Compiling multithread code with g++
Solution 1
The answer was provided by a kind member of SO C++ chat.
It looks like this behaviour is caused by a bug in gcc.
The workaround provided in the last comment of that bug discussion does work and solves the issue:
-Wl,--no-as-needed
Solution 2
Adding -lpthread
fixed the identical problem for me:
g++ -std=c++11 foo.cpp -lpthread -o foo
Solution 3
I have slightly more advanced version (4.8.4 instead of 4.8.1), and I tested all three answers above. In fact:
-pthread
alone works:
g++ -std=c++11 -o main -pthread main.cpp
-Wl,--no-as-needed
alone does not work.
-lpthread
alone does not work.
-Wl,--no-as-needed
and -lpthread
together work:
g++ -std=c++11 -o main -Wl,--no-as-needed main.cpp -lpthread
My version is "g++ (Ubuntu 4.8.4-2ubuntu1~14.04.1) 4.8.4".
Solution 4
answer already was made for qtcreator:
LIBS += -pthread
QMAKE_CXXFLAGS += -pthread
QMAKE_CXXFLAGS += -std=c++11
for console g++: here
g++ -c main.cpp -pthread -std=c++11 // generate target object file
g++ main.o -o main.out -pthread -std=c++11 // link to target binary
zerkms
Yet another software developer https://cv.zerkms.com/ #SOreadytohelp
Updated on September 21, 2020Comments
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zerkms almost 4 years
I have the easiest code ever:
#include <iostream> #include <thread> void worker() { std::cout << "another thread"; } int main() { std::thread t(worker); std::cout << "main thread" << std::endl; t.join(); return 0; }
though I still cannot compile it with
g++
to run.More details:
$ g++ --version g++ (Ubuntu/Linaro 4.8.1-10ubuntu8) 4.8.1 Copyright (C) 2013 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.
Command to compile:
$ g++ main.cpp -o main.out -pthread -std=c++11
Running:
$ ./main.out terminate called after throwing an instance of 'std::system_error' what(): Enable multithreading to use std::thread: Operation not permitted Aborted (core dumped)
And now I'm in stuck. In every related thread over the internet it's recommended to add
-pthread
while I have it already.What am I doing wrong?
PS: It's a brand new ubuntu 13.10 installation. Only
g++
package was installed and minor things likechromium
etcPPS:
$ ldd ./a.out linux-vdso.so.1 => (0x00007fff29fc1000) libstdc++.so.6 => /usr/lib/x86_64-linux-gnu/libstdc++.so.6 (0x00007fb85397d000) libgcc_s.so.1 => /lib/x86_64-linux-gnu/libgcc_s.so.1 (0x00007fb853767000) libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007fb85339e000) libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007fb85309a000) /lib64/ld-linux-x86-64.so.2 (0x00007fb853c96000)
PPPS: with
clang++
(v3.2) it compiles and runs finePPPPS: guys, it's not a duplicate of What is the correct link options to use std::thread in GCC under linux?
PPPPPS:
$ dpkg --get-selections | grep 'libc.*dev' libc-dev-bin install libc6-dev:amd64 install libclang-common-dev install linux-libc-dev:amd64 install
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scorpiodawg about 10 yearsWhat would I do without SO and guys like you? You saved me a headful of hair pulling. Thanks :) This is as obscure as it gets (for me at least)
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zerkms about 10 years@scorpiodawg: your comment made my evening, thanks :-)
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denim over 9 yearsThank you, your answer is the only one that makes it clear that the -pthread has to be passed to the compiler and the linker.
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thesaint over 9 yearsJep, this is the anwser and also completely reasonable. "-Wl,--no-as-needed" sounded weird and also doesn't work for me.
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The Paramagnetic Croissant over 8 yearsI had to add all of the
-pthread -lpthread -Wl,--no-as-needed
flags in order to get this work. -
cdunn2001 over 8 yearsYou definitely need
-lpthread
. You might need-pthread -Wl,--no-as-needed
, depending on compiler version. gcc-4.8.2 needs it. -
zerkms about 8 yearsWell, the solutions were provided for the different version and I can assure the checked answer did work at the moment I checked it. Anyway, thanks for the actual info.