使用boost :: asio :: spawn生成的asio处理程序中的boost :: property_tree :: read_xml segfaults [英] boost::property_tree::read_xml segfaults in an asio handler spawned using boost::asio::spawn

问题描述

以下代码在boost :: property_tree :: read_xml（）调用时因段错误而崩溃。
仅当在使用boost :: asio :: spawn（）产生的io_service处理程序内部调用时才会发生这种情况。如果该处理程序刚刚发布，则工作正常。
是否有解决方法或解决方法？
（提升1.61）

The following code crashes with a seg fault at boost::property_tree::read_xml() call. This happens only if it's called inside of an io_service handler spawned using boost::asio::spawn(). If the handler is just posted, it works ok. Is there a fix or workaround for this? (boost 1.61)

#include <boost/asio/spawn.hpp>
#include <boost/property_tree/ptree.hpp>
#include <boost/property_tree/xml_parser.hpp>
#include <iostream>
#include <sstream>
#include <thread>

void process()
{
    std::cerr << "start"<< std::endl;
    std::istringstream is("<t>1</t>");
    boost::property_tree::ptree pt;
    boost::property_tree::read_xml(is, pt); // <<< seg fault here
    std::cerr << std::endl << "end" << std::endl;
}

int main()
{
    boost::asio::io_service io_service;
    boost::asio::spawn(io_service, [] (boost::asio::yield_context y){
        process();
    });
    io_service.run();
    return 0;
}

推荐答案

经过一番挖掘，我们发现seg错误是由协程的堆栈溢出引起的，因为默认情况下，boost :: property_tree :: read_xml（）中使用的Rapidxml解析器会在堆栈中为每个xml文档中的静态内存池分配64KB。

After some digging we found that the seg fault is caused by coroutine's stack overflow because rapidxml parser used in boost::property_tree::read_xml() by default allocates 64KB on stack for the static memory pool within each xml document.

解决方案是按如下方式减小池的大小：

The solution is to reduce the size of the pool as follows:

#define BOOST_PROPERTY_TREE_RAPIDXML_STATIC_POOL_SIZE 512
#include <boost/property_tree/xml_parser.hpp>

另一种解决方案是增加协程的堆栈大小。

Another solution would be to increase the stack size of coroutines.

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