pingrunhuang

• ThreadPoolExecutor is good for when you don't want to re-create threads over and over again. Better if you have a looping task that needs to be ran in a sub threads
• Threading & queue is good for simplicity that you have a one off task

pingrunhuang

# yield 和 join 使用
### yield方法
暂停当前正在执行的线程对象。
yield()方法是停止当前线程，让同等优先权的线程或更高优先级的线程有执行的机会。  
如果没有的话，那么yield()方法将不会起作用，并且由可执行状态后马上又被执行。

### join是Thread方法 
join方法适用于在某一个线程的执行过程中调用另一个线程执行，等到被调用的线程执行结束后，再继续执行当前线程。如：t.join();  
主要用于等待t线程运行结束，若无此句，main则会执行完毕，导致结果不可预测。

pingrunhuang

abstract class Monoid[A] {
  def add(x: A, y: A): A
  def unit: A
}

object ImplicitTest {
  implicit val stringMonoid: Monoid[String] = new Monoid[String] {
    def add(x: String, y: String): String = x concat y
    def unit: String = ""
  }

pingrunhuang

"""
Note from https://jeffknupp.com/blog/2016/03/07/python-with-context-managers/
"""
# first way of creating a context manager
class File():
  
  def __init__(self, filename, mode):
    self.filename=filename
    self.mode=mode
  

pingrunhuang

One-line Tree in Python

Using Python's built-in defaultdict we can easily define a tree data structure:

def tree(): return defaultdict(tree)

That's it!

pingrunhuang

class Count(object):
    def __init__(self, start=0, step=1, stop=10):
        self.n = start
        self.step = step
        self.stop = stop

    def __next__(self):
        n = self.n
        if n>self.stop:
            raise StopIteration()

pingrunhuang

SELECT "运单号", "sum"("开单金额"), "收货本部"
FROM express_2016_01 
GROUP BY "运单号", "收货本部" 
ORDER BY "sum"("开单金额") DESC
LIMIT 10

pingrunhuang

RUN curl -LO 'http://download.oracle.com/otn-pub/java/jdk/7u71-b14/jdk-7u71-linux-x64.rpm' -H 'Cookie: oraclelicense=accept-securebackup-cookie'
RUN rpm -i jdk-7u71-linux-x64.rpm
RUN rm jdk-7u71-linux-x64.rpm

ENV JAVA_HOME /usr/java/default
ENV PATH $PATH:$JAVA_HOME/bin
RUN rm /usr/bin/java && ln -s $JAVA_HOME/bin/java /usr/bin/java

pingrunhuang

package main

import "fmt"

// channel as argument
func sum(s []int, c chan int) {
	sum := 0
	for _, v := range s {
		sum += v
	}

pingrunhuang

import logging
import threading
import time

logging.basicConfig(level=logging.DEBUG,
                    format='[%(levelname)s] (%(threadName)-10s) %(message)s',
                    )

def worker():
    logging.debug('Starting')