https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97949
Bug ID: 97949
Summary: Recursive calls of std::call_once together with cout
leads to deadlock under mingw64
Product: gcc
Version: 10.1.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: libstdc++
Assignee: unassigned at gcc dot gnu.org
Reporter: fiesh at zefix dot tv
Target Milestone: ---
Host: x86_64-pc-linux-gnu
Target: x86_64-w64-mingw32.static
The following code locks under Windows 10:
-----------------------------
#include <chrono>
#include <iostream>
#include <mutex>
#include <thread>
std::once_flag flag0;
std::once_flag flag1;
void innerDoOnce()
{
std::call_once(flag0, []() {
using namespace std::chrono_literals;
std::cout << "innerDoOnce() called...\n";
std::this_thread::sleep_for(1s);
});
}
void outerDoOnce()
{
std::call_once(flag1, []() {
std::cout << "outerDoOnce() called...\n";
innerDoOnce();
});
}
int main()
{
std::thread t0(innerDoOnce);
std::thread t1(innerDoOnce);
std::thread t2(outerDoOnce);
std::thread t3(outerDoOnce);
t0.join();
t1.join();
t2.join();
t3.join();
std::cout << "aggi\n";
}
---------------------
Removing the `std::cout` calls seems to make the issue go away.
