heartbeat

各种软件的含义和特点

由 主宰稳场 提交于 2019-12-05 04:29:50
一、 heartbeat的概念 Linux-HA的全称是High-Availability Linux，它是一个开源项目，这个开源项目的目标是：通过社区开发者的共同努力，提供一个增强linux可靠性（reliability）、可用性 （availability）和可服务性（serviceability）（RAS）的群集解决方案。其中Heartbeat就是Linux-HA项目中 的一个组件，也是目前开源HA项目中最成功的一个例子，它提供了所有 HA 软件所需要的基本功能，比如心跳检测和资源接管、监测群集中的系统服务、在群集中的节点间转移共享 IP 地址的所有者等，自1999年开始到现在，Heartbeat在行业内得到了广泛的应用，也发行了很多的版本，可以从Linux-HA的官方网站www.linux-ha.org下载到Heartbeat的最新版本。 二、 HA集群中的相关术语 1．节点（node） 运行heartbeat进程的一个独立主机，称为节点，节点是HA的核心组成部分，每个节点上运行着操作系统和heartbeat软件服务，在 heartbeat集群中，节点有主次之分，分别称为主节点和备用/备份节点，每个节点拥有唯一的主机名，并且拥有属于自己的一组资源，例如，磁盘、文件 系统、网络地址和应用服务等。主节点上一般运行着一个或多个应用服务。而备用节点一般处于监控状态。 2．资源

setTimeOut() is not working with AJAX [duplicate]

由 一个人想着一个人 提交于 2019-12-04 19:26:57
This question already has answers here : Why is my function call that should be scheduled by setTimeout executed immediately? [duplicate] (3 answers) Closed 5 years ago . In my application i want to send something to the server after some time. I have implemented it using AJAX. But it works for the first time but not doing it recursively. I have used setTimeOut() for doing that. var xmlHttp; var requestURL = 'http://localhost:1092/ClassicAJAXDemo/UpdateHeartbeat.aspx?name='; function show_data(strName) { if (strName.length > 0) { var url = requestURL + strName; xmlHttp = GetXmlHttpObject

远离故障的十大原则

由 橙三吉。 提交于 2019-12-04 13:24:49
原文引用： http://www.woqutech.com/?p=714 故障是运维人员永远的痛。相信每一个运维人员的KPI中都有一项：可用性。可用性高就是不出故障，各个公司对可用性和故障评级的标准都不相同，但是避免故障的方法却是殊途同归。我们怎么避免故障，沃趣科技简单列举了以下几条，与大家共勉！ 1、变更要有回滚，在同样的环境测试过 2、对破坏性的操作谨慎小心 3、设置好命令提示 4、备份并验证备份有效性 5、对生产环境存有敬畏之心 6、交接和休假最容易出故障，变更请谨慎 7、搭建报警，及时获得出错信息。 8、自动切换需谨慎 9、仔细一点，偏执一点，检查，检查，再检查 10、简单即是美。 【远离故障的十大原则之1】变更要有回滚，在同样的环境测试过。 也是运维最繁琐，最苦逼的地方，所有的变更都必须有回滚的办法，在同样的环境下测试过。没有做过的东西，总是会在你意想不到的地方给你一次痛击，在阿里巴巴的这么多年运维经验告诉我们，所有没有做过的变更，出错的概率最大。所以我们需要给变更以回滚的可能，在各个步骤可能出错的情况下，考虑回滚到最初状态。优秀的运维人员对不考虑回滚的的操作都是敬而远之的。从某种意义上来说，运维是一门经验的学科，是一门试错的学科。 【远离故障的十大原则之2】对破坏性的操作谨慎小心。 破坏性的操作有哪些列？对数据库来说有：DROP Table， Drop database

WebSphere MQ - Changing channel definition structure using XMS.NET API

由 拈花ヽ惹草 提交于 2019-12-04 02:24:05
问题 I am trying to set the MQCD structure properties - specifically HeartBeatInterval using XMS.NET API. Background: I have client applications (in .NET) using XMS.NET API to read messages from WebSphere MQ. I use the ClientAcknowledge mode. If the client reads the message and does not ack it, WebSphere MQ waits for 300 seconds before timing out and makes (backout) the message available in the original queue for other clients to read the message. Task: I want to lower the timeout from 300 seconds

How to access Galaxy S5 heart rate sensor?

由 最后都变了- 提交于 2019-12-03 21:18:05
In the Samsung's programming guide (pages 77 - 81) there is a reference on how to set and get the heart rate information using the S Health Service SDK. However, I was looking to directly access the Galaxy S5's heart rate sensor, the same way you are able to access the accelerometer, gyroscope, light sensor, among other sensors. I found this example for the samsung gear live , but I cannot find any example for Galaxy S5. Is it possible to directly access the Galaxy S5's heart rate sensor? Does anyone has a code example on how to do it? Thank you. You cannot get raw heart rate monitor data from

Scalable algorithm to detect stale data

由 荒凉一梦 提交于 2019-12-03 21:02:18
Here is the problem: "Agents" installed on many different servers send "heartbeat" signals up to a central server every 5 seconds. How can I find the ones that have missed their heartbeat for more than 10 seconds actively and raise an alert? The problem is simple if you don't think about scalablity. In the simplest form, you can record the timestamp of the latest heartbeat received from each agent in a database table and run a regular query to find the ones older than the threshold. This solution is however not scalable to millions of agents. I am looking for algorithms or techologies that

how to measure HeartBeat using an android device [closed]

由 北战南征 提交于 2019-12-03 16:48:29
问题 It's difficult to tell what is being asked here. This question is ambiguous, vague, incomplete, overly broad, or rhetorical and cannot be reasonably answered in its current form. For help clarifying this question so that it can be reopened, visit the help center. Closed 7 years ago . My question is very simple and straight forward. Is there any technique through which i can calculate the heartbeat of a person using android device. I googled it and found some results in which they implemented

In Socket.IO, is 'heartbeat' an event that can be used to trigger other actions?

由 穿精又带淫゛_ 提交于 2019-12-03 12:34:42
问题 This exact code doesn't work, but, I was hoping something like it was: io.sockets.on('connection', function(socket) { socket.on('heartbeat', function() { // Do something here... }); }); Is something like this possible? I mean, I know I can just make a different function that triggers every, say, 15 seconds using a setInterval: io.sockets.on('connection', function(socket) { setInterval(function() { // Do something },15000); }); But since the heartbeat is already running at this interval, why

rabbitmq——heartbeat

由 ￣綄美尐妖づ 提交于 2019-12-03 09:27:29
heartbeat通常用来检测通信的对端是否存活（未正常关闭socket连接而异常crash）。其基本原理是检测对应的socket连接上数据的收发是否正常，如果一段时间内没有收发数据，则向对端发送一个心跳检测包，如果一段时间内没有回应则认为心跳超时，即认为对端可能异常crash了。 rabbitmq也不例外，heatbeat在客户端和服务端之间用于检测对端是否正常，即客户端与服务端之间的tcp链接是否正常。 1. heartbeat检测时间间隔的设置 1). 服务端的设置 heartbeat检测时间间隔可在配置文件rabbitmq.config中增加配置项{heartbeat,Timeout}进行配置，其中Timeout指定时间间隔，单位为秒。 例如: 如果没有进行配置，默认的时间间隔为600秒（最新版本3.2.2修改为580秒） 在rabbit.app中有heartbeat的配置项。 2). 客户端的设置 根据AMQP协议，rabbitmq会通过connection.tune信令将heartbeat检测时间间隔告知客户端，客户端可以根据需要重新设置该值，并通过Connection.tune-ok信令将时间间隔再告诉给rabbitmq，rabbitmq会以客户端的时间作为该tcp连接上heartbeat检测的间隔时间。 这里要注意的是：如果时间间隔配置为0

AWS Cloudwatch Heartbeat Alarm

由 匿名 (未验证) 提交于 2019-12-03 08:41:19
可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 问题: I have an app that puts a custom Cloudwatch metric to AWS every minute. This is supposed to act as a heartbeat so I know the app is alive. Now I want to put an alarm on this metric to notify me if the heartbeat stops. I have tried to accomplish this using different cloudwatch alarm statistics including "average" and "data samples" and setting an alarm threshold less than 1 over a given period. However, in all cases, if my app dies and stops reporting the heartbeat, the alarm will only go into an "Insufficient Data" state and never into an
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