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Thread Pools

Thread pools on the JVM should usually be divided into the following three categories:

1. CPU-bound
2. Blocking IO
3. Non-blocking IO polling

Each of these categories has a different optimal configuration and usage pattern.

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Count empty values in csv file, grouped by column with pandas

Reference: Data Cleaning with Python and Pandas: Detecting Missing Values

Prerequisites

• Python 3.6
• pip

Running

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import scala.collection._
import com.twitter.util._

scala> val buffer = mutable.ArrayBuffer.empty[Int]
scala> println(Time.measure { (0 to 50000000).foreach { buffer += _ } }.inMillis)
17610

scala> var vector = immutable.Vector.empty[Int]
scala> println(Time.measure { (0 to 50000000).foreach { vector :+= _ } }.inMillis)
7865

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Applied Functional Programming with Scala - Notes

Copyright © 2016-2018 Fantasyland Institute of Learning. All rights reserved.

1. Mastering Functions

A function is a mapping from one set, called a domain, to another set, called the codomain. A function associates every element in the domain with exactly one element in the codomain. In Scala, both domain and codomain are types.

val square : Int => Int = x => x * x

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#!/usr/bin/env bash

# lists all unused AWS security groups.
# a group is considered unused if it's not attached to any network interface.
# requires aws-cli and jq.

# all groups
aws ec2 describe-security-groups \
  | jq --raw-output '.SecurityGroups[] | [.GroupName, .GroupId] | @tsv' \
  | sort > /tmp/sg.all

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public class Constants {

    /**
     * Contains the path to your Lambda function code.
     */
    public static final String LAMBDA_TASK_ROOT = System.getenv("LAMBDA_TASK_ROOT");

    /**
     * The environment variable is set to one of the following options, depending on the runtime of the Lambda function:
     * AWS_Lambda_nodejs, AWS_Lambda_nodejs4.3, AWS_Lambda_nodejs6.10

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akka-persistenceのプラグインをつくろう

• 僕はおくみん
• @okumin

参考

• Persistence — Akka Documentation

Akka persistence is 何

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// Use Gists to store code you would like to remember later on
console.log(window); // log the "window" object to the console

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import scala.slick.lifted.CanBeQueryCondition
// optionally filter on a column with a supplied predicate
case class MaybeFilter[X, Y](val query: scala.slick.lifted.Query[X, Y]) {
  def filter[T,R:CanBeQueryCondition](data: Option[T])(f: T => X => R) = {
    data.map(v => MaybeFilter(query.filter(f(v)))).getOrElse(this)
  }
}

// example use case
import java.sql.Date

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// get handle to build output
def config = new HashMap()
def bindings = getBinding()
config.putAll(bindings.getVariables())
def out = config['out']

for (aSlave in hudson.model.Hudson.instance.slaves) {
  // check if executor is dead
  execList = aSlave.getComputer().getExecutors()      
  for( exec in execList ) {