编译器:g++ 9.2.0 操作系统。Windows 10 g++调用。
g++ -E main.cpp -v -o main.i
g++ -c main.cpp -v -o main.o
g++ main.o -v -o main.exe
main.exe
main.cpp:
#include <chrono>
#include <iostream>
#include <string>
#include <exception>
#include <iostream>
//#include <thread>
#include "mingw.thread.h"
struct Object{
struct Exception : public std::exception{
std::string error_;
Exception(std::string str){
this->error_ = str;
}
~Exception() {
}
std::string get(){
return error_;
}
};
void DoSomeWork() {
try {
std::thread AnotherTh(&Object::GenerateException ,this);
AnotherTh.detach ();
while(true);
}
catch (...) {
throw ;
}
}
void GenerateException(){
std::this_thread::sleep_for (std::chrono::seconds(5));
throw Object::Exception ("Some error");
}
};
int main(){
try{
Object instance;
std::thread th(&Object::DoSomeWork,std::ref(instance));
th.join ();
}
catch (Object::Exception &ex ) {
std::cout << ex.get ();
}
catch (std::exception &ex ){
std::cout << ex.what ();
}
catch (...){
}
std::cout << "never reach this";
return 0;
}
输出:我正在启动
terminate called after throwing an instance of 'Object::Exception'
what(): std::exception
我正在启动 主线 附带 新线 等着吧,在里面 钍 开始 另一线 异常将被抛出的地方。所以,当它出现时,开始堆栈解开(从Object::GenerateException到Object::DoSomeWork,因为Object::GenerateException的堆栈中没有更多的调用),并将管理传递给Object::DoSomeWork的try-catch,有相同的调用链到main的try-catch,因为Object::DoSomeWork "知道 "它是从main被调用的。
我不明白为什么它不能处理异常并将其传递给main的try-catch。
为什么c++程序在堆栈拆线后不能达到正确的返回指令?
因为你的代码创建了多个线程,而你没有在实际抛出异常的线程中捕获异常。异常不会在线程间传播,即使你调用了 join()
成员函数 std::thread
.
尝试块 被定义为堆栈的动态结构。try块从它的内容中捕捉动态地、通过调用达到的代码所抛出的异常。
当你创建一个新的线程时,你创建了一个全新的堆栈,这个堆栈根本不属于 try 块的动态上下文,即使调用了 pthread_create
或构建可连接 std::thread()
是在try里面。
要捕获源自线程X的异常,必须在线程X中设置try-catch子句(例如,在线程函数中的所有内容周围,类似于在main中的做法)。
相关的问题,请看 如何在线程之间传播异常?.
一个例子。
#include <chrono>
#include <iostream>
#include <string>
#include <exception>
#include <iostream>
#include <thread>
struct Object {
void DoSomeWork()
{
std::cout << "DoSomeWork Thread ID: " << std::this_thread::get_id() << std::endl;
try {
std::thread thread(&Object::GenerateException, this);
thread.detach();
while(true);
}
catch (...) {
std::cout << "Caught exception: " << std::this_thread::get_id() << std::endl;
throw ;
}
}
void GenerateException(void)
{
std::cout << "GenerateException Thread ID: " << std::this_thread::get_id() << std::endl;
try {
std::this_thread::sleep_for (std::chrono::seconds(5));
throw std::runtime_error("Some error");
} catch (...) {
std::cout << "Caught exception: " << std::this_thread::get_id() << std::endl;
throw;
}
}
};
int main()
{
std::cout << "Main Thread ID: " << std::this_thread::get_id() << std::endl;
try {
Object instance;
std::thread th(&Object::DoSomeWork,std::ref(instance));
th.join();
}
catch (const std::exception &ex) {
std::cout << ex.what() << std::endl;
std::cout << "Exception caught at: " << std::this_thread::get_id() << std::endl;
}
std::cout << "never reach this" << std::endl;
return 0;
}
输出:
Main Thread ID: 140596684195648
DoSomeWork Thread ID: 140596665124608
GenerateException Thread ID: 140596656670464
Caught exception: 140596656670464
terminate called after throwing an instance of 'std::runtime_error'
what(): Some error
Aborted (core dumped)