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  10 Points about Java heap memory

When I started java programming I didn't know what is java heap or what is heap space in Java, I was even not aware of where does object in Java gets created, it’s when I started doing professional programming I came across error java.lang.outofmemoryerror then I realized What is Heap in Java or Java Heap Space. Its happens with most of programmer because learning language is easy but learning basics is difficult since there is no formal process which can teach you every basics of pro...

   Java,Heap memory,Tips     2012-02-20 05:38:06

  Find max subarray of an array

In computer science, the maximum subarray problem is the task of finding the contiguous subarray within a one-dimensional array of numbers (containing at least one positive number) which has the largest sum. For example, for the sequence of values −2, 1, −3, 4, −1, 2, 1, −5, 4; the contiguous subarray with the largest sum is 4, −1, 2, 1, with sum 6. The problem was first posed by Ulf Grenander of Brown University in 1977,...

   Max Subarray, Divide and conquer,Kadane     2013-04-22 11:50:35

  Why init() is not recommended in Go

golangci lint Currently, the unified CI's .golangci.yml includes the gochecknoinits checker: # golangci-lint v1.46.2 # https://golangci-lint.run/usage/linters linters: disable-all: true enable: ... - gochecknoinits # Checks that no init functions are present in Go code. ref: https://github.com/leighmcculloch/gochecknoinits ... If Go code uses the init() function, the following error will occur: # golangci-lint run foo/foo.go:3:1: don't use `init` function (gochecknoinits) func i...

   GOLANG,INIT(),SYNC.ONCE,PANIC     2024-05-10 07:46:18

  var in JavaScript

Geoff published an article sometime ago--"How one missing var ruined our launch". This article described one case where MelonCard uses Node.js as their backend system, suddenly there was a small registration peak period--50-100 people registered concurrently, then the entire website stopped responding and many other strange problems showed up. When they were investigating the source of the problem, they found one missing var in the following code.app.all(‘/apps/:user_id/status’, fun...

   JavaScript,Scope,variable     2012-05-26 12:35:36

  Python Patterns - An Optimization Anecdote

The other day, a friend asked me a seemingly simple question: what's the best way to convert a list of integers into a string, presuming that the integers are ASCII values. For instance, the list [97, 98, 99] should be converted to the string 'abc'. Let's assume we want to write a function to do this. The first version I came up with was totally straightforward: def f1(list): string = "" for item in list: string = string + chr(item) return string ...

   Python,Optimization,Anecdote,Loopup,ASCII     2011-12-18 10:52:49

  File upload once again

File upload is one of the oldest operation of web design. After 20 years, it's still has no big change, difficult to handle, lack of interaction and poor user experience. Web developers have thought many methods to improve the experience of uploading file in web apps, they developed various plugins based on different JavaScript libraries. However, because of the difference among different web browsers, there is no common interface which makes these plugins work properly or easily on all web brow...

   Web design, File upload, Asynchronous,HTML5     2012-09-02 11:52:21

  How does GoLang know how many CPUs to use?

When running lscpu command on Linux, it will list the CPU info on the machine. Take one example where there is one CPU with 2 cores and each core has two threads which indicates there are 4 cores available. Now let's see how many cores GoLang program would identify. From output, NumCPU and GOMAXPROCS both output 4 which is expected. How does go runtime get this info, does it get it through similar command like lscpu or /proc/cpuinfo? Let's dig more in GoLang's source code. In runtim...

   GOLANG,CPU,NCPU     2020-12-29 23:22:15

  What is the use of empty struct in GoLang

In Go, an empty struct struct{} is a struct with no fields that may appear to be of little use, but in reality, it can be useful in certain situations and become a simple and efficient solution in code. As a semaphore or lock Because the empty struct has no fields, it can be conveniently used to implement some concurrency control functions, such as mutex locks, read-write locks. We can use chan struct{} to implement an unbuffered channel for controlling concurrent access. package main import ( ...

   GOLANG,EMPTY STRUCT     2024-04-05 23:54:03

  A trick of building multithreaded application on Solaris

Firstly, Let’s see a simple multithreaded application: #include <stdio.h> #include <pthread.h> #include <errno.h> void *thread1_func(void *p_arg) { errno = 0; sleep(3); errno = 1; printf("%s exit, errno is %d\n", (char*)p_arg, errno); } void *thread2_func(void *p_arg) { errno = 0; sleep(5); printf("%s exit, errno is %d\n", (char*)p_arg, errno); } int main(void) { pthread_t t1, t2; ...

   C, Solaris     2014-10-14 02:59:40

  Let browser prompt for storing password when doing AJAX login

In Web 2.0 era, more and more web applications are using AJAX to replace the traditional HTML form element to perform user login. This usually provides a better user experience than form submission. But it also brings a side effect to the end users. That is the browser will not prompt the user whether s/he wants to save the password so that s/he no needs to enter the username/password again when visiting the same site next time. Below is the code snippet which does the AJAX login.  <scri...

   AJAX,Browser,Login,Password     2015-06-04 10:02:46

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