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preface As a supplement to the previous article, learn fastjson after half a year. Initial recognition of fastjson Fastjson is a Java library that can convert Java objects into JSON format. Of course, it can also convert JSON strings into Java objects. Fastjson can manipulate any Java object, even some pre-existing objects without source co ...

ELK log analysis 1, ELK introduction ELK platform is a complete set of centralized log processing solution, which combines ElasticSearch, Logstash and Kiabana, three open-source tools to meet the more powerful user requirements for log query, sorting and statistics. Elastic search: it is a distributed storage and retrieval engine based on L ...

1, You don't know hash tables 1. What is a hash table? We already know a data item, keyword mapping storage location.In fact, our search process is to compare and constantly compare keywords, so that we can find the storage location.Now you should find that they are like functions, X = keyword and Y = storage location.The difficulty of ha ...

1, Set up etcd cluster There are three main types of self building clusters: Static discovery: the nodes in the etcd cluster are known in advance. When starting, directly specify the addresses of each node of the etcd through the -- initial cluster parameter.Etcd dynamic discovery: the premise of static configuration is that the informati ...

Target information Download address: https://hackmyvm.eu/machines/machine.php?vm=Corrosion3 Range: hackmyvm eu Target name: Worrosion3 Difficulty: simple Release time: February 18, 2022 Prompt: nothing Target: 2 flag s Experimental environment Attack aircraft:VMware kali 192.168.7.3 Target plane:Vbox linux IP Automatic acquisit ...

1, Detailed explanation of foundation 1. Traditional IO(BIO) Traditional IO is stream oriented and synchronous blocking io. Each socket request needs to be processed by a corresponding thread. If there are not enough threads to process, the request is either waiting or rejected. That is, each connection requires the service to be processed by ...

Constant time operation If the execution time of an operation is not transferred by the specific sample size, each execution time is a fixed time. Such operations are called constant time operations. Common arithmetic operations (+, -, *, /,%, etc.)Common bit operations (> >, > > >, < <, |, &, ^, etc.)Assignment, comp ...

When do I need a lock? When there is only one thread in the program, there is no need to lock, but usually the actual code is not just a single thread, so the lock needs to be used at this time. What are the main scenarios related to the use of the lock? When multiple threads are reading the same dataWhen multiple threads write the same d ...

summary Anonymous function essence The essence of anonymous functions is still functions. They are the same except for the syntax of their definitions Note: it can only be used to implement functions with very simple functions Syntax: lambda parameter list: return value Convert to normal: def (formal parameter list): Return return value S ...

day12 function advanced 1. Anonymous function The essence of anonymous functions is still functions. They have different syntax for definition, and everything else is the same Note: anonymity can only be used to implement functions with very simple functions Syntax: Function name = lambda parameter list: return value Convert to normal: def ...