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#include "FWCore/Concurrency/interface/ThreadSafeOutputFileStream.h"
#include <atomic>
#include <sstream>
#include <thread>
#include <vector>
namespace {
std::atomic<int> nWaitingForThreads{};
void logToFile(unsigned const thread_index, edm::ThreadSafeOutputFileStream& f) {
--nWaitingForThreads;
while (nWaitingForThreads != 0)
; // Spin until all threads have been launched.
std::ostringstream oss;
oss << "Thread index: " << thread_index << " Entry: ";
auto const& prefix = oss.str();
for (int i{}; i < 4; ++i) {
f.write(prefix + std::to_string(i) + "\n");
}
}
} // namespace
int main() {
edm::ThreadSafeOutputFileStream f{"thread_safe_ofstream_test.txt"};
std::vector<std::thread> threads;
unsigned const nThreads{3};
nWaitingForThreads = nThreads;
for (unsigned i{}; i < nThreads; ++i) {
threads.emplace_back(logToFile, i, std::ref(f));
}
for (auto& thread : threads)
thread.join();
}
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