iocp

IOCP threads - Clarification?

由 走远了吗. 提交于 2020-01-12 01:34:08
问题 After reading this article which states : After a device finishes its job , (IO operation)- it notifies the CPU via interrupt. ... ... ... However, that “completion” status only exists at the OS level; the process has its own memory space that must be notified ... ... ... Since the library/BCL is using the standard P/Invoke overlapped I/O system, it has already registered the handle with the I/O Completion Port (IOCP), which is part of the thread pool. ... ... ... So an I/O thread pool thread

IOCP threads - Clarification?

由 核能气质少年 提交于 2020-01-12 01:34:08
问题 After reading this article which states : After a device finishes its job , (IO operation)- it notifies the CPU via interrupt. ... ... ... However, that “completion” status only exists at the OS level; the process has its own memory space that must be notified ... ... ... Since the library/BCL is using the standard P/Invoke overlapped I/O system, it has already registered the handle with the I/O Completion Port (IOCP), which is part of the thread pool. ... ... ... So an I/O thread pool thread

受”误解“的Java AIO

由 天大地大妈咪最大 提交于 2020-01-08 18:20:39
【推荐】2019 Java 开发者跳槽指南.pdf(吐血整理) >>> 为什么说 AIO 受”误解“，虽然这个”误解“被打上了双引号，但还是不得不承认它的发展状况并不好。AIO 是 Java 7 开始提供的新特性，而这个”新特性“到如今都成了陈年老酒还鲜有人去品味它。要知道 Java 7 可是在 2011年7月份发布的，市面上基于 AIO 实现的通信框架竟然寥寥无几，关于这项技术的介绍文章也普遍比较粗略。通过阅读那些介绍 AIO 的文章，似乎从学术层面大家就不怎么待见这项技术。 作为 AIO 的学习者、受益者，我觉得有必要先对网上的一些 ”偏见“ 表达一下自己的观点。如果能有幸在认知上搭成共识，之后的学习交流会更加顺畅一点。通常偏见源于比较，AIO 与 BIO、NIO 的对比明细如表所示。 BIO NIO AIO 客户端 : I/O 线程数 1 : 1 N : 1 N : 0 I/O类型 同步阻塞 同步非阻塞 异步非阻塞 API使用难度 简单 复杂 一般 调试难度 简单 复杂 一般 可靠性 差 高 高 吞吐量 低 高 高 适用场景 适用于连接数量不多，并发量不高的场景。充分发挥易编程的优势。 适用于对连接数量以及稳定性、实时性有较高要求的场景，采用 NIO 或 AIO 能有效缓解网络 I/O 造成的机器负载。 同NIO 误解一 通过上表的比较可以看出 AIO 的性价比应该是优于

windows重叠IO和IOCP简介

由 大憨熊 提交于 2020-01-06 23:05:15
产生重叠IO的原因： 对于阻塞IO的读写操作都是需要阻塞等待IO完成的，大大的浪费用户的进程的时间片，降低了程序的性能。所以系统开个后门，悄悄地给你开个后门，开个线程去帮你请求IO，等到IO操作完成之后再通知你，你就可一再接着处理就好了，那么在IO完成之前你就可以放心的做其他的了。 重叠IO的重要数据结构： typedef struct _WSAOVERLAPPED { DWORD Internal ; DWORD InternalHigh ; DWORD Offset ; DWORD OffsetHigh ; WSAEVENT hEvent ; } WSAOVERLAPPED , * LPWSAOVERLAPPED ; 详细请见msdn WSAEVENT hEvent是连接完成事件和用户程序的桥梁，我们可以通过可爱的waitformultipleobjects和waitforsingleobject来接受通知，进而处理完成事件。 那么，IOCP又是怎么一肥事呢？ 需要知道，重叠IO解放劳动力的同时，也是有代价的，如果1000个请求同时发生就需要系统内部开启1000个线程去处理IO，那么负载实在太大了，所以需要池化，为用户进程开线程池去优化IO请求咯。 注意： 使用重叠IO或者IOCP之前IO句柄或者Socket创建的时候需要置位WSA_FLAG_OVERLAPPED标志。

Connecting to IOCP server in Java (Android)

由 人走茶凉 提交于 2020-01-06 19:56:49
问题 I'd like to make an Online Game with Android. I'm planning to make Server with IOCP model via C++. This should work fine, the problem is the client. IOCP client example in C++ uses WSASyncselect or WSAEventSelect . I couldn't find any Java examples that same work like async socket. Questions: Is there anything like WSASyncselect() in Java? If not that, how could i do it? 回答1: The JDK 7 Windows implementation of the Java 7 "NIO.2" classes AsynchronousSocketChannel

Do .NET 4.5 Server-Side WebSockets use IOCP?

由 白昼怎懂夜的黑 提交于 2020-01-06 18:11:26
问题 Does anyone know if AspNetWebSocket (introduced in .NET Framework 4.5) utilizes IOCP for handling requests instead of one thread per Connection? 回答1: There's a relatively easy way for you to work this out for yourself. Create a simple program. Watch it with a task monitor and look at the number of threads. Create lots of web socket connections to it. See if the thread count increases whilst the connections are alive. Compare the number of connections to the number of threads. But, what does

Do .NET 4.5 Server-Side WebSockets use IOCP?

由 夙愿已清 提交于 2020-01-06 18:10:28
问题 Does anyone know if AspNetWebSocket (introduced in .NET Framework 4.5) utilizes IOCP for handling requests instead of one thread per Connection? 回答1: There's a relatively easy way for you to work this out for yourself. Create a simple program. Watch it with a task monitor and look at the number of threads. Create lots of web socket connections to it. See if the thread count increases whilst the connections are alive. Compare the number of connections to the number of threads. But, what does

IOCP multithreaded server and reference counted class

由 倖福魔咒の 提交于 2020-01-04 09:04:45
问题 I work on IOCP Server (Overlapped I/O , 4 threads, CreateIoCompletionPort, GetQueuedCompletionStatus, WSASend etc). And my goal is to send single reference counted buffer too all connected sockets.(I followed Len Holgate's suggestion from this post WSAsend to all connected socket in multithreaded iocp server) . After sending buffer to all connected clients it should be deleted. this is class with buffer to be send class refbuf { private: int m_nLength; int m_wsk; char *m_pnData; // buffer to

How to find out when CancelIo() is done?

由 ε祈祈猫儿з 提交于 2020-01-04 05:57:27
问题 CancelIo() is supposed to cancel all pending I/O operations associated with the calling thread. In my experience, CancelIo() sometimes cancels future I/O operations as well. Given: ReadFile(port, buffer, length, &bytesTransferred, overlapped); If I invoke CancelIo(port) immediately before the read, GetQueuedCompletionStatus() will block forever, never receiving the read operation. If I invoke CancelIo(port) immediately after the read, GetQueuedCompletionStatus() will return 0 with

casting issue with linked list item

由 别等时光非礼了梦想. 提交于 2020-01-03 04:54:22
问题 This is my PER_IO_CONTEXT structure (i stored them in singly linked list): typedef struct _PER_IO_CONTEXT { SLIST_ENTRY ItemEntry; WSAOVERLAPPED Overlapped; WSABUF wsabuf; /* some other data*/ } PER_IO_CONTEXT, *PPER_IO_CONTEXT; and below is WSAsend , that use the list for getting WSAOVERLAPPED structure: ... PSLIST_HEADER pListHead; ... PSLIST_ENTRY pListEntry = InterlockedPopEntrySList(pListHead); PPER_IO_CONTEXT ovl = (PPER_IO_CONTEXT)pListEntry; WSASend(pTmp1->Socket,..., &(ovl-
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