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  How to do pprof for gRPC service

gRPC is a RPC framework based on HTTP and is frequently used for communications among micro service inside the same organization network. However,  the service functions cannot be accessed via normal HTTP URL as it's not a WEB framework. In this case, how to do pprof on a gRPC service? The trick is starting a HTTP server asynchronously while starting the gRPC service. This HTTP server can be accessed to run prrof debug. go func(){ http.ListenAndServe(":10001", nil) }() Since it uses the de...

   GOLANG,PPROF,GRPC     2021-01-29 23:11:33

  What can .htaccess file do?

A .htaccess file is a directory-level configuration file supported by several web servers, that allows for decentralized management of web server configuration. What can a .htaccess file do? We summarized some of them here.  Hope it may help you. 1. Timezone settingSometimes when you use date() or mktime() functions in PHP, , it may display some weird information because of the timezone difference. For example, one possible warning is :Warning: date(): It is not safe to rely on the syste...

   .htaccess,setting,tip     2012-06-15 06:39:39

  HTML5 History of 20th Century Music

We've seen some neat interactive HTML5 infographics before -- but the periodic table, for example, doesn't really care that much about time.Visual representation of time introduces numerous complications. Traditional ways of representing time visually were, roughly speaking, translations of dimension-type, from temporal to spatial; the mapping selected would depend on what kind of temporal relation was meaningful for the particular application. For example, circles represent cyclical beha...

   HTML5,JavaScript,Music,Timeline     2011-12-16 09:35:55

  What to put on whiteboard during an interview

As a programmer, you may go through different kinds of programming tests while interviewing for jobs. The most famous and difficult one may be the whiteboard test for lots of people. Usually the interviewer will give the candidate an algorithm problem or case study and ask the candidate to implement the algorithm with his/her favorite programming language. The code to be written is not too much but it requires the candidate to thoroughly consider different edge cases. So wha...

   TIPS,INTERVIEW,WHITEBOARD TEST     2014-08-29 20:34:52

  Removing duplicates in sql

In modern web development, it’s standard practice to make use of a database abstraction layer, typically an Object-Relational Mapper based on either the Active Record pattern or the Data Mapper pattern. There are several pros and cons to this which are fairly well established, so I’ll spare us all from enumerating them all right now. One established pro worth mentioning is that these systems typically provide a high level interface for fetching data, often removing the need to ...

   SQL,Duplicate,Remove,Web design     2012-01-05 08:20:13

  MySQL index optimization

Problem description: We need to access a very big table which has 40 million records. In the table, id is the primary key and program_id is indexed. When executing a select query: select * from program_access_log where program_id between 1 and 4000 The above query executes very slowly, we thought it was because there were too many records in the table. So we added id in the where condition to limit the search so that each time only half a million records would be read. select * fr...

   MySQL,Index search, Partition     2012-12-26 13:14:20

  Some tricks and tips for using for range in GoLang

GoLang provides two major ways to loop through elements of array, slice and map. They are for and for range. Many people find that for range is very convenient when don't care about the index of the element. In this post, some tricks and tips would be talked about regarding for range. 1. Loop and get pointer of each element Assume there is a code snippet like below which is to get the pointer of each element in an array and create a new array with the corresponding pointer. arr := [2]int{1, 2} r...

   POINTER,FOR LOOP,GOLANG,FOR RANGE     2020-03-08 01:07:00

  Why accessing Java HashMap may cause infinite loop in concurrent environment

HashMap in Java is frequently used to handle key/value pairs. But it is not a good candidate to be used in concurrent environment where ConcurrentHashMap should be used instead. If used in concurrent environment, it may cause lots of unexpected behavior even including make the program getting into an infinite loop situation. To understand how this can happen, let's first discuss how HaspMap works internally. In this post we will use implementation of HashMap before Java 8 as example, Java 8 prov...

   JAVA,HASHMAP,INFINITE LOOP     2020-03-29 01:47:00

  Understanding an interesting JavaScript map function question

With the evolvement of JavaScript, lots of new features have been added this old but robust language.  Among them are lots of functional programming language related functions like map, filter, each etc. In this post, we will cover one function map and its interesting behavior. Before dive into the details, let first take an example, do you know the output of below function call? ['1', '7', '11'].map(parseInt) You may think that it's easy and the output would be [1, 7, 11] Can you try to ru...

   JAVASCRIPT,MAP,FUNCTIONAL PROGRAMMING     2019-06-14 08:34:46

  Find the kth smallest number in an array

This is an classical question, the general solution to this question is first using sorting algorithm to sort the array, then get the kth number in the array, the complexity is O(nlogn), we can also use selective sort or head sort to, the complexity of selective sort is O(kn) and heap sort is O(nlogk). The better solution is to use quick sort to find the kth smallest number, the complexity is O(n), the worst case cost is O(n^2). But today we introduce one more solution which has the worst case c...

   Sort, Quick sort, Search,Smallest     2013-01-09 06:20:54

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