lldb/test/API/commands/process/attach-resume/main.cpp

#include "attach.h"
#include <chrono>
#include <cstdio>
#include <fcntl.h>
#include <thread>

volatile bool debugger_flag = true; // The debugger will flip this to false

void *start(void *data)
{
    int i;
    size_t idx = (size_t)data;
    for (i=0; i<30; i++)
    {
        if ( idx == 0 && debugger_flag)
            std::this_thread::sleep_for(std::chrono::microseconds(1)); // Set breakpoint here
        std::this_thread::sleep_for(std::chrono::seconds(1));
    }
    return 0;
}

int main(int argc, char const *argv[])
{
    lldb_enable_attach();

    static const size_t nthreads = 16;
    std::thread threads[nthreads];
    size_t i;

    for (i=0; i<nthreads; i++)
        threads[i] = std::move(std::thread(start, (void*)i));

    for (i=0; i<nthreads; i++)
        threads[i].join();
}