multithreading - creating threads
Python MultithreadCreating a thread and passing arguments to the thread
Identifying threads - naming and logging
Daemon thread & join() method
Active threads & enumerate() method
Subclassing & overriding run() and __init__() methods
Event objects - set() & wait() methods
Lock objects - acquire() & release() methods
RLock (Reentrant) objects - acquire() method
Using locks in the with statement - context manager
Condition objects with producer and consumer
Producer and Consumer with Queue
Semaphore objects & thread pool
Thread specific data - threading.local()
Using threads allows a program to run multiple operations concurrently in the same process space. Through out this tutorials, we'll be using threading module. Note that there is another module called thread which has been renamed to _thread in Python 3. Actually, the threading module constructs higher-level threading interfaces on top of the lower level _thread module. We rarely touch the low level _thread module.
The Thread class is defined in http://hg.python.org/cpython/file/3.4/Lib/threading.py.
The __init__() of the Thread class looks like this:
def __init__(self, group=None, target=None, name=None, args=(), kwargs=None, *, daemon=None):
In this section, we'll start with the simplest way to use a Thread. So, as shown in the code below, we instantiate it with a target function f() and call start() to let it begin working. The target is the callable object to be invoked by the run() method. Defaults to None, meaning nothing is called.
import threading def f(): print 'thread function' return if __name__ == '__main__': for i in range(3): t = threading.Thread(target=f) t.start()
The start() starts the thread's activity. It must be called at most once per thread object. It arranges for the object's run() method to be invoked in a separate thread of control.
This method will raise a RuntimeError if called more than once on the same thread object.
The code will output "thread function" three times:
thread function thread function thread function
The run() method is called by start() method (check threading.py):
class Thread: ... def start(self): """Start the thread's activity. It must be called at most once per thread object. It arranges for the object's run() method to be invoked in a separate thread of control. This method will raise a RuntimeError if called more than once on the same thread object. """ if not self._initialized: raise RuntimeError("thread.__init__() not called") if self._started.is_set(): raise RuntimeError("threads can only be started once") with _active_limbo_lock: _limbo[self] = self try: _start_new_thread(self._bootstrap, ()) except Exception: with _active_limbo_lock: del _limbo[self] raise self._started.wait() def _bootstrap(self): try: self._bootstrap_inner() except: if self._daemonic and _sys is None: return raise def _bootstrap_inner(self): try: ... try: self.run() except SystemExit: pass except:
To make a thread more useful, we want to pass args to give more information about the work. The code below passes an integer for thread id, and then the thread prints it. The args is the argument tuple for the target invocation. Defaults to ().
import threading def f(id): print 'thread function %s' %(id) return if __name__ == '__main__': for i in range(3): t = threading.Thread(target=f, args=(i,)) t.start()
thread function 0 thread function 1 thread function 2
Now the integer argument is included in the message printed by each thread.
Running Python Programs (os, sys, import)
Modules and IDLE (Import, Reload, exec)
Object Types - Numbers, Strings, and None
Strings - Escape Sequence, Raw String, and Slicing
Strings - Methods
Formatting Strings - expressions and method calls
Files and os.path
Traversing directories recursively
Regular Expressions with Python
Object Types - Lists
Object Types - Dictionaries and Tuples
Functions def, *args, **kargs
map, filter, and reduce
Sets (union/intersection) and itertools - Jaccard coefficient and shingling to check plagiarism
Hashing (Hash tables and hashlib)
Dictionary Comprehension with zip
The yield keyword
Generator Functions and Expressions
Classes and Instances (__init__, __call__, etc.)
if__name__ == '__main__'
@static method vs class method
Private attributes and private methods
bits, bytes, bitstring, and constBitStream
json.dump(s) and json.load(s)
Python Object Serialization - pickle and json
Python Object Serialization - yaml and json
Priority queue and heap queue data structure
Graph data structure
Dijkstra's shortest path algorithm
Prim's spanning tree algorithm
Functional programming in Python
Remote running a local file using ssh
SQLite 3 - A. Connecting to DB, create/drop table, and insert data into a table
SQLite 3 - B. Selecting, updating and deleting data
MongoDB with PyMongo I - Installing MongoDB ...
Python HTTP Web Services - urllib, httplib2
Web scraping with Selenium for checking domain availability
REST API : Http Requests for Humans with Flask
Blog app with Tornado
Python Network Programming I - Basic Server / Client : A Basics
Python Network Programming I - Basic Server / Client : B File Transfer
Python Network Programming II - Chat Server / Client
Python Network Programming III - Echo Server using socketserver network framework
Python Network Programming IV - Asynchronous Request Handling : ThreadingMixIn and ForkingMixIn
Python Interview Questions I
Python Interview Questions II
Python Interview Questions III
Python Interview Questions IV
Image processing with Python image library Pillow
Python and C++ with SIP
PyDev with Eclipse
Redis with Python
NumPy array basics A
NumPy Matrix and Linear Algebra
Pandas with NumPy and Matplotlib
Batch gradient descent algorithm
Longest Common Substring Algorithm
Python Unit Test - TDD using unittest.TestCase class
Simple tool - Google page ranking by keywords
Google App Hello World
Google App webapp2 and WSGI
Uploading Google App Hello World
Python 2 vs Python 3
virtualenv and virtualenvwrapper
Uploading a big file to AWS S3 using boto module
Scheduled stopping and starting an AWS instance
Cloudera CDH5 - Scheduled stopping and starting services
Removing Cloud Files - Rackspace API with curl and subprocess
Checking if a process is running/hanging and stop/run a scheduled task on Windows
Apache Spark 1.3 with PySpark (Spark Python API) Shell
Apache Spark 1.2 Streaming
bottle 0.12.7 - Fast and simple WSGI-micro framework for small web-applications ...
Flask app with Apache WSGI on Ubuntu14/CentOS7 ...
Fabric - streamlining the use of SSH for application deployment
Ansible Quick Preview - Setting up web servers with Nginx, configure enviroments, and deploy an App
Neural Networks with backpropagation for XOR using one hidden layer
NLP - NLTK (Natural Language Toolkit) ...
RabbitMQ(Message broker server) and Celery(Task queue) ...
OpenCV3 and Matplotlib ...
Simple tool - Concatenating slides using FFmpeg ...
iPython - Signal Processing with NumPy
iPython and Jupyter - Install Jupyter, iPython Notebook, drawing with Matplotlib, and publishing it to Github
iPython and Jupyter Notebook with Embedded D3.js
Downloading YouTube videos using youtube-dl embedded with Python
Machine Learning : scikit-learn ...
Django 1.6/1.8 Web Framework ...
Ph.D. / Golden Gate Ave, San Francisco / Seoul National Univ / Carnegie Mellon / UC Berkeley / DevOps / Deep Learning / Visualization