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Arthas is a Java diagnostic tool open source by Alibaba in September 2018. It supports JDK6 + and adopts command-line interaction mode, which can easily locate and diagnose online program operation problems. The official document of Arthas is very detailed. See: https://alibaba.github.io/arthas Arthas usage scenario Thanks to the powerful ...

1, Read write separation concept Read write separation is to evenly distribute query requests to multiple data copies through master-slave configuration, so as to further improve the processing capacity of the system. Master-slave architecture: read-write separation, which aims at high availability and read-write expansion. The contents of t ...

prefaceUnlike Java and other languages, JavaScript does not have any printing or output methods. It usually uses the following four ways to output data.Use window Alert() is used to pop up a warning boxUse document Write() writes the content to the HTML documentUse innerHTML to write to HTML elementsUse console Log() is written to the browser c ...

background Are you still writing about explosions on the screen? That is, regardless of 3721, write all the code in one class, so the code is not elegant. If the change involves the old code, it may also affect the stability of the online system. In fact, in many cases, we can solve many potential system problems by skillfully using the desi ...

Preface: introduce a simple MyBatis encryption and decryption method. This method is rarely mentioned in daily study and work, so let's talk about it. If you already know this method, ignore this article 1, Background Sometimes in our database, some sensitive information of users, such as mobile phone number, bank card and other information, ...

catalogue 1. Basic concept and definition of inheritance 1.1 basic concept of inheritance 1.2 definition of succession 2. Assignment conversion of base class and derived class objects 3. Scope in inheritance  4. Default member function of derived class 4.1 calling order of constructor destructor of base class derived class ...

1 simulate document tree structure 2 how to get elements 1) Get element by id var div1 = document.getElementById("box1"); 2) Get element by class name var p1Arr = document.getElementsByClassName("p1"); Pseudo array definition: 1. It has the length attribute, and other attributes (indexes) are non negative integers (the index in the objec ...

Pytorch Sampler When training neural network, if the amount of data is too large to put the data into the network for training at one time, it is necessary to read the data in batches. This problem involves how to read data from the data set. PyTorch framework provides Sampler base class and multiple subclasses to realize data sampling in ...

shiro (java security framework) 1 Introduction Apache Shiro is a security framework for Java. At present, more and more people use Apache Shiro because it is quite simple. Compared with Spring Security, it may not be as powerful as Spring Security, but it may not need so complex things in actual work, so using a small and simple Shiro is enou ...

Binary tree - preorder traversal (middle left right) recursion # Definition for a binary tree node. # class TreeNode: # def __init__(self, val=0, left=None, right=None): # self.val = val # self.left = left # self.right = right class Solution: def preorderTraversal(self, root: TreeNode) -> List[int]: ...