Programmer Group

Problem description After the cluster upgrade, hadoop cannot load the local library normally $ hadoop checknative -a 20/05/08 14:32:11 WARN bzip2.Bzip2Factory: Failed to load/initialize native-bzip2 library system-native, will use pure-Java version 20/05/08 14:32:11 WARN zlib.ZlibFactory: Failed to load/initialize native-zlib library 20/05/08 1 ...

The framework is to leave the complex to itself, the simple to coden, as simple as writing hello world When developing Spring AOP programs in the early years, aop was configured with xml files (now xml is not popular, annotation @ EnableAspectJAutoProxy is popular), and then framework parsing, For example: How is this configuration reso ...

0 core problem of creating thread pool According to one of Alibaba's Java development specifications, This rule points out that when we want to use the thread pool, we'd better not be lazy. We'd better create the thread pool by ourselves manually. Then the problem is, how to create the thread pool man ...

1. Build os basic mirror 1) Make your own os mirror Dockerfile, note that the first letter "D" of the Dockerfile name must be capitalized, otherwise it will not be recognized when you build it [root@k8s centos7.6]# cat Dockerfile #Basic Mirror Source, download centos:7.6.1810 in dockerhub beforehand FROM centos:7.6.1810 ...

The basic data type wrapper class is introduced here. Integer is the wrapper class of int, The methods of wrapper classes of other basic data types are almost the same as those of Integer, and one of them can be used for plenary session Characteristics of basic data type wrapper class: used for conversion between basic data type and string Thes ...

1. Description of RandomAccessFile class in JDK API   Instances of this class support reading and writing to random access files. Random access to a file behaves like a large array of bytes stored in the file system. There is a cursor or index to the implicit array, which is called a file pointer; the input operation reads bytes from the fi ...

From: http://blog.csdn.net/bing Bing a/article/details/53130341 MyEclipse installation configuration is divided into the following steps: 1, Install JDK and configure environment variables: [MyEclipse installation and configuration tutorial] 1. Install JDK and configure the environment variable - blog - blog Channel - CSDN.NET http:// ...

background In the high concurrency scenario of the Internet, there will be a lot of requests, but the database connection pool is relatively small, or the CPU pressure and processing logic need to be reduced. It is necessary to change a single query to batch query multiple and return. For example, in Alipay, query "personal information&quo ...

This paper mainly introduces the influence of automatic unpacking and boxing on the performance of operation from the perspective of bytecode and memory occupation. If you want to understand bytecode, you need to understand the structure of JVM virtual machine stack and code execution process. Please refer to "deep understanding of Java vi ...

  In the Alibaba java Development Manual, it is pointed out that thread resources must be provided through thread pools, which do not allow the creation of threads displayed by the application itself. On the one hand, the creation of threads is more standardized and the number of open threads can be reasonably controlled. On the other hand, th ...