On Tue, Oct 31, 2017 at 7:15 AM, Bob Wilkinson <bob.wilkinson@xxxxxxxxxxx> wrote: > On Mon, Oct 30, 2017 at 10:22:03AM -0400, Brian Groose wrote: >> Hi Bob, >> >> Yes, I have -pthread, in fact, it won't even compile (much less try to >> link) because the declaration isn't visible without -pthread. >> I verified that the linker is looking at the pthread version of libstdc++.a >> as well, which shows the type "L" AIX TLS symbols when I run nm on it. >> >> I've tried compiling gcc without and without --enable-tls, which doesn't >> seem to make any difference. > > Hello Brian > > I have never used call_once ... so I found a demo program at http://www.cplusplus.com/reference/mutex/call_once/ > and compiled it. Results below. > > bash-4.4$ cat > call_once_2.cpp > // call_once example > #include <iostream> // std::cout > #include <thread> // std::thread, std::this_thread::sleep_for > #include <chrono> // std::chrono::milliseconds > #include <mutex> // std::call_once, std::once_flag > > int winner; > void set_winner (int x) { winner = x; } > std::once_flag winner_flag; > > void wait_1000ms (int id) { > // count to 1000, waiting 1ms between increments: > for (int i=0; i<1000; ++i) > std::this_thread::sleep_for(std::chrono::milliseconds(1)); > // claim to be the winner (only the first such call is executed): > std::call_once (winner_flag,set_winner,id); > } > > int main () > { > std::thread threads[10]; > // spawn 10 threads: > for (int i=0; i<10; ++i) > threads[i] = std::thread(wait_1000ms,i+1); > > std::cout << "waiting for the first among 10 threads to count 1000 ms...\n"; > > for (auto& th : threads) th.join(); > std::cout << "winner thread: " << winner << '\n'; > > return 0; > } > bash-4.4$ g++ -o call_once_2 -pthread call_once_2.cpp -lpthread > bash-4.4$ ./call_once_2 > waiting for the first among 10 threads to count 1000 ms... > winner thread: 2 > bash-4.4$ oslevel > 6.1.0.0 > bash-4.4$ uname -a > AIX bobaixgcc62 1 6 00FA21314C00 > bash-4.4$ > > So, that compilation works for me. I am using AIX6.1 as opposed to > your AIX 5.3. Please can you try compiling this small program on > your system, so that we can establish whether it is an AIX version > issue. Or maybe my compilation line will work for you? Maybe worth mentioning... std::call_once is c++11. I don't recall what GCC 4.8 uses by default, but -std=gnu11 or -std=c++11 may be useful. Older GCC's, like 4.4 and 4.7, are likely using gnu++03 by default (and may lack gnu++11 or c++11 support). Jeff
