epoll | 易学教程

Why does select.select() work with disk files but not epoll()?

阅读更多关于 Why does select.select() work with disk files but not epoll()?

问题 The following code essentially cats a file with select.select(): f = open('node.py') fd = f.fileno() while True: r, w, e = select.select([fd], [], []) print '>', repr(os.read(fd, 10)) time.sleep(1) When I try a similar thing with epoll I get an error: self._impl.register(fd, events | self.ERROR) IOError: [Errno 1] Operation not permitted I've also read that epoll does not support disk files -- or perhaps that it doesn't make sense. Epoll on regular files But why does select() support disk

select vs poll vs epoll [closed]

阅读更多关于 select vs poll vs epoll [closed]

问题 As it currently stands, this question is not a good fit for our Q&A format. We expect answers to be supported by facts, references, or expertise, but this question will likely solicit debate, arguments, polling, or extended discussion. If you feel that this question can be improved and possibly reopened, visit the help center for guidance. Closed 7 years ago . I am designing a new server which needs to support thousands of UDP connections (somewhere around 100,000 sessions). Any input or

jstack（Cat消息消费机器CPU消耗过高问题分析）

阅读更多关于 jstack（Cat消息消费机器CPU消耗过高问题分析）

【推荐】2019 Java 开发者跳槽指南.pdf(吐血整理) >>> 1、找出当前CPU资源消耗最大的进程用top命令，发现java进程（pid:8424）CPU资源消耗达到192%,如下图：确定java资源消耗过多。 2、打印当前JVM堆栈 jstack 8424 > /tmp/jstack.txt 堆栈信息见附件1 3、找到当前堆栈资源消耗多的线程命令如下： top -H -p8424 结果如下： 8320 nwd 20 0 6275m 4.8g 7044 R 44.6 62.7 3:57.00 java 8365 nwd 20 0 6275m 4.8g 7044 R 32.4 62.7 4:06.09 java 19016 nwd 20 0 6275m 4.8g 7044 R 22.5 62.7 0:24.47 java 8289 nwd 20 0 6275m 4.8g 7044 S 14.1 62.7 16:27.13 java 8356 nwd 20 0 6275m 4.8g 7044 S 13.5 62.7 6:40.18 java 8333 nwd 20 0 6275m 4.8g 7044 R 10.3 62.7 5:21.39 java 从上面查询出来的结果可以找到cpu消耗靠前的线程的pid，下一步根据pid从堆栈里面查找相应的线程。注意

对socket的代码学习和自我理解与记录 epoll模式

阅读更多关于对socket的代码学习和自我理解与记录 epoll模式

【推荐】2019 Java 开发者跳槽指南.pdf(吐血整理) >>> epoll模式主要就是直接对socket进行监听，不需要轮询，如果socket有状态变化就会触发 <?php class Worker{ //监听socket protected $socket = NULL; //连接事件回调 public $onConnect = NULL; //接收消息事件回调 public $onMessage = NULL; public $workerNum=4; //子进程个数 public $allSocket; //存放所有socket public function __construct($socket_address) { //监听地址+端口 $this->socket=stream_socket_server($socket_address); } public function start() { //获取配置文件 $this->fork(); } public function fork(){ $this->accept();//子进程负责接收客户端请求 } public function accept(){ //第一个需要监听的事件(服务端socket的事件),一旦监听到可读事件之后会触发 swoole_event_add($this->socket

how to detect TCP keep alive packets and keep connection open

阅读更多关于 how to detect TCP keep alive packets and keep connection open

问题 I wrote my own server with epoll. When I sent TCP keep alive packages from client to server, epoll event will not get triggered. Question: I want my server to keep the connection open when server gets tcp keep alive packages. I also tried to look at tcp info but there are no update for its attributes when server got keep alive packages. I understand tcp keep alive packages is no data but header. I saw in my tcpdump, kernel sent back tcp keep alive ACK after received keep alive package. My

Epoll: does it silently remove fds?

阅读更多关于 Epoll: does it silently remove fds?

问题 I've been reading through libev's source code and stumbled upon this comment: a) epoll silently removes fds from the fd set. as nothing tells us that an fd has been removed otherwise, we have to continually "rearm" fds that we suspect might have changed (same problem with kqueue, but much less costly there). I've been doing some tests with epoll (directly using syscalls) on some modern linux kernel and I couldn't reproduce it. I didn't see any problem with "silently disappearing fds". Could

When recv blocks?

阅读更多关于 When recv blocks?

问题 The goal is to read data from a socket without blocking. The Linux manual page says: The receive calls normally return any data available, up to the requested amount, rather than waiting for receipt of the full amount requested. Does it mean that I don't have to pass MSG_DONTWAIT flag to recv() after polling the socket descriptor with select() / poll() / epoll() ? 回答1: The behaviour of recv / read depends on the characteristics of the socket itself. If the socket is marked as non-blocking,

Time out idle connections in epoll based server

阅读更多关于 Time out idle connections in epoll based server

问题 I'm writing a tcp server in c that uses epoll() i/o multiplexing to manage concurrent connections. I want to timeout connections that have been idle for more than an allowed time. So far I keep a last_active time_t variable associated with each connection, which I update to the current time in the event handler. Before doing that, I check if more than the allowed time has ellapsed since last event and if so I terminate the connection. So far so good but it's not really what I want because the

epoll exception handle

阅读更多关于 epoll exception handle

问题 I am working on a network programming using epoll. I was wondering a situation that server didn't receive all the data client sent. For example if a client sent 100 bytes and somehow server only received 94bytes. How do I handle this case? Thanks in advance.. 回答1: An epoll signals readiness , it does not give any guarantees about the amount of data. EPOLLIN only gives to you the guarantee that the next read operation on the descriptor will not block and will at least read 1 byte. As one

10万并发的高性能c++ webserver设计与实现

阅读更多关于 10万并发的高性能c++ webserver设计与实现

简介该项目使用c++11，参考muduo实现的静态web服务器。muduo网络库使用线程池+电平触发式epoll+NIO的Reactor模式实现。该项目汲取muduo的优点，并简化设计。采用线程池+边沿触发式epoll+NIO的Reactor模式实现，各个工作线程采用RR方式(Round Robin)来公平分配请求，同时引入了应用层心跳，来处理超时连接。该webserver支持长、短连接，采用被动式关闭，能优雅的断开连接。该项目参考muduo网络库Tcp骨架，针对Http协议处理过程设计而成。主要引入了HttpServer、HttpConnection和HttpHandler和HttpManager几个类，已应对接受Http请求、解析Http请求、应答Http请求以及管控Http连接的需要。采用压力测试工具webbench 1.5，实验得出：采用环回地址测试时，在10k长连接状态下，60s能处理1500w+个请求，响应能力为35 M/s。采用局域网地址测试时，在10k长连接状态下，60s能处理750w+个请求，响应能力为1.67 M/s。启动webserver时内存占用为1.8MB；10k长连接下，平均占用15MB内存。为方便测试，该项目也加入了简易的资源监控脚本、内存泄露检测脚本、一键启动webserver脚本，以及压力测试脚本。目录结构 ├── code │ ├──