CODEWITHSUNDEEP
c++multithreadingmultiple-instances
Flave
Flave

Reputation: 77

How to instantiate multiple threads using the same function C++

Here is function execute(), used for some instructions:

void execute() {

while (run) { //thread is running

    if (time % 3 == 0) { // execute instructions when clock is 3
        Instruct Instr;
        uint16_t src1 = 0;
        uint16_t src2 = 0;
        int target_cycle = time;
        while (target_cycle > time) {
            std::this_thread::sleep_for(thread_sleep);
        }

        while (hpp_DE_EX.size() != 0) {

            Instr = hpp_DE_EX.front();

            hpp_DE_EX.pop();

            uint16_t instr = Instr.header;

            ptrLog->PrintData(get, instr);

            src2 = instr & 0x1F;

            src1 = (instr >> 0x5) & 0x1F;

            uint16_t opcode = (instr >> 0xA) & 0x3F;   

            ....

      }


 //For running this thread:
 auto exThread = std::thread(&processor::execute, this);
 exThread.detach();

Using this function execute(), I want to create multiple instances of threads. I think this is a possibility to declare the threads (but when I am write this code I am getting some errors - INVOKE ERROR C2672) --- MODIFIED and now working

    std::vector<std::thread> threads;
    for (int i = 0; i <= 5; i++) // need 5 instances
    threads.push_back(thread(&processor::execute, this));

    cout << "Synchronizing all threads...\n";
    for (auto& th : threads) th.join();   // Running code

My intention is to use the execute() function (threads) to execute parallel instruction instead of linear instructions - functionable parameter.

Thanks, F.

Upvotes: 2

Views: 1072

Answers (1)

Alan Birtles
Alan Birtles

Reputation: 36488

Assuming processor::execute is a static member function with no arguments then you are passing an extra argument to it so the std::thread implementation can't find an overload with the correct arguments. The correct invocation is:

threads.push_back(thread(&processor::execute));

or more simply:

threads.emplace_back(&processor::execute);

If it isn't a static method then you need to pass an instance of your processor class, e.g.:

processor p;
for (int i = 0; i <= 5; i++)
{
    threads.emplace_back(&processor::execute, &p);
}

Judging by printing "Synchronizing all threads" I think you don't understand what std::thread::detach does, it detaches the thread from the std::thread instance so that it can continue running once the structure is destroyed. I assume you actually meant to call std::thread::join which waits for the thread to finish executing. std::thread::detach is rarely the correct thing to do.

Upvotes: 5

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