What are the correct link options to use std::thread in GCC under linux?

90
votes

Hi I am trying to use std::thread with G++. Here is my test code

#include <thread>
#include <iostream>

int main(int, char **){
    std::thread tt([](){ std::cout<<"Thread!"<<std::endl; });
    tt.join();
}

It compiles, but when I try to run it the result is:

terminate called after throwing an instance of 'std::system_error'
  what():  Operation not permitted 
Aborted

My compiler version:

$ g++ --version
g++ (Ubuntu/Linaro 4.6.1-9ubuntu3) 4.6.1
Copyright (C) 2011 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

What is wrong with my test code?

UPDATE: I use the following command line to compile and run my code.

$ g++ -std=c++0x test.cpp
$ ./a.out

and I tried

$ g++ -std=c++0x -lpthread test.cpp
$ ./a.out

still the same.

5
c++multithreadingg++c++11
@Earth Engine: this SO answer explains why there are no link errors without the pthread library: stackoverflow.com/a/6266345/12711 Short answer: glibc has do-nothing stubs for many pthread functions. - Michael Burr
@EarthEngine can you please put the solution in an answer? Specifically that the -lpthread must follow the source file. - River

5 Answers

105
votes

I think on Linux pthread is used to implement std::thread so you need to specify the -pthread compiler option.

As this is a linking option, this compiler option need to be AFTER the source files:

$ g++ -std=c++0x test.cpp -pthread
6
votes

In addition to using -std=c++0x and -pthread you must not use -static.

5
votes

-std=c++11 -static -pthread -Wl,--whole-archive -lpthread -Wl,--no-whole-archive works together with -static!!!

See here: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=52590#c4

2
votes

Here's a simple CMake file for compiling a C++11 program that uses threads:

CMakeLists.txt:

cmake_minimum_required(VERSION 2.8)
list(APPEND CMAKE_CXX_FLAGS "-pthread -std=c++11 ${CMAKE_CXX_FLAGS}")
add_executable(main main.cpp)

One way of building it is:

mkdir -p build
cd build
cmake .. && make
1
votes

Try compiling this way in single command:

g++ your_prog.cpp -o your_output_binary -lpthread -std=gnu++11

You can also try C++11 instead of gnu++11. Hope this works.