Tag:strategy

  • Design a modern cache

    Time:2020-3-9

    This article is from the contribution of Alibaba Group’s customer experience business group, which is almost based on the work scenario, and has done some research on caching, and translated an article for fellow Chinese to learn. Original: http://highscalability.com/bl Caching is a general method to improve performance. Now most of the cache implementations use classic […]

  • Introduction to reinforcement learning and Markov decision process

    Time:2020-3-9

    1. What is reinforcement learning Reinforcement learning (RL) is a very many concept that has been put forward in recent years. So, what is reinforcement learning? Reinforcement learning is a branch of machine learning, which is parallel with supervised learning and unsupervised learning. The definition is given in reference [1]: Reinforcement learning is learning what […]

  • Audit details of Oracle 11g and 12C

    Time:2020-3-2

    Recently, I have encountered some script induced audit related BUG, and I feel it is necessary to reorganize the audit mode of 11g and 12C, so I revised the previous notes according to the official website and sent them here. 1、 Opening of audit function: SQL> show parameter audit –There are four main parameters: AUDIT_TRAIL(default:DB) […]

  • Httpclientfactory (Part 4) in asp.net core 2.1 integrates Polly to realize instantaneous fault handling

    Time:2020-3-2

    Original: https://www.stevejgordon.co.uk/httpclientfactory-using-poly-for-transient-fault-handlingPublished in: June 2018 In the previous article in this series, I introduced the concept of outgoing middleware using delegating handlers registered with naming and type clients. Although this method can be used, the asp.net team hopes that in most cases we don’t have to build our own handlers manually. In some cases, the […]

  • Virtual transaction of vitu.ai

    Time:2020-3-1

    (1) Why is simulation trading important? Quantitative trading has been gradually applied in more and more asset fields, such as stocks, futures, options and fixed income, etc., so it is no exception in the blockchain world. Vitu.ai is the research platform of every digital asset investor. In the trading of digital assets, it is normal […]

  • Retry retry mechanism

    Time:2020-2-22

    There are two retry mechanisms: guava and spring. Guava retryer tool POM reference <dependency> <groupId>com.github.rholder</groupId> <artifactId>guava-retrying</artifactId> <version>2.0.0</version> </dependency> test method Retryer<Boolean> retryer = RetryerBuilder.<Boolean>newBuilder() .retryIfExceptionOfType(Exception.class) //Return false also need to retry .retryIfResult(Predicates.equalTo(false)) //Readjustment strategy .withWaitStrategy(WaitStrategies.fixedWait(1, TimeUnit.SECONDS)) //Number of attempts .withStopStrategy(StopStrategies.stopAfterAttempt(3)) .build(); try { //Executes the specified method. retryer.call(() -> { System.err.println(“do something…”); Throw new exception […]

  • Data processing [Swiss Army knife pandas guide]: 5. Data type and missing value

    Time:2020-2-21

    Reference source: vitu.ai Let’s load the data first. import pandas as pd pd.set_option(‘max_rows’, 5) import numpy as np melbourne_data = pd.read_csv(‘melb_data.csv’) melbourne_data.head() data type The data type of a column in a dataframe or series is called a dtype. You can use the dtype property to get the type of a specific column: melbourne_data.Price.dtype Or, […]

  • Be familiar with these high-frequency interview questions of redis. Don’t worry about the interview

    Time:2020-2-4

    1. What are the application scenarios of redis? cache: this should be the main function of redis, and it is also a necessary mechanism for large-scale websites. Reasonable use of cache can not only speed up data access, but also effectively reduce the pressure of back-end data sources. Share session: for some services that depend […]

  • Share several high-frequency redis interview questions, don’t worry about the interview

    Time:2020-2-3

    1. What are the application scenarios of redis? cache: this should be the main function of redis, and it is also a necessary mechanism for large-scale websites. Reasonable use of cache can not only speed up data access, but also effectively reduce the pressure of back-end data sources. Share session: for some services that depend […]

  • GuavaCache

    Time:2020-2-3

    Google Guava LocalLoadingCache Preface In the process of programming, we will encounter some data that needs to be retried in the program. In this case, we can consider using the advantages of cache (memory) to provide a performance for the program to access these data. Using cache can alleviate a lot of performance consumption to […]

  • Determination of sample quantity in SAP QM inspection lot

    Time:2020-1-31

      Determination of sample quantity in SAP QM inspection lot The following inspection lot 890000045939,   The number of samples is 50 PC. Check the inspection plan corresponding to the inspection lot,     These inspection characteristics have their own sampling strategies. The relevant sampling quantity is reflected in the result entry interface,     […]

  • MySQL installation

    Time:2020-1-23

    Install from Yum repository at https://dev.mysql.com/downloads/repo/yum/ 2. Download RPM file wget https://dev.mysql.com/get/mysql80-community-release-el7-3.noarch.rpm 3. Please refer to https://dev.mysql.com/doc/mysql-yum-repo-quick-guide/en/install mysql5.7 Adding the MySQL Yum Repository rpm -Uvh mysql80-community-release-el7-3.noarch.rpm [[email protected] home]# rpm -Uvh mysql80-community-release-el7-3.noarch.rpm warning: mysql80-community-release-el7-3.noarch.rpm: Header V3 DSA/SHA1 Signature, key ID 5072e1f5: NOKEY Preparing… ################################# [100%] Updating / installing… 1:mysql80-community-release-el7-3 ################################# [100%] View the current MySQL version […]