C++11 Thread not working

Question

My programs looks like below

#include <iostream>
#include <thread>
#include <exception>

void hello()
{
    std::cout << "Hello world!!!!" << std::endl;
}

int main()
{
    std::cout << "In Main\n";
    std::thread t(hello);
    t.join();
    return 0;
}

When I compile it using the following command I get no errors

g++-4.7 -std=c++11 main.cpp

But when I run it I get the following error

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

Could someone help me with where I am going wrong?

it most probably won't be the root cause of the error message you see, but std::cout (and others) are not supposed to be used concurrently without access serialization — bobah, Nov 05 '12 at 07:15
@bobah - there's no concurrent use here. The insertion in `main()` finished before the thread is created. — Pete Becker, Nov 05 '12 at 13:11
@PeteBecker - that's precisely why I said "most probably won't be" — bobah, Nov 05 '12 at 14:02

score 10 · Accepted Answer · edited May 20 '14 at 17:26

10

When I use C++11 threads with GCC, i use:

g++ -std=c++0x -pthread -g main.cpp

That works for me.

edited May 20 '14 at 17:26

Dan

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answered Nov 05 '12 at 07:14

Michael McGuire

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But why do we have to include -pthread when is available in the std library??? – Alwin Doss Nov 05 '12 at 07:17
GCC doesn't automatically include the pthread library yet. They said it will be fixed in a later version. – Michael McGuire Nov 05 '12 at 07:19
would you have a link to where they have mentioned that. Would like to read that article – Alwin Doss Nov 05 '12 at 07:20
I can't remember where I read that. So, I guess I failed the Citation Needed test. – Michael McGuire Nov 05 '12 at 07:26

score 6 · Answer 2 · edited May 23 '17 at 12:06

6

When compiling your code with g++, use the -pthread option.

Below is the answer I find from stackoverflow: In g++ is C++ 11 thread model using pthreads in the background?

edited May 23 '17 at 12:06

Community

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answered Nov 05 '12 at 07:14

billz

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score 3 · Answer 3 · answered Nov 06 '12 at 23:53

Everybody already answered that you need the -pthread argument passed to the compiler. Almost for sure it won't change in 4.8 but according to http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52681 the exception will at least have a nice message stating what's wrong.

score 0 · Answer 4 · answered Nov 05 '12 at 07:10

0

You might need to link against the pthread library

answered Nov 05 '12 at 07:10

gvd

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score 0 · Answer 5 · edited Jun 02 '15 at 13:27

0

You can try with,

g++ --std=c++11 -lpthread main.cpp

edited Jun 02 '15 at 13:27

Andy

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answered Jun 02 '15 at 13:21

thispointer.com

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Please elaborate. What's the difference and why does it provide a solution? – TobiMcNamobi Jun 02 '15 at 14:07

C++11 Thread not working

5 Answers5

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