Adam Daniels

Adam Daniels

1597203778

When and How to use MultiProcessing and Multi-Threading in Python

In this article, you will learn

  • Difference between Multi-Threading and MultiProcessing and when to use them
  • Implement MultiProcessing in Python using multiprocessing and concurrent.futures

What is MultiProcessing?

  • Multiprocessing allows you to spawn multiple processes within a program.
  • It allows you to leverage multiple CPU cores on your machine
  • Multiple processes within a program do not share the memory
  • Side steps the GIL(Global Interpreter Lock) limitation of Python which allows only one thread to hold control of the Python interpreter
  • Used for computation or CPU intensive programs

then what is Multi-threading and when to use it?

A Thread is the

  • Smallest set of independent commands executed in a program
  • Multiple threads within an application can execute simultaneously on a CPU referred to as MultiThreading
  • Runs always within a program and cannot run on its own
  • Used when programs ar network bound or there is heavy I/O operation
  • Memory is shared between multiple threads within a process and hence has lower resources consumption

Image for post

Below is the code to demonstrate that Multiprocessing does not share a memory, whereas Multi-Threading shares memory.

In the piece of code below, we check if the number passed in the list is a prime number or not. We will do this using both Multi-threading as well as using Multiprocessing

#python #developer

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When and How to use MultiProcessing and Multi-Threading in Python

Pyringe: Debugger Capable Of Attaching to & Injecting Code Into Python

DISCLAIMER: This is not an official google project, this is just something I wrote while at Google.

Pyringe

What this is

Pyringe is a python debugger capable of attaching to running processes, inspecting their state and even of injecting python code into them while they're running. With pyringe, you can list threads, get tracebacks, inspect locals/globals/builtins of running functions, all without having to prepare your program for it.

What this is not

A "Google project". It's my internship project that got open-sourced. Sorry for the confusion.

What do I need?

Pyringe internally uses gdb to do a lot of its heavy lifting, so you will need a fairly recent build of gdb (version 7.4 onwards, and only if gdb was configured with --with-python). You will also need the symbols for whatever build of python you're running.
On Fedora, the package you're looking for is python-debuginfo, on Debian it's called python2.7-dbg (adjust according to version). Arch Linux users: see issue #5, Ubuntu users can only debug the python-dbg binary (see issue #19).
Having Colorama will get you output in boldface, but it's optional.

How do I get it?

Get it from the Github repo, PyPI, or via pip (pip install pyringe).

Is this Python3-friendly?

Short answer: No, sorry. Long answer:
There's three potentially different versions of python in play here:

  1. The version running pyringe
  2. The version being debugged
  3. The version of libpythonXX.so your build of gdb was linked against

2 Is currently the dealbreaker here. Cpython has changed a bit in the meantime[1], and making all features work while debugging python3 will have to take a back seat for now until the more glaring issues have been taken care of.
As for 1 and 3, the 2to3 tool may be able to handle it automatically. But then, as long as 2 hasn't been taken care of, this isn't really a use case in the first place.

[1] - For example, pendingbusy (which is used for injection) has been renamed to busy and been given a function-local scope, making it harder to interact with via gdb.

Will this work with PyPy?

Unfortunately, no. Since this makes use of some CPython internals and implementation details, only CPython is supported. If you don't know what PyPy or CPython are, you'll probably be fine.

Why not PDB?

PDB is great. Use it where applicable! But sometimes it isn't.
Like when python itself crashes, gets stuck in some C extension, or you want to inspect data without stopping a program. In such cases, PDB (and all other debuggers that run within the interpreter itself) are next to useless, and without pyringe you'd be left with having to debug using print statements. Pyringe is just quite convenient in these cases.

I injected a change to a local var into a function and it's not showing up!

This is a known limitation. Things like inject('var = 2') won't work, but inject('var[1] = 1337') should. This is because most of the time, python internally uses a fast path for looking up local variables that doesn't actually perform the dictionary lookup in locals(). In general, code you inject into processes with pyringe is very different from a normal python function call.

How do I use it?

You can start the debugger by executing python -m pyringe. Alternatively:

import pyringe
pyringe.interact()

If that reminds you of the code module, good; this is intentional.
After starting the debugger, you'll be greeted by what behaves almost like a regular python REPL.
Try the following:

==> pid:[None] #threads:[0] current thread:[None]
>>> help()
Available commands:
 attach: Attach to the process with the given pid.
 bt: Get a backtrace of the current position.
 [...]
==> pid:[None] #threads:[0] current thread:[None]
>>> attach(12679)
==> pid:[12679] #threads:[11] current thread:[140108099462912]
>>> threads()
[140108099462912, 140108107855616, 140108116248323, 140108124641024, 140108133033728, 140108224739072, 140108233131776, 140108141426432, 140108241524480, 140108249917184, 140108269324032]

The IDs you see here correspond to what threading.current_thread().ident would tell you.
All debugger functions are just regular python functions that have been exposed to the REPL, so you can do things like the following.

==> pid:[12679] #threads:[11] current thread:[140108099462912]
>>> for tid in threads():
...   if not tid % 10:
...     thread(tid)
...     bt()
... 
Traceback (most recent call last):
  File "/usr/lib/python2.7/threading.py", line 524, in __bootstrap
    self.__bootstrap_inner()
  File "/usr/lib/python2.7/threading.py", line 551, in __bootstrap_inner
    self.run()
  File "/usr/lib/python2.7/threading.py", line 504, in run
    self.__target(*self.__args, **self.__kwargs)
  File "./test.py", line 46, in Idle
    Thread_2_Func(1)
  File "./test.py", line 40, in Wait
    time.sleep(n)
==> pid:[12679] #threads:[11] current thread:[140108241524480]
>>> 

You can access the inferior's locals and inspect them like so:

==> pid:[12679] #threads:[11] current thread:[140108241524480]
>>> inflocals()
{'a': <proxy of A object at remote 0x1d9b290>, 'LOL': 'success!', 'b': <proxy of B object at remote 0x1d988c0>, 'n': 1}
==> pid:[12679] #threads:[11] current thread:[140108241524480]
>>> p('a')
<proxy of A object at remote 0x1d9b290>
==> pid:[12679] #threads:[11] current thread:[140108241524480]
>>> p('a').attr
'Some_magic_string'
==> pid:[12679] #threads:[11] current thread:[140108241524480]
>>> 

And sure enough, the definition of a's class reads:

class Example(object):
  cl_attr = False
  def __init__(self):
    self.attr = 'Some_magic_string'

There's limits to how far this proxying of objects goes, and everything that isn't trivial data will show up as strings (like '<function at remote 0x1d957d0>').
You can inject python code into running programs. Of course, there are caveats but... see for yourself:

==> pid:[12679] #threads:[11] current thread:[140108241524480]
>>> inject('import threading')
==> pid:[12679] #threads:[11] current thread:[140108241524480]
>>> inject('print threading.current_thread().ident')
==> pid:[12679] #threads:[11] current thread:[140108241524480]
>>> 

The output of my program in this case reads:

140108241524480

If you need additional pointers, just try using python's help (pyhelp() in the debugger) on debugger commands.

Author: google
Source Code: https://github.com/google/pyringe
License: Apache-2.0 License

#python 

Ray  Patel

Ray Patel

1619510796

Lambda, Map, Filter functions in python

Welcome to my Blog, In this article, we will learn python lambda function, Map function, and filter function.

Lambda function in python: Lambda is a one line anonymous function and lambda takes any number of arguments but can only have one expression and python lambda syntax is

Syntax: x = lambda arguments : expression

Now i will show you some python lambda function examples:

#python #anonymous function python #filter function in python #lambda #lambda python 3 #map python #python filter #python filter lambda #python lambda #python lambda examples #python map

Shardul Bhatt

Shardul Bhatt

1626775355

Why use Python for Software Development

No programming language is pretty much as diverse as Python. It enables building cutting edge applications effortlessly. Developers are as yet investigating the full capability of end-to-end Python development services in various areas. 

By areas, we mean FinTech, HealthTech, InsureTech, Cybersecurity, and that's just the beginning. These are New Economy areas, and Python has the ability to serve every one of them. The vast majority of them require massive computational abilities. Python's code is dynamic and powerful - equipped for taking care of the heavy traffic and substantial algorithmic capacities. 

Programming advancement is multidimensional today. Endeavor programming requires an intelligent application with AI and ML capacities. Shopper based applications require information examination to convey a superior client experience. Netflix, Trello, and Amazon are genuine instances of such applications. Python assists with building them effortlessly. 

5 Reasons to Utilize Python for Programming Web Apps 

Python can do such numerous things that developers can't discover enough reasons to admire it. Python application development isn't restricted to web and enterprise applications. It is exceptionally adaptable and superb for a wide range of uses.

Robust frameworks 

Python is known for its tools and frameworks. There's a structure for everything. Django is helpful for building web applications, venture applications, logical applications, and mathematical processing. Flask is another web improvement framework with no conditions. 

Web2Py, CherryPy, and Falcon offer incredible capabilities to customize Python development services. A large portion of them are open-source frameworks that allow quick turn of events. 

Simple to read and compose 

Python has an improved sentence structure - one that is like the English language. New engineers for Python can undoubtedly understand where they stand in the development process. The simplicity of composing allows quick application building. 

The motivation behind building Python, as said by its maker Guido Van Rossum, was to empower even beginner engineers to comprehend the programming language. The simple coding likewise permits developers to roll out speedy improvements without getting confused by pointless subtleties. 

Utilized by the best 

Alright - Python isn't simply one more programming language. It should have something, which is the reason the business giants use it. Furthermore, that too for different purposes. Developers at Google use Python to assemble framework organization systems, parallel information pusher, code audit, testing and QA, and substantially more. Netflix utilizes Python web development services for its recommendation algorithm and media player. 

Massive community support 

Python has a steadily developing community that offers enormous help. From amateurs to specialists, there's everybody. There are a lot of instructional exercises, documentation, and guides accessible for Python web development solutions. 

Today, numerous universities start with Python, adding to the quantity of individuals in the community. Frequently, Python designers team up on various tasks and help each other with algorithmic, utilitarian, and application critical thinking. 

Progressive applications 

Python is the greatest supporter of data science, Machine Learning, and Artificial Intelligence at any enterprise software development company. Its utilization cases in cutting edge applications are the most compelling motivation for its prosperity. Python is the second most well known tool after R for data analytics.

The simplicity of getting sorted out, overseeing, and visualizing information through unique libraries makes it ideal for data based applications. TensorFlow for neural networks and OpenCV for computer vision are two of Python's most well known use cases for Machine learning applications.

Summary

Thinking about the advances in programming and innovation, Python is a YES for an assorted scope of utilizations. Game development, web application development services, GUI advancement, ML and AI improvement, Enterprise and customer applications - every one of them uses Python to its full potential. 

The disadvantages of Python web improvement arrangements are regularly disregarded by developers and organizations because of the advantages it gives. They focus on quality over speed and performance over blunders. That is the reason it's a good idea to utilize Python for building the applications of the future.

#python development services #python development company #python app development #python development #python in web development #python software development

How To Compare Tesla and Ford Company By Using Magic Methods in Python

Magic Methods are the special methods which gives us the ability to access built in syntactical features such as ‘<’, ‘>’, ‘==’, ‘+’ etc…

You must have worked with such methods without knowing them to be as magic methods. Magic methods can be identified with their names which start with __ and ends with __ like init, call, str etc. These methods are also called Dunder Methods, because of their name starting and ending with Double Underscore (Dunder).

Now there are a number of such special methods, which you might have come across too, in Python. We will just be taking an example of a few of them to understand how they work and how we can use them.

1. init

class AnyClass:
    def __init__():
        print("Init called on its own")
obj = AnyClass()

The first example is _init, _and as the name suggests, it is used for initializing objects. Init method is called on its own, ie. whenever an object is created for the class, the init method is called on its own.

The output of the above code will be given below. Note how we did not call the init method and it got invoked as we created an object for class AnyClass.

Init called on its own

2. add

Let’s move to some other example, add gives us the ability to access the built in syntax feature of the character +. Let’s see how,

class AnyClass:
    def __init__(self, var):
        self.some_var = var
    def __add__(self, other_obj):
        print("Calling the add method")
        return self.some_var + other_obj.some_var
obj1 = AnyClass(5)
obj2 = AnyClass(6)
obj1 + obj2

#python3 #python #python-programming #python-web-development #python-tutorials #python-top-story #python-tips #learn-python

Art  Lind

Art Lind

1602968400

Python Tricks Every Developer Should Know

Python is awesome, it’s one of the easiest languages with simple and intuitive syntax but wait, have you ever thought that there might ways to write your python code simpler?

In this tutorial, you’re going to learn a variety of Python tricks that you can use to write your Python code in a more readable and efficient way like a pro.

Let’s get started

Swapping value in Python

Instead of creating a temporary variable to hold the value of the one while swapping, you can do this instead

>>> FirstName = "kalebu"
>>> LastName = "Jordan"
>>> FirstName, LastName = LastName, FirstName 
>>> print(FirstName, LastName)
('Jordan', 'kalebu')

#python #python-programming #python3 #python-tutorials #learn-python #python-tips #python-skills #python-development