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xml file bad instructions do not allow matching Problem description The xml file in Eclipse reported the following error: The processing instruction target matching "[xX][mM][lL]" is not allowed. The error file is empty-configuration.xml in hadoop-common project in Hadoop 2.7.1 source code. The directory of this file in the project is as f ...

Layer of docker image _Each instruction in the Dockerfile creates a new mirror layer;_Mirror layers will be cached and reused;_When the instructions of the Dockerfile are modified, the copied file changes, or the variables specified when the image is built are different, the corresponding mirror layer cache will fail;_When the mirror cache of ...

By default, the plug-in spring boot Maven plugin packages the whole project into a Jar package that can run (the so-called Flat Jar), resulting in a large Jar package (usually dozens of M +). Nowadays, there are many things in iterative publishing. It will waste a lot of time to upload such a huge file every time, and sometimes there will be er ...

JAVA technology exchange QQ group: 170933152  Take a look at the figure below. Execute two commands. First find the pid of tomcat, and then find the port according to the pid   It can be seen as follows: 1. Check the process number of tomcat first ps -ef | grep tomcat* The * sign is followed to view multiple tomcat, such ...

I will not repeat the installation of Arthas here, but I will use it directly Official website address: https://alibaba.github.io/arthas/ 1. View thread information thread View the current thread information and the thread stack Parameter description Parameter name Parameter description id Thread id [n:] ...

order This article mainly studies the DLedgerRoleChangeHandler of rocketmq. DLedgerRoleChangeHandler rocketmq-all-4.6.0-source-release/broker/src/main/java/org/apache/rocketmq/broker/dledger/DLedgerRoleChangeHandler.java public class DLedgerRoleChangeHandler implements DLedgerLeaderElector.RoleChangeHandler { private static final InternalL ...

1. apapche user authentication: you need to enter a user name and password when you visit the website, and you can access it only after the authentication is passed, which increases the security: for example, manage the access to the background: 1. First, make authentication for the root directory: that is to say, when you visit the website, y ...

Case 1: rpm deployment and installation of httpd (1) Modify the configuration file and create the base directory [root@server4 salt]# vim /etc/salt/master [root@server4 salt]# cd [root@server4 ~]# ls anaconda-ks.cfg install.log install.log.syslog [root@server4 ~]# mkdir /srv/salt [root@server4 ~]# /etc/init.d/salt-master ...

Hbase provides multilingual calls through thrift, a cross language RPC framework. Hbase has two sets of thrift interfaces (thrift1 and thrift2), but they are not compatible. According to the official documents, thrift1 is likely to be abandoned. This article takes thrift2 integration as an example. 1. Visit http://thrift.apache.org/download to ...

Source code https://github.com/zhongchengyi/zhongcy.demos/tree/master/mongo-morphia-demo Preface Morphia is a library that java uses orm to operate mongodb. But by default, when using morphia to access enum, it is accessed by name. We need to access enum by value. As shown in the figure: the schoolClassLevel1 field is accessed by enum name ...