Threading in Python

Very very similar to Java but with less code. 

import threading

import datetime

import time

DELAY = 10

def hacertrabajo():

timeinit = datetime.datetime.now()

print("se inicia "+str(timeinit))

time.sleep(10)

print("se finaliza "+ str(datetime.datetime.now()) + "en "+str(datetime.datetime.now()-timeinit))

th1 = threading.Thread(target=hacertrabajo,name="th-1")

th2 = threading.Thread(target=hacertrabajo,name="th-2")

th1.start()

th2.start()

print("no se espera")

if you execute the prgoram you will see that the output "no se espear" is writtein even without having finisthed both threads.

PS C:\Users\jordi\Documents\python\multithread> python multi.py
se inicia 2018-02-26 22:02:26.326352
start th1
se inicia 2018-02-26 22:02:26.328306
start th2
no se espera
se finaliza 2018-02-26 22:02:36.328301en 0:00:10.001949
se finaliza 2018-02-26 22:02:36.330257en 0:00:10.001951

to wait implement the call join(seconds) where seconds are the timeout , the time point the time when the control will arive to point join

import threading

import datetime

import time

DELAY = 10

def hacertrabajo():

timeinit = datetime.datetime.now()

print("se inicia "+str(timeinit))

time.sleep(10)

print("se finaliza "+ str(datetime.datetime.now()) + "en "+str(datetime.datetime.now()-timeinit))

th1 = threading.Thread(target=hacertrabajo,name="th-1")

th2 = threading.Thread(target=hacertrabajo,name="th-2")

th1.start()

th2.start()

timeinit = datetime.datetime.now()

th1.join(5)

print("se finaliza th1 "+ str(datetime.datetime.now()) + "en "+str(datetime.datetime.now()-timeinit))

th2.join(11)

print("se finaliza th2"+ str(datetime.datetime.now()) + "en "+str(datetime.datetime.now()-timeinit))

Da el resultado siguiente.

PS C:\Users\jordi\Documents\python\multithread> python multi.py
se inicia 2018-02-26 22:22:31.651966
se inicia 2018-02-26 22:22:31.652945
se finaliza th1 2018-02-26 22:22:36.653236en 0:00:05.000291
se finaliza 2018-02-26 22:22:41.653288en 0:00:10.001322
se finaliza 2018-02-26 22:22:41.654265en 0:00:10.001320
se finaliza th22018-02-26 22:22:41.655247en 0:00:10.002302
PS C:\Users\jordi\Documents\python\multithread>

Tal y como indica la documentacion lo normal de join() seria despues hacer algo con el thread como

PlyGround with Python 1

how easy is python and sqlite3

import sqlite3

import datetime

def createDataBase():

conn = sqlite3.connect('control.db')

c = conn.cursor()

c.execute('create table control( nombre TEXT, fechaini timestamp, fechafin timestamp)')

c.close()

def pupulateDataBase():

conn = sqlite3.connect('control.db')

c = conn.cursor()

c.execute('insert into control values (?,?,?)',('registro 1',datetime.datetime.now(),datetime.datetime.now()))

conn.commit()

conn.close()

def pupulateDataBaseWhitNull():

conn = sqlite3.connect('control.db')

c = conn.cursor()

c.execute('insert into control values (?,?,?)',('registro 1',datetime.datetime.now(),None))

conn.commit()

conn.close()

def fetchDataBase():

conn = sqlite3.connect('control.db')

c = conn.cursor()

for row in c.execute('SELECT * FROM control'):

print(row)

createDataBase()

pupulateDataBase()

pupulateDataBaseWhitNull()

fetchDataBase()

(test) C:\Users\jordi\jordi\workspaces\python\test>python testsqlite.py
('registro 1', '2018-02-17 10:48:47.235088', '2018-02-17 10:48:47.235088')
('registro 1', '2018-02-17 10:48:47.354523', None)

LightWeight Python Envirotment with Visual Studio 

Create a virtualenv with virtualenv and later activate it running the activate script.

Open the VSC and creaate a fill called .env with the variable PYTHONPATH pointing to the site-packages where the virualenv located all the libraries already download by PIP.

PYTHONPATH=C:\Users\jordi\jordi\workspaces\python\test\Lib\site-packages

Little’s law

number of threads = (Requests/sec) X (ResponseTime in secs)

ssh keys

From my laptop I will create the keys and I will expose this key to the server I want to connect using keys. Additionally we get rid of passwords , even for my user as sudo user.

jordi@LAPTOP-ELFAQNCG MINGW64 ~/.ssh

$ ssh-keygen -t rsa

Generating public/private rsa key pair.

Enter file in which to save the key (/c/Users/jordi/.ssh/id_rsa):

Enter passphrase (empty for no passphrase):

Enter same passphrase again:

Your identification has been saved in /c/Users/jordi/.ssh/id_rsa.

Your public key has been saved in /c/Users/jordi/.ssh/id_rsa.pub.

The key fingerprint is:

SHA256:ljvEge2a/MwKp8OK73ai27v7zRFiPyPmMxJCpw0nJLU jordi@LAPTOP-ELFAQNCG

The key's randomart image is:

+---[RSA 2048]----+

| ..              |

|.. .   o         |

|o E   . o        |

| + o   o o       |

|. B o . S        |

|...o + * .       |

| . o+ X o        |

| o+o*B B .       |

|+*OX+++.+        |

+----[SHA256]-----+

jordi@LAPTOP-ELFAQNCG MINGW64 ~/.ssh

$ ssh-copy-id jordi@localhost

/usr/bin/ssh-copy-id: INFO: Source of key(s) to be installed: "/c/Users/jordi/.ssh/id_rsa.pub"

/usr/bin/ssh-copy-id: INFO: attempting to log in with the new key(s), to filter out any that are already installed

/usr/bin/ssh-copy-id: INFO: 1 key(s) remain to be installed -- if you are prompted now it is to install the new keys

no such identity: /c/Users/jordi/.ssh/keys/id_rsa.pub: No such file or directory

jordi@localhost's password:

Number of key(s) added: 1

Now try logging into the machine, with:   "ssh 'jordi@localhost'"

and check to make sure that only the key(s) you wanted were added

jordi@LAPTOP-ELFAQNCG MINGW64 ~/.ssh

$ cat config

Host localhost

 Hostname localhost

 IdentityFile ~/.ssh/id_rsa

.

jordi@LAPTOP-ELFAQNCG MINGW64 ~/.ssh

$ ssh localhost

Last login: Sat Feb  3 17:27:47 2018 from gateway

[jordi@localhost ~]$

At centos to avoid password for instance to avoid pas to do sudo

/etc/ssh/sshd_config

PasswordAuthentication no

addl to the bototn

 sudo visudo

jordi ALL=(ALL) NOPASSWD: ALL