printf(temp, "c:<%u>, item: %c, at %d\n", data->id, message, data->ptr->size());
data->ptr->pop();
std::cout << temp;
//std::cout << "Hi I'm a consumer\n";
sem_post(&mutex);
sem_post(&emptyCount);
}
else if (iCount == data->itemcount){
message = data->ptr->top(); //SEGFAULT
char temp[25];
printf(temp, "c:<%u>, item: %c, at %d\n", data->id, message, data->ptr->size());
data->ptr->pop();
std::cout << temp;
sem_post(&emptyCount);
sem_post(&mutex);
pthread_exit(nullptr);
}
else{
sem_post(&mutex);
pthread_exit(nullptr);
}
}
}
int main(int argc, char *argv[]){
int bufferSize = N;
int pThreadCount,cThreadCount,itemCount;
for (int x = 0; x < argc; ++x) {
if(strcmp(argv[x],"-b") == 0){
bufferSize = atoi(argv[x+1]);
}
if(strcmp(argv[x],"-p") == 0){
pThreadCount = atoi(argv[x+1]);
}
if(strcmp(argv[x],"-c") == 0){
cThreadCount = atoi(argv[x+1]);
}
if(strcmp(argv[x],"-i") == 0){
itemCount = atoi(argv[x+1]);
}
}
sem_init(&mutex,1,1);
sem_init(&fullCount,1,0);
sem_init(&emptyCount,1,bufferSize);
std::stack<char> myStack;
pthread_t myPThreads[pThreadCount];
thread_data thrData[pThreadCount];
pthread_t myCThreads[cThreadCount];
thread_data cThrData[cThreadCount];
for (int i = 0; i < pThreadCount; ++i) {
thrData[i].id = i;
thrData[i].itemcount = itemCount;
thrData[i].ptr = &myStack;
pthread_create(&myPThreads[i], NULL, producer, &thrData[i]);
}
for (int i = 0; i < cThreadCount; ++i) {
cThrData[i].id = i;
cThrData[i].itemcount = itemCount;
thrData[i].ptr = &myStack;
pthread_create(&myCThreads[i], NULL, consumer, &cThrData[i]);
}
for (int k = 0; k < pThreadCount; ++k) {
pthread_join(myPThreads[k], NULL);
}
for (int j = 0; j < cThreadCount; ++j) {
pthread_join(myCThreads[j], NULL);
}
return 0;
}
iCount <= data->itemcount is always true. consumer never exits the loop. At some point, it exhausts the stack, and the subsequent top() call exhibits undefined behavior.
cThrData[i].ptr is never initialized, for any i. consumer calls top() through an uninitialized pointer, whereupon the program exhibits undefined behavior.
How do you copy one stream to another using dedicated read/write threads in C++?
Let's say I have these methods (not real, but to illustrate the point) to read/write data from. These read/write functions could represent anything (network/file/USB/serial/etc).
// returns the number of bytes read
void read(char* buffer, int bufferSize, int* bytesRead);
// returns the number of bytes written
void write(char* buffer, int bufferSize, int* bytesWritten);
The solution should also be portable.
NOTE: I am aware that Windows has a FILE_FLAG_OVERLAPPED feature, but this assumes that the read/write is file IO. Remember, these read/write methods could represent anything.
Here is the solution I came up with.
Header
#pragma once
#include <stdlib.h>
#include <queue>
#include <mutex>
#include <thread>
#include <chrono>
#include <list>
#include <thread>
#define ASYNC_COPY_READ_WRITE_SUCCESS 0
struct BufferBlock;
struct ReadStream
{
// read a stream to a buffer.
// return non-zero if error occured
virtual int read(char* buffer, int bufferSize, int* bytesRead) = 0;
};
struct WriteStream
{
// write a buffer to a stream.
// return non-zero if error occured
virtual int write(char* buffer, int bufferSize, int* bytesWritten) = 0;
};
class BufferBlockManager
{
public:
BufferBlockManager(int numberOfBlocks, int bufferSize);
~BufferBlockManager();
void enqueueBlockForRead(BufferBlock* block);
void dequeueBlockForRead(BufferBlock** block);
void enqueueBlockForWrite(BufferBlock* block);
void dequeueBlockForWrite(BufferBlock** block);
void resetState();
private:
std::list<BufferBlock*> blocks;
std::queue<BufferBlock*> blocksPendingRead;
std::queue<BufferBlock*> blocksPendingWrite;
std::mutex queueLock;
std::chrono::milliseconds dequeueSleepTime;
};
void AsyncCopyStream(BufferBlockManager* bufferBlockManager, ReadStream* readStream, WriteStream* writeStream, int* readResult, int* writeResult);
CPP
#include "AsyncReadWrite.h"
struct BufferBlock
{
BufferBlock(int bufferSize) : buffer(NULL)
{
this->bufferSize = bufferSize;
this->buffer = new char[bufferSize];
this->actualSize = 0;
this->isLastBlock = false;
}
~BufferBlock()
{
this->bufferSize = 0;
free(this->buffer);
this->buffer = NULL;
this->actualSize = 0;
}
char* buffer;
int bufferSize;
int actualSize;
bool isLastBlock;
};
BufferBlockManager::BufferBlockManager(int numberOfBlocks, int bufferSize)
{
dequeueSleepTime = std::chrono::milliseconds(100);
for (int x = 0; x < numberOfBlocks; x++)
{
BufferBlock* block = new BufferBlock(bufferSize);
blocks.push_front(block);
blocksPendingRead.push(block);
}
}
BufferBlockManager::~BufferBlockManager()
{
for (std::list<BufferBlock*>::const_iterator iterator = blocks.begin(), end = blocks.end(); iterator != end; ++iterator) {
delete (*iterator);
}
}
void BufferBlockManager::enqueueBlockForRead(BufferBlock* block)
{
queueLock.lock();
block->actualSize = 0;
block->isLastBlock = false;
blocksPendingRead.push(block);
queueLock.unlock();
}
void BufferBlockManager::dequeueBlockForRead(BufferBlock** block)
{
WAITFOR:
while (blocksPendingRead.size() == 0)
std::this_thread::sleep_for(dequeueSleepTime);
queueLock.lock();
if (blocksPendingRead.size() == 0)
{
queueLock.unlock();
goto WAITFOR;
}
*block = blocksPendingRead.front();
blocksPendingRead.pop();
queueLock.unlock();
}
void BufferBlockManager::enqueueBlockForWrite(BufferBlock* block)
{
queueLock.lock();
blocksPendingWrite.push(block);
queueLock.unlock();
}
void BufferBlockManager::dequeueBlockForWrite(BufferBlock** block)
{
WAITFOR:
while (blocksPendingWrite.size() == 0)
std::this_thread::sleep_for(dequeueSleepTime);
queueLock.lock();
if (blocksPendingWrite.size() == 0)
{
queueLock.unlock();
goto WAITFOR;
}
*block = blocksPendingWrite.front();
blocksPendingWrite.pop();
queueLock.unlock();
}
void BufferBlockManager::resetState()
{
queueLock.lock();
blocksPendingRead = std::queue<BufferBlock*>();
blocksPendingWrite = std::queue<BufferBlock*>();
for (std::list<BufferBlock*>::const_iterator iterator = blocks.begin(), end = blocks.end(); iterator != end; ++iterator) {
(*iterator)->actualSize = 0;
}
queueLock.unlock();
}
struct AsyncCopyContext
{
AsyncCopyContext(BufferBlockManager* bufferBlockManager, ReadStream* readStream, WriteStream* writeStream)
{
this->bufferBlockManager = bufferBlockManager;
this->readStream = readStream;
this->writeStream = writeStream;
this->readResult = ASYNC_COPY_READ_WRITE_SUCCESS;
this->writeResult = ASYNC_COPY_READ_WRITE_SUCCESS;
}
BufferBlockManager* bufferBlockManager;
ReadStream* readStream;
WriteStream* writeStream;
int readResult;
int writeResult;
};
void ReadStreamThread(AsyncCopyContext* asyncContext)
{
int bytesRead = 0;
BufferBlock* readBuffer = NULL;
int readResult = ASYNC_COPY_READ_WRITE_SUCCESS;
while (
// as long there hasn't been any write errors
asyncContext->writeResult == ASYNC_COPY_READ_WRITE_SUCCESS
// and we haven't had an error reading yet
&& readResult == ASYNC_COPY_READ_WRITE_SUCCESS)
{
// let's deque a block to read to!
asyncContext->bufferBlockManager->dequeueBlockForRead(&readBuffer);
readResult = asyncContext->readStream->read(readBuffer->buffer, readBuffer->bufferSize, &bytesRead);
readBuffer->actualSize = bytesRead;
readBuffer->isLastBlock = bytesRead == 0;
if (readResult == ASYNC_COPY_READ_WRITE_SUCCESS)
{
// this was a valid read, go ahead and queue it for writing
asyncContext->bufferBlockManager->enqueueBlockForWrite(readBuffer);
}
else
{
// an error occured reading
asyncContext->readResult = readResult;
// since an error occured, lets queue an block to write indicatiting we are done and there are no more bytes to read
readBuffer->isLastBlock = true;
readBuffer->actualSize = 0;
asyncContext->bufferBlockManager->enqueueBlockForWrite(readBuffer);
}
if (readBuffer->isLastBlock) return;
}
}
void WriteStreamThread(AsyncCopyContext* asyncContext)
{
int bytesWritten = 0;
BufferBlock* writeBuffer = NULL;
int writeResult = ASYNC_COPY_READ_WRITE_SUCCESS;
bool isLastWriteBlock = false;
while (
// as long as there are no errors during reading
asyncContext->readResult == ASYNC_COPY_READ_WRITE_SUCCESS
// and we haven't had an error writing yet
&& writeResult == ASYNC_COPY_READ_WRITE_SUCCESS)
{
// lets dequeue a block for writing!
asyncContext->bufferBlockManager->dequeueBlockForWrite(&writeBuffer);
isLastWriteBlock = writeBuffer->isLastBlock;
if (writeBuffer->actualSize > 0)
writeResult = asyncContext->writeStream->write(writeBuffer->buffer, writeBuffer->actualSize, &bytesWritten);
if (writeResult == ASYNC_COPY_READ_WRITE_SUCCESS)
{
asyncContext->bufferBlockManager->enqueueBlockForRead(writeBuffer);
if (isLastWriteBlock) return;
}
else
{
asyncContext->writeResult = writeResult;
asyncContext->bufferBlockManager->enqueueBlockForRead(writeBuffer);
return;
}
}
}
void AsyncCopyStream(BufferBlockManager* bufferBlockManager, ReadStream* readStream, WriteStream* writeStream, int* readResult, int* writeResult)
{
AsyncCopyContext asyncContext(bufferBlockManager, readStream, writeStream);
std::thread readThread(ReadStreamThread, &asyncContext);
std::thread writeThread(WriteStreamThread, &asyncContext);
readThread.join();
writeThread.join();
*readResult = asyncContext.readResult;
*writeResult = asyncContext.writeResult;
}
Usage
#include <stdio.h>
#include <tchar.h>
#include "AsyncReadWrite.h"
struct ReadTestStream : ReadStream
{
int readCount = 0;
int read(char* buffer, int bufferSize, int* bytesRead)
{
printf("Starting read...\n");
memset(buffer, bufferSize, 0);
if (readCount == 10)
{
*bytesRead = 0;
return 0;
}
// pretend this function takes a while!
std::this_thread::sleep_for(std::chrono::milliseconds(100));
char buff[100];
sprintf_s(buff, "This is read number %d\n", readCount);
strcpy_s(buffer, sizeof(buff), buff);
*bytesRead = strlen(buffer);
readCount++;
printf("Finished read...\n");
return 0;
}
};
struct WriteTestStream : WriteStream
{
int write(char* buffer, int bufferSize, int* bytesWritten)
{
printf("Starting write...\n");
// pretend this function takes a while!
std::this_thread::sleep_for(std::chrono::milliseconds(500));
printf(buffer);
printf("Finished write...\n");
return 0;
}
};
int _tmain(int argc, _TCHAR* argv[])
{
BufferBlockManager bufferBlockManager(5, 4096);
ReadTestStream readStream;
WriteTestStream writeStream;
int readResult = 0;
int writeResult = 0;
printf("Starting copy...\n");
AsyncCopyStream(&bufferBlockManager, &readStream, &writeStream, &readResult, &writeResult);
printf("Finished copy... readResult=%d writeResult=%d \n", readResult, writeResult);
getchar();
return 0;
}
EDIT: I put my solution into a GitHub repository here. If you wish to use this code, refer to the repository since it may be more updated than this answer.
Typically, you would just have one thread for each direction that alternates between reads and writes.
#include <stdio.h>
#include <process.h>
#include <wtypes.h>
typedef unsigned int (__stdcall * THREAD_FUN_TYPE)(void *);
int ThreadIp(void* param)
{
while(true)
{
printf("I'm runing!\n");
}
return 0;
}
int main()
{
int iThreadNum=100;
HANDLE* phThreads = new HANDLE[iThreadNum];
for (int i=0;i<iThreadNum;++i)
{
phThreads[i]=(HANDLE*)_beginthreadex(NULL, 0, (THREAD_FUN_TYPE)ThreadIp,NULL, NULL, NULL);
}
int nIndex = ::WaitForMultipleObjects(iThreadNum,phThreads,1,INFINITE);
printf("End!\n");
return 0;
}
I want the program will halt at WaitForMultipleObjects until all thread are end(Not until all thread are created successfully).But the program will not halt at WaitForMultipleObjects,while all threads are still running. So I try to use SetEvent,but still the same problem:
int iThreadNum=100;
HANDLE* phThreads = new HANDLE[iThreadNum];
for (int i=0;i<iThreadNum;++i)
{
phThreads[i]=CreateEvent(NULL, FALSE, FALSE,NULL);
ResetEvent(phThreads[i]);
}
int nIndex = ::WaitForMultipleObjects(iThreadNum,phThreads,1,INFINITE);
You should wait on the thread handles, not the unrelated events:
Try something like this:
int iThreadNum=100;
HANDLE* phThreads = new HANDLE[iThreadNum];
for (int i=0;i<iThreadNum;++i)
{
m_iCurThreadNum=i;
phThreads[i] = _beginthreadex(...);
}
int nIndex = ::WaitForMultipleObjects(iThreadNum,phThreads,1,INFINITE);
Does it work if you have fewer threads? The manual says you need to do extra work if you have more than MAXIMUM_WAIT_OBJECTS, specifically
nCount [in] The number of object handles in the array pointed to by
lpHandles. The maximum number of object handles is
MAXIMUM_WAIT_OBJECTS. This parameter cannot be zero.
See here for a discussion.
It might be worth checking what the wait function has returned too.
I would allocate a struct before calling _beginthreadex and pass the pointer to the struct through the threads parameter and have the struct contain a bool which is set by the thread when it's done.
struct ThreadStruct{
bool Done;
char* ParamData;
int ParamDataSize;
};
int ThreadIp(void* param)
{
ThreadStruct* ts = (ThreadStruct*)param;
while(true)
{
printf("I'm runing!\n");
}
ts->Done = true;
return 0;
}
int main()
{
int iThreadNum=100;
HANDLE* phThreads = new HANDLE[iThreadNum];
ThreadStruct* structs = new ThreadStruct[iThreadNum];
for (int i=0;i<iThreadNum;++i)
{
ZeroMemory(structs[i], sizeof(ThreadStruct));
phThreads[i]=(HANDLE*)_beginthreadex(NULL, 0, (THREAD_FUN_TYPE)ThreadIp, structs[i], NULL, NULL);
ResetEvent(phThreads[i]);
}
for(unsigned int i=0; i<iThreadNum;){
if(!structs[i]->Done) i=0;
else i++;
}
printf("End!\n");
return 0;
}
// windows_procon.cpp : Defines the entry point for the console application.
#include "stdafx.h"
#include <stdlib.h>
#include <iostream>
#include <time.h>
#include <windows.h>
#include <process.h>
using namespace std;
HANDLE mutex;
HANDLE emptySlots;
HANDLE filledSlots;
#define BUFFER_SIZE 10
void *producer(void *);
void *consumer(void *);
int produceItem(void);
void printBuffer(void);
int buffer[BUFFER_SIZE];
int head = 0;
int tail = 0;
int _tmain(int argc, _TCHAR* argv[])
{
DWORD prodThrdID, consThrdID;
mutex = CreateMutex(NULL,FALSE,NULL);
emptySlots = CreateSemaphore(NULL,BUFFER_SIZE,BUFFER_SIZE,NULL);
filledSlots = CreateSemaphore(NULL,0,0,NULL);
srand(time(NULL));
_beginthreadex(NULL, 0, (unsigned int(__stdcall *)(void*))producer,
0, 0, (unsigned int *)&prodThrdID);
_beginthreadex(NULL, 0, (unsigned int(__stdcall *)(void*))consumer,
0, 0, (unsigned int *)&consThrdID);
return 0;
}
void *producer(void *n)
{
int item;
for(int i = 0; i <BUFFER_SIZE+5; i++)
{
WaitForSingleObject(emptySlots,INFINITE);
WaitForSingleObject(mutex,INFINITE);
item = produceItem();
//printf("Producing");
cout << "Producing: " << item << endl;
//logfile << "Producing: "<< item << endl;
//fprintf(logfile, "Producing: %d \n", item);
buffer[head] = item;
head = (head + 1) % BUFFER_SIZE;
printBuffer();
ReleaseMutex(mutex);
ReleaseSemaphore(filledSlots,1, NULL);
}
return n;
}
void *consumer(void *n)
{
for(int i = 0; i <BUFFER_SIZE+5; i++)
{
WaitForSingleObject(filledSlots,INFINITE);
//Sleep(500);
WaitForSingleObject(mutex,INFINITE);
cout << "Consuming: " << buffer[tail] << endl;
buffer[tail] = 0;
tail = (tail + 1) % BUFFER_SIZE;
printBuffer();
ReleaseMutex(mutex);
ReleaseSemaphore(emptySlots,1, NULL);
}
return n;
}
int produceItem(void)
{
int x = (rand()%11 + 1);
return x;
}
void printBuffer(void)
{
for(int i = 0; i <BUFFER_SIZE; i++)
{
printf("%d ", buffer[i]);
}
printf("END \n");
}
My program here is supposed to be an algorithm for the producer-consumer problem. I think I have the algorithm correct my only problem is that I'm having trouble getting the threads to run properly. Can someone tell me what the issue is?
You need to wait for the threads you create with _beginthreadex to do their work, as it stands you program will exit immediately after creating them. I haven't looked any further at you logic.
Here is an example.
hThread = (HANDLE)_beginthreadex( NULL, 0, &SecondThreadFunc, NULL, 0, &threadID );
WaitForSingleObject( hThread, INFINITE );