hellerbarde

Latency numbers every programmer should know

L1 cache reference ......................... 0.5 ns
Branch mispredict ............................ 5 ns
L2 cache reference ........................... 7 ns
Mutex lock/unlock ........................... 25 ns
Main memory reference ...................... 100 ns             
Compress 1K bytes with Zippy ............. 3,000 ns  =   3 µs
Send 2K bytes over 1 Gbps network ....... 20,000 ns  =  20 µs
SSD random read ........................ 150,000 ns  = 150 µs

Read 1 MB sequentially from memory ..... 250,000 ns = 250 µs

jboner

Latency Comparison Numbers (~2012)
----------------------------------
L1 cache reference                           0.5 ns
Branch mispredict                            5   ns
L2 cache reference                           7   ns                      14x L1 cache
Mutex lock/unlock                           25   ns
Main memory reference                      100   ns                      20x L2 cache, 200x L1 cache
Compress 1K bytes with Zippy             3,000   ns        3 us
Send 1K bytes over 1 Gbps network       10,000   ns       10 us
Read 4K randomly from SSD*             150,000   ns      150 us          ~1GB/sec SSD

viktorklang

/*
Copyright 2012-2021 Viktor Klang
 
   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at
 
       http://www.apache.org/licenses/LICENSE-2.0
 
   Unless required by applicable law or agreed to in writing, software

kdonald

// convenient Spring JDBC RowMapper for when you want the flexibility of Jackson's TreeModel API
// Note: Jackson can also serialize standard Java Collections (Maps and Lists) to JSON: if you don't need JsonNode,
//   it's simpler and more portable to have Spring JDBC simply return a Map or List<Map>.

package org.springframework.jdbc.core;

import java.math.BigDecimal;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;

cgopalan

object FirstClassFunctions {
  def sum(f: Int => Int)(a: Int, b:Int): Int = {
    def iter(a: Int, result: Int): Int =
      if (a > b) result
      else iter(a + 1, f(a) + result)
    iter(a,0)
  }
  
  def main(args: Array[String]) {
    println("Sum is: " + sum(x => x)(1,10))

QuerydslBeanProjection.java

QEmployee qEmployee = QEmployee.employee;
List<Employee> emps = sqlQuery.from(qEmployee)
  .where(qEmployee.name.eq(name))
  .list(new QBean<Employee>(Employee.class, qEmployee.id, qEmployee.name));

// QBean defines a Bean populating projection, the first argument is the Bean class and the rest the paths to be used for Bean population