Question

很抱歉我还有这个问题。

我试图运行以下代码：

int main() {
//called_from_async launched in a separate thread if possible
std::future<int> result(
        std::async([](int m, int n) {return m + n;}, 2,
                4));

std::cout << "Message from main." << std::endl;

//retrive and print the value stored in the future
std::cout << result.get() << std::endl;

return 0;
}

运行它我看到以下输出：

Message from main.
terminate called after throwing an instance of 'std::system_error'
  what():  Unknown error -1
Aborted (core dumped)

在＆＃39; std :: async＆＃39;中做了一些小改动。拨打：

int main() {
//called_from_async launched in a separate thread if possible
std::future<int> result(
        std::async(std::launch::async, [](int m, int n) {return m + n;}, 2,
                4));

std::cout << "Message from main." << std::endl;

//retrive and print the value stored in the future
std::cout << result.get() << std::endl;

return 0;
}

我看到以下内容：

terminate called after throwing an instance of 'std::system_error'
  what():  Enable multithreading to use std::thread: Operation not permitted
Aborted (core dumped)

我使用以下命令：

 g++  ASYNC_CPP11.cpp -o ASYNC -pthread -std=c++11

＆＃39; gcc -v＆＃39;命令发出以下内容：

Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/4.8/lto-wrapper
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu/Linaro 4.8.1-10ubuntu9' --with-bugurl=file:///usr/share/doc/gcc-4.8/README.Bugs --enable-languages=c,c++,java,go,d,fortran,objc,obj-c++ --prefix=/usr --program-suffix=-4.8 --enable-shared --enable-linker-build-id --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --with-gxx-include-dir=/usr/include/c++/4.8 --libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --enable-gnu-unique-object --enable-plugin --with-system-zlib --disable-browser-plugin --enable-java-awt=gtk --enable-gtk-cairo --with-java-home=/usr/lib/jvm/java-1.5.0-gcj-4.8-amd64/jre --enable-java-home --with-jvm-root-dir=/usr/lib/jvm/java-1.5.0-gcj-4.8-amd64 --with-jvm-jar-dir=/usr/lib/jvm-exports/java-1.5.0-gcj-4.8-amd64 --with-arch-directory=amd64 --with-ecj-jar=/usr/share/java/eclipse-ecj.jar --enable-objc-gc --enable-multiarch --disable-werror --with-arch-32=i686 --with-abi=m64 --with-multilib-list=m32,m64,mx32 --with-tune=generic --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu
Thread model: posix
gcc version 4.8.1 (Ubuntu/Linaro 4.8.1-10ubuntu9)

我缺少什么选项？

再次，抱歉复制问题。谢谢。

std :: async throws＆＃39; std :: system_error＆＃39;在自定义GCC 4.8.1中

0 个答案: