我已经编写了一个测试来显示asio async_accept的问题 我有一台服务器,可以永久打开任何连接 在接受了许多连接(在我的情况下是1017)之后 连接失败,出现“打开文件太多”错误。 然后对async_accept的任何调用立即调用处理程序
这是误会吗?
我使用debian 7 amd64
生成文件
CXX=clang++ -O2
OBJ= main.o server.o
LIBS=-lboost_system -lboost_thread
all: server
server: $(OBJ)
$(CXX) -o server $(OBJ) $(LIBS)
main.o: main.cpp
$(CXX) -c main.cpp
server.o: server.hpp server.cpp
$(CXX) -c server.cpp
clean:
rm -f *.o *~
distclean: clean
rm -f server
server.hpp
#include <boost/asio.hpp>
class server
{
public:
server();
void run();
private:
void start_accept();
void handle_accept(const boost::system::error_code& e);
boost::asio::io_service ios;
boost::asio::ip::tcp::acceptor acceptor_;
std::vector<boost::asio::ip::tcp::socket*> sockets;
};
server.cpp
#include <boost/bind.hpp>
#include "server.hpp"
server::server(): acceptor_(ios)
{
boost::asio::ip::tcp::resolver resolver(ios);
boost::asio::ip::tcp::resolver::query query("0.0.0.0", "5050");
boost::asio::ip::tcp::endpoint endpoint = *resolver.resolve(query);
acceptor_.open(endpoint.protocol());
acceptor_.set_option(boost::asio::ip::tcp::acceptor::reuse_address(true));
acceptor_.bind(endpoint);
acceptor_.listen();
start_accept();
}
void server::run()
{
ios.run();
}
void server::start_accept()
{
boost::asio::ip::tcp::socket *s=new boost::asio::ip::tcp::socket(ios);
sockets.push_back(s);
acceptor_.async_accept(*s,
boost::bind(&server::handle_accept, this,
boost::asio::placeholders::error));
}
void server::handle_accept(const boost::system::error_code& e)
{
if(e)
{
std::cerr<<"e.message() = "<<e.message()<<std::endl;
boost::asio::ip::tcp::socket *s=sockets.back();
s->close();
delete s;
sockets.pop_back();
}
static int i=1;
std::cerr<<"i = "<<i++<<std::endl;
start_accept();
}
的main.cpp
#include "server.hpp"
int main()
{
server s;
s.run();
return 0;
}
我的测试是
for x in `seq $1`;do nc 127.0.0.1 5050 & done
答案 0 :(得分:1)
在server::handle_accept
结束时,即使套接字出错,也会将异步接受提交回IO服务队列。
我不确定这是你想要的,但我可以做到&#34;工作&#34; (恢复)通过在接受失败时重新启动监听器。 (请注意,如果在多个线程上运行服务,则需要进行一些同步。)
<强> Live On Coliru 强>
#include <boost/asio.hpp>
class server
{
public:
server();
void run();
private:
bool start_listen();
void start_accept();
void handle_accept(boost::system::error_code e);
boost::asio::io_service ios;
boost::asio::ip::tcp::acceptor acceptor_;
std::vector<boost::asio::ip::tcp::socket*> sockets;
};
#include <boost/bind.hpp>
server::server(): acceptor_(ios)
{
start_listen();
start_accept();
}
void server::run()
{
ios.run();
}
bool server::start_listen()
{
boost::system::error_code e;
boost::asio::ip::tcp::endpoint endpoint { {}, 5050 };
acceptor_.open(endpoint.protocol());
acceptor_.set_option(boost::asio::ip::tcp::acceptor::reuse_address(true));
acceptor_.bind(endpoint, e);
if (e)
return false;
acceptor_.listen();
return true;
}
void server::start_accept()
{
boost::asio::ip::tcp::socket *s=new boost::asio::ip::tcp::socket(ios);
sockets.push_back(s);
acceptor_.async_accept(*s, boost::bind(&server::handle_accept, this, boost::asio::placeholders::error));
}
#include <iostream>
void server::handle_accept(boost::system::error_code e)
{
if(e)
{
std::cerr<<"e.message() = "<<e.message()<<std::endl;
boost::asio::ip::tcp::socket *s=sockets.back();
s->close();
delete s;
sockets.pop_back();
acceptor_.close();
if (!start_listen())
return;
}
static int i=1;
std::cerr<<"i = "<<i++<<std::endl;
start_accept();
}
int main()
{
server s;
s.run();
}
答案 1 :(得分:0)
以这种方式打开套接字
boost::asio::ip::tcp::socket *s=new boost::asio::ip::tcp::socket(ios);
套接字未打开,只创建了一个对象。当您尝试接受它时,您会达到打开的文件描述符限制,因此您会收到“打开文件太多”错误。然后你只需从vector中删除它,然后创建另一个无法在accept中打开的套接字。我认为这是错误的原因。
更新: 顺便说一下,这个功能
void server::start_accept()
{
boost::asio::ip::tcp::socket *s=new boost::asio::ip::tcp::socket(ios);
sockets.push_back(s);
acceptor_.async_accept(*s,
boost::bind(&server::handle_accept, this,
boost::asio::placeholders::error));
}
似乎有可能的内存泄漏,如果在push_back
方法中生成异常,s
将丢失。
更新:如果以这种方式重写handle_accept,则修复inifinte循环:
void server::handle_accept(const boost::system::error_code& e)
{
if(e)
{
auto size = 2;
for (int i = 0; i < size; ++i) {
std::cerr<<"e.message() = "<<e.message()<<std::endl;
boost::asio::ip::tcp::socket *s=sockets.back();
s->close();
delete s;
sockets.pop_back();
}
}
static int i=1;
std::cerr<<"i = "<<i++<<std::endl;
start_accept();
}