Python Threading

https://superfastpython.com/threading-in-python/
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### Complete Example: Extending Thread Class in Python

Source: https://superfastpython.com/threading-in-python/index

This is a complete example demonstrating how to extend the `threading.Thread` class in Python. It includes defining a custom thread, overriding `run()`, starting the thread, and waiting for it to finish.

```python
# SuperFastPython.com
# example of extending the Thread class
from time import sleep
from threading import Thread

# custom thread class
class CustomThread(Thread):
    # override the run function
    def run(self):
        # block for a moment
        sleep(1)
        # display a message
        print('This is coming from another thread')

# create the thread
thread = CustomThread()

# start the thread
thread.start()

# wait for the thread to finish
print('Waiting for the thread to finish')
thread.join()

```

--------------------------------

### Python Livelock Demonstration with Threads and Locks

Source: https://superfastpython.com/threading-in-python/index

Sets up and runs a Python livelock example. It creates two mutex locks and two threads, each executing the 'task' function with the locks provided in a different order to induce a livelock. The main thread then starts the worker threads and waits for them to complete.

```python
from threading import Thread, Lock
from time import sleep

def task(number, lock1, lock2):
    while True:
        with lock1:
            sleep(0.1)
            if lock2.locked():
                print(f'Task {number} cannot get the second lock, giving up...')
            else:
                with lock2:
                    print(f'Task {number} made it, all done.')
                    break

# create locks
lock1 = Lock()
lock2 = Lock()

# create threads
thread1 = Thread(target=task, args=(0, lock1, lock2))
thread2 = Thread(target=task, args=(1, lock2, lock1))

# start threads
thread1.start()
thread2.start()

# wait for threads to finish
thread1.join()
thread2.join()
```

--------------------------------

### Complete Python Example: Wait and Notify with Condition

Source: https://superfastpython.com/threading-in-python/index

A full example demonstrating inter-thread communication using threading.Condition. It includes the worker thread's task function and the main thread's logic for creating, starting, waiting, and finally processing data. This example highlights the importance of acquiring the condition's lock before starting the worker thread to prevent race conditions.

```python
# SuperFastPython.com
# example of wait/notify with a condition
from time import sleep
from threading import Thread
from threading import Condition

# target function to prepare some work
def task(condition, work_list):
    # block for a moment
    sleep(1)
    # add data to the work list
    work_list.append(33)
    # notify a waiting thread that the work is done
    print('Thread sending notification...')
    with condition:
        condition.notify()

# create a condition
condition = Condition()
# prepare the work list
work_list = list()

# wait to be notified that the data is ready
print('Main thread waiting for data...')
with condition:
    # start a new thread to perform some work
    worker = Thread(target=task, args=(condition, work_list))
    worker.start()
    # wait to be notified
    condition.wait()

# we know the data is ready
print(f'Got data: {work_list}')
```

--------------------------------

### Complete Example: Stopping a Thread Gracefully in Python

Source: https://superfastpython.com/threading-in-python/index

A comprehensive example demonstrating how to create a thread, run a task within it that checks for a stop signal (threading.Event), and how the main thread signals and waits for the worker thread to terminate.

```python
# SuperFastPython.com
# example of stopping a new thread
from time import sleep
from threading import Thread
from threading import Event

# custom task function
def task(event):
    # execute a task in a loop
    for i in range(5):
        # block for a moment
        sleep(1)
        # check for stop
        if event.is_set():
            break
        # report a message
        print('Worker thread running...')
    print('Worker closing down')

# create the event
event = Event()

# create and configure a new thread
thread = Thread(target=task, args=(event,))

# start the new thread
thread.start()

# block for a while
sleep(3)

# stop the worker thread
print('Main stopping thread')
event.set()

# wait for the new thread to finish
thread.join()
```

--------------------------------

### Create and Start a Custom Thread in Python

Source: https://superfastpython.com/threading-in-python/index

This snippet shows how to create an instance of a custom thread class and start its execution using the `start()` method. The `start()` method internally calls the `run()` method in a new thread.

```python
# create the thread
thread = CustomThread()
# start the thread
thread.start()

```

--------------------------------

### Get Main Thread Instance using main_thread() in Python

Source: https://superfastpython.com/threading-in-python/index

Shows how to retrieve a threading.Thread instance for the main thread from any thread using the threading.main_thread() function. The example reports the name, daemon status, and identifier of the main thread.

```python
# SuperFastPython.com
# example of getting the main thread
from threading import main_thread

# get the main thread
thread = main_thread()

# report properties for the main thread
print(f'name={thread.name}, daemon={thread.daemon}, id={thread.ident}')

```

--------------------------------

### Configure Daemon Thread via Property in Python

Source: https://superfastpython.com/threading-in-python/index

This example shows how to create a standard threading.Thread instance and then configure it to be a daemon thread by setting its 'daemon' property to True after instantiation. Finally, it prints the daemon status.

```python
# SuperFastPython.com
# example of setting a thread to be a daemon via the property
from threading import Thread

# create a thread
thread = Thread()

# configure the thread to be a daemon
thread.daemon = True

# report if the thread is a daemon
print(thread.daemon)
```

--------------------------------

### Attempt to Restart a Terminated Thread in Python

Source: https://superfastpython.com/threading-in-python/index

Illustrates the behavior when attempting to restart a thread after it has terminated. This example shows that calling start() on a terminated thread raises a RuntimeError, as threads can only be started once.

```python
# SuperFastPython.com
# example of reusing a thread
from time import sleep
from threading import Thread

# custom target function
def task():
    # block for a moment
    sleep(1)
    # report a message
    print('Hello from the new thread')

# create a new thread
thread = Thread(target=task)

# start the thread
thread.start()

# wait for the thread to finish
thread.join()

# try and start the thread again
thread.start()
```

--------------------------------

### Run a Function in a New Thread in Python

Source: https://superfastpython.com/threading-in-python/index

Demonstrates how to create and run a simple function in a new thread. It defines a task function, creates a `threading.Thread` instance targeting that function, starts the thread, and then waits for it to complete using `join()`.

```python
# SuperFastPython.com
# example of running a function in another thread
from time import sleep
from threading import Thread

# a custom function that blocks for a moment
def task():
    # block for a moment
    sleep(1)
    # display a message
    print('This is from another thread')

# create a thread
thread = Thread(target=task)

# run the thread
thread.start()

# wait for the thread to finish
print('Waiting for the thread...')
thread.join()
```

--------------------------------

### Set Thread Name via Constructor (Python)

Source: https://superfastpython.com/threading-in-python/index

Shows how to assign a custom name to a `threading.Thread` instance during its creation using the 'name' argument. The example then prints the assigned name.

```python
# SuperFastPython.com
# example of setting the thread name in the constructor
from threading import Thread

# create a thread with a custom name
thread = Thread(name='MyThread')

# report thread name
print(thread.name)
```

--------------------------------

### Create Daemon Thread via Constructor in Python

Source: https://superfastpython.com/threading-in-python/index

This example demonstrates how to create a new thread and configure it to be a daemon thread directly within the threading.Thread constructor by setting the 'daemon' argument to True. It then prints the daemon status of the thread.

```python
# SuperFastPython.com
# example of setting a thread to be a daemon via the constructor
from threading import Thread

# create a daemon thread
thread = Thread(daemon=True)

# report if the thread is a daemon
print(thread.daemon)
```

--------------------------------

### Get Current Thread Instance using current_thread() in Python

Source: https://superfastpython.com/threading-in-python/index

Demonstrates how to obtain a threading.Thread instance for the currently executing thread using threading.current_thread(). The example defines a task function that reports its own thread's name.

```python
# SuperFastPython.com
# retrieve the current thread within
from threading import Thread
from threading import current_thread

# function to get the current thread
def task():
    # get the current thread
    thread = current_thread()
    # report the name
    print(thread.name)

# create a thread
thread = Thread(target=task)
# start the thread
thread.start()
# wait for the thread to exit
thread.join()

```

--------------------------------

### Get Main Thread Instance using current_thread() in Python

Source: https://superfastpython.com/threading-in-python/index

Demonstrates how to obtain a threading.Thread instance representing the main thread by calling threading.current_thread(). It then reports properties like name, daemon status, and identifier.

```python
# SuperFastPython.com
# example of getting the current thread for the main thread
from threading import current_thread

# get the main thread
thread = current_thread()

# report properties for the main thread
print(f'name={thread.name}, daemon={thread.daemon}, id={thread.ident}')

```

--------------------------------

### Complete Reentrant Lock Example in Python

Source: https://superfastpython.com/threading-in-python/index

A full example showcasing the use of threading.RLock in Python. It defines functions for reporting and task execution, both protected by the same RLock. This demonstrates how a thread holding the lock can re-enter it, preventing deadlocks.

```python
# SuperFastPython.com
# example of a reentrant lock
from time import sleep
from random import random
from threading import Thread
from threading import RLock

# reporting function
def report(lock, identifier):
    # acquire the lock with lock:
    with lock:
        print(f'>thread {identifier} done')

# work function
def task(lock, identifier, value):
    # acquire the lock with lock:
    with lock:
        print(f'>thread {identifier} sleeping for {value}')
        sleep(value)
        # report
        report(lock, identifier)

# create a shared reentrant lock
lock = RLock()

# start a few threads that attempt to execute the same critical section
for i in range(10):
    # start a thread
    Thread(target=task, args=(lock, i, random())).start()

# wait for all threads to finish...
# (In a real application, you'd likely use thread.join() or similar)
```

--------------------------------

### Set Thread Name via Property (Python)

Source: https://superfastpython.com/threading-in-python/index

Demonstrates how to set the name of an existing `threading.Thread` instance by assigning a value to its 'name' property after creation. The example then prints the updated name.

```python
# SuperFastPython.com
# example of setting the thread name via the property
from threading import Thread

# create a thread
thread = Thread()

# set the name
thread.name = 'MyThread'

# report thread name
print(thread.name)
```

--------------------------------

### Python Thread Barrier Example

Source: https://superfastpython.com/threading-in-python/index

Demonstrates using `threading.Barrier` to synchronize multiple worker threads and the main thread. Each thread performs a task, waits at the barrier, and the main thread waits for all workers to complete.

```python
# SuperFastPython.com
# example of using a barrier
from time import sleep
from random import random
from threading import Thread
from threading import Barrier

# target function to prepare some work
def task(barrier, number):
    # generate a unique value
    value = random() * 10
    # block for a moment
    sleep(value)
    # report result
    print(f'Thread {number} done, got: {value}')
    # wait on all other threads to complete
    barrier.wait()

# create a barrier
barrier = Barrier(5 + 1)

# create the worker threads
for i in range(5):
    # start a new thread to perform some work
    worker = Thread(target=task, args=(barrier, i))
    worker.start()

# wait for all threads to finish
print('Main thread waiting on all results...')
barrier.wait()

# report once all threads are done
print('All threads have their result')
```

--------------------------------

### Wait on Barrier in Python

Source: https://superfastpython.com/threading-in-python/index

Provides an example of a thread waiting at the barrier. The wait() function blocks until all specified parties arrive. It returns the number of remaining parties.

```python
# wait on the barrier for all other threads to arrive
barrier.wait()
```

--------------------------------

### Python: Create and Use Semaphore with Threads

Source: https://superfastpython.com/threading-in-python/index

Illustrates the complete example of using a semaphore in Python for thread synchronization. It initializes a semaphore with a limit, creates multiple worker threads that execute a task function, and ensures all threads complete before the main program exits. The semaphore limits concurrent access to the task.

```python
# SuperFastPython.com
# example of using a semaphore
from time import sleep
from random import random
from threading import Thread
from threading import Semaphore

# target function
def task(semaphore, number):
    # attempt to acquire the semaphore
    with semaphore:
        # process
        value = random()
        sleep(value)
        # report result
        print(f'Thread {number} got {value}')

# create a semaphoresemaphore = Semaphore(2)

# create a suite of threads
for i in range(10):
    worker = Thread(target=task, args=(semaphore, i))
    worker.start()

# wait for all workers to complete...

```

--------------------------------

### Schedule Function Execution with threading.Timer in Python

Source: https://superfastpython.com/threading-in-python/index

Illustrates how to use the threading.Timer class to execute a function after a specified delay. The Timer is a subclass of Thread and can be started, and optionally cancelled, before the delay elapses.

```python
# configure a timer thread
timer = Timer(10, task, args=(arg1, arg2))
```

```python
# start the timer thread
timer.start()
```

```python
# cancel the timer thread
timer.cancel()
```

--------------------------------

### Python Blocking Lock Acquisition

Source: https://superfastpython.com/threading-in-python/index

This example shows the standard way to acquire a lock in Python by blocking. The thread will pause execution until the lock becomes available, unlike a spinlock which continuously checks. This is generally preferred to avoid busy-waiting.

```python
# block until the lock can be acquired
lock.acquire()
```

--------------------------------

### Get and Set Python Context Switch Interval

Source: https://superfastpython.com/threading-in-python/index

Demonstrates how to retrieve the current context switch interval and set a new interval in seconds using Python's sys module. This affects how long a Python thread runs before being considered for a context switch.

```python
# Get the current switch interval
interval = sys.getswitchinterval()
print(f"Current switch interval: {interval} seconds")

# Set a new switch interval (e.g., 1.0 second)
sys.setswitchinterval(1.0)
print(f"New switch interval set to: {sys.getswitchinterval()} seconds")
```

--------------------------------

### Handling delays before condition.wait() in Python

Source: https://superfastpython.com/threading-in-python/index

This example demonstrates how a thread can set an event, introduce a delay, and then wait on a condition. Because the condition is acquired before waiting, the main thread cannot call notify() until this thread calls wait(), preventing race conditions.

```python
with condition:
    event.set()
    sleep(5)
    condition.wait()
```

--------------------------------

### Handle Unhandled Exceptions in Python Threads

Source: https://superfastpython.com/threading-in-python/index

Demonstrates how an unhandled exception in a thread unwinds the thread and reports the error to standard error without affecting the main thread. The example defines a target function that raises an exception after a delay, creates a thread to run it, and then joins the thread.

```python
# SuperFastPython.com
# example of an unhandled exception in a thread
from time import sleep
from threading import Thread

# target function that raises an exception
def work():
    print('Working...')
    sleep(1)
    # rise an exception
    raise Exception('Something bad happened')

# create a thread
thread = Thread(target=work)

# run the thread
thread.start()

# wait for the thread to finish
thread.join()

# continue on
print('Continuing on...')
```

--------------------------------

### Get Thread Identifier in Python

Source: https://superfastpython.com/threading-in-python/index

Shows how to access the 'ident' property of a threading.Thread instance to get its unique Python interpreter-assigned identifier. The identifier is assigned after the thread starts.

```python
# SuperFastPython.com
# example of reporting the thread identifier
from threading import Thread

# create the thread
thread = Thread()

# report the thread identifier
print(thread.ident)

# start the thread
thread.start()

# report the thread identifier
print(thread.ident)
```

--------------------------------

### Configure Barrier with Action in Python

Source: https://superfastpython.com/threading-in-python/index

Shows how to configure a barrier to execute a specific action once all threads have arrived. The 'action' argument takes a callable (like a function or lambda) that runs before threads are released.

```python
# configure a barrier with an action
barrier = threading.Barrier(10, action=my_function)
```

--------------------------------

### Get Thread Native Identifier in Python

Source: https://superfastpython.com/threading-in-python/index

Illustrates how to retrieve the 'native_id' property of a threading.Thread instance, which represents the operating system-assigned unique identifier for the thread. This ID is available after the thread has started.

```python
# SuperFastPython.com
# example of reporting the native thread identifier
from threading import Thread

# create the thread
thread = Thread()

# report the native thread identifier
print(thread.native_id)

# start the thread
thread.start()

# report the native thread identifier
print(thread.native_id)
```

--------------------------------

### Using Countdown Latch in Python

Source: https://superfastpython.com/threading-in-python/index

Demonstrates the usage of the CountDownLatch class. It shows how to initialize the latch with a specific count and how to use the count_down() and wait() methods to coordinate threads.

```python
# create the countdown latch
latch = CountDownLatch(5)

# ... other thread operations ...

# As each party arrives at the latch, call count_down()
latch.count_down()

# Any threads interested in when the latch is open can call wait()
latch.wait()
```

--------------------------------

### Get Number of Active Threads using active_count() in Python

Source: https://superfastpython.com/threading-in-python/index

Illustrates how to find the number of currently active (alive) threads in a Python process using the threading.active_count() function. The example prints the integer count returned by the function.

```python
# SuperFastPython.com
# report the number of active threads
from threading import active_count

# get the number of active threads
count = active_count()

# report the number of active threads
print(count)

```

--------------------------------

### Create a Barrier in Python

Source: https://superfastpython.com/threading-in-python/index

Demonstrates the basic creation of a threading.Barrier instance. The barrier is initialized with the number of threads (parties) that must reach it before it can be passed.

```python
# create a barrier
barrier = threading.Barrier(10)
```

--------------------------------

### Python Main Thread Waiting for Condition Notification

Source: https://superfastpython.com/threading-in-python/index

Sets up the main thread to wait for a notification. It initializes a Condition object and a shared list, starts a worker thread, and then waits using condition.wait() until the worker thread signals completion. It requires the Condition and list to be initialized prior to starting the worker thread.

```python
# create a condition
condition = Condition()
# prepare the work list
work_list = list()

# wait to be notified that the data is ready
print('Main thread waiting for data...')
with condition:
    # start a new thread to perform some work
    worker = Thread(target=task, args=(condition, work_list))
    worker.start()
    # wait to be notified
    condition.wait()
```

--------------------------------

### Manual Lock Acquisition and Release in Python

Source: https://superfastpython.com/threading-in-python/index

Demonstrates the traditional method of manually acquiring and releasing a lock using acquire() and release() methods. This approach requires careful management within try-finally blocks to ensure the lock is always released, even if errors occur.

```python
import threading

lock = threading.Lock()

# acquire the lock manually
lock.acquire()

# critical section...

# release the lock
lock.release()
```

--------------------------------

### Get the Name of a Thread in Python

Source: https://superfastpython.com/threading-in-python/index

Shows how to retrieve the name of a thread instance using the 'name' property. Thread names default to 'Thread-N' if not explicitly set.

```python
# report the name of the thread
print(thread.name)
```

--------------------------------

### Create a threading.Event Object in Python

Source: https://superfastpython.com/threading-in-python/index

Demonstrates how to create an instance of the threading.Event object. The event is initially in the 'not set' state (False). This is the first step before any communication can occur.

```python
import threading

# create an instance of an event
event = threading.Event()
```

--------------------------------

### Override the run() Method for Thread Execution in Python

Source: https://superfastpython.com/threading-in-python/index

This snippet demonstrates overriding the `run()` method of a custom thread class. The code within this method will be executed when the thread is started.

```python
# override the run function
def run(self):
    # ...

```

--------------------------------

### Create a Thread with a Custom Name in Python

Source: https://superfastpython.com/threading-in-python/index

Demonstrates how to assign a custom name to a thread during its creation using the 'name' argument in the threading.Thread constructor.

```python
# create with a custom name
thread = Thread(name='MyThread')
```

--------------------------------

### Acquiring Lock with Timeout in Python

Source: https://superfastpython.com/threading-in-python/index

Demonstrates how to acquire a lock with a specified timeout in Python. This prevents threads from blocking indefinitely and allows for handling cases where the lock cannot be acquired within the given time.

```python
import threading

lock = threading.Lock()

# acquire the lock with a timeout of 2 minutes
if not lock.acquire(timeout=2*60):
    # handle failure case, e.g., report error, force termination
```

--------------------------------

### Configure Barrier with Timeout in Python

Source: https://superfastpython.com/threading-in-python/index

Illustrates setting a default timeout for threads waiting on the barrier. If the timeout expires before all threads arrive, a BrokenBarrierError is raised.

```python
# configure a barrier with a default timeout
barrier = threading.Barrier(10, timeout=5)
```

--------------------------------

### Check if a Thread is Alive (Python)

Source: https://superfastpython.com/threading-in-python/index

Demonstrates how to check if a `threading.Thread` instance is alive using the `is_alive()` method. Initially, a thread is not alive. After starting, it becomes alive until its execution completes. The `join()` method can be used to wait for thread completion.

```python
# SuperFastPython.com
# example of assessing whether a thread is alive
from threading import Thread

# create the thread
thread = Thread()

# report the thread is alive
print(thread.is_alive())
```

```python
# SuperFastPython.com
# example of assessing whether a running thread is alive
from time import sleep
from threading import Thread

# create the thread
thread = Thread(target=lambda:sleep(1))

# report the thread is alive
print(thread.is_alive())

# start the thread
thread.start()

# report the thread is alive
print(thread.is_alive())

# wait for the thread to finish
thread.join()

# report the thread is alive
print(thread.is_alive())
```

--------------------------------

### Context Manager for Lock Acquisition in Python

Source: https://superfastpython.com/threading-in-python/index

Shows the recommended and concise way to manage locks in Python using the `with` statement (context manager). This automatically handles acquiring and releasing the lock, ensuring it's always released upon exiting the block.

```python
import threading

lock = threading.Lock()

# acquire the lock using a context manager
with lock:
    # critical section...
```

--------------------------------

### Get Native Thread Identifier using threading.get_native_id()

Source: https://superfastpython.com/threading-in-python/index

Retrieve the native thread identifier assigned by the operating system for the current thread. This is achieved using the `threading.get_native_id()` function. Similar to the Python identifier, the native ID will vary with each execution.

```python
# SuperFastPython.com
# report the native id for the current thread
from threading import get_native_id

# get the native id for the current thread
identifier = get_native_id()

# report the thread id
print(identifier)
```

--------------------------------

### Using Try-Finally for Lock Management in Python

Source: https://superfastpython.com/threading-in-python/index

Illustrates a more robust, though verbose, method for managing locks using a try-finally block. This ensures that the lock is released even if exceptions are raised within the critical section.

```python
import threading

lock = threading.Lock()

# acquire the lock
lock.acquire()
try:
    # critical section...
finally:
    # always release the lock
    lock.release()
```

--------------------------------

### Get Python Thread Identifier using threading.get_ident()

Source: https://superfastpython.com/threading-in-python/index

Retrieve the unique Python thread identifier for the current thread. This identifier is assigned by the Python interpreter and can be obtained using the `threading.get_ident()` function. The identifier will differ each time the code is run.

```python
# SuperFastPython.com
# report the id for the current thread
from threading import get_ident

# get the id for the current thread
identifier = get_ident()

# report the thread id
print(identifier)
```

--------------------------------

### Join a Thread in Python

Source: https://superfastpython.com/threading-in-python/index

Demonstrates how to wait for a thread to complete its execution using the Thread.join() method. This blocks the current thread until the target thread terminates.

```python
# join a thread
thread.join()
```

--------------------------------

### Initialize a Lock Object in Python

Source: https://superfastpython.com/threading-in-python/index

Demonstrates the basic step of creating an instance of a lock object in Python using the threading.Lock class. This lock will be used to synchronize access to shared resources, such as a counter, across multiple threads.

```python
# create a lock
lock = Lock()
```

--------------------------------

### Implement Countdown Latch in Python

Source: https://superfastpython.com/threading-in-python/index

A custom implementation of a countdown latch using Python's threading.Condition. It allows threads to wait until a specified count reaches zero. The latch starts closed and opens once the count is reached, notifying all waiting threads.

```python
from threading import Condition

class CountDownLatch():
    def __init__(self, count):
        self.count = count
        self.condition = Condition()

    def count_down(self):
        with self.condition:
            if self.count == 0:
                return
            self.count -= 1
            if self.count == 0:
                self.condition.notify_all()

    def wait(self):
        with self.condition:
            if self.count == 0:
                return
            self.condition.wait()
```

--------------------------------

### Enumerate Active Threads using threading.enumerate()

Source: https://superfastpython.com/threading-in-python/index

Obtain a list of all currently active (alive) threads within a Python process using `threading.enumerate()`. The list always includes the main thread. The example iterates through the list and prints the name of each active thread.

```python
# SuperFastPython.com
# enumerate all active threads
import threading

# get a list of all active threads
threads = threading.enumerate()

# report the name of all active threads
for thread in threads:
    print(thread.name)
```

--------------------------------

### Use Context Manager for Thread Condition in Python

Source: https://superfastpython.com/threading-in-python/index

Illustrates using the 'with' statement (context manager) for acquiring and releasing a threading.Condition object. This simplifies the code by automatically handling the acquire and release operations, making it safer and more readable.

```python
# acquire the condition
with condition:
    # wait to be notified
    condition.wait()
```

--------------------------------

### Query Default Thread Name in Python

Source: https://superfastpython.com/threading-in-python/index

Shows how to access the default name assigned to a `threading.Thread` instance. Threads are automatically named in a unique manner within each process, typically in the format 'Thread-%d'. This example creates a thread and prints its default name.

```python
# SuperFastPython.com
# example of accessing the thread name
from threading import Thread

# create the thread
thread = Thread()

# report the thread name
print(thread.name)
```

--------------------------------

### Execute a Command and Capture Output in Python

Source: https://superfastpython.com/threading-in-python/index

This snippet demonstrates how to execute an external command using `subprocess.Popen` in Python and capture its standard output and standard error. It's useful for running shell commands and processing their results within a Python script. Note that `shell=True` can be a security risk if the command is not trusted.

```python
import subprocess

my_cmd = 'nohup ./your_executable_name &'
result = subprocess.Popen(my_cmd, shell=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
stdout, stderr = result.communicate()
```

--------------------------------

### Use Context Manager for Lock Protection in Python

Source: https://superfastpython.com/threading-in-python/index

Shows a more concise way to manage locks in Python using the 'with' statement (context manager). This approach automatically acquires the lock before entering the block and releases it upon exiting, simplifying thread-safe code and reducing the risk of forgetting to release the lock.

```python
# acquire the lock protecting the counter
with lock:
    # update the counter
    counter += 1
```

--------------------------------

### Python Spinlock with Timeout

Source: https://superfastpython.com/threading-in-python/index

This Python code demonstrates a spinlock using a timeout for acquiring the lock. The `acquire(timeout=0.1)` method attempts to get the lock for a specified duration, preventing indefinite busy-waiting and allowing the thread to proceed if the lock isn't acquired within the timeout.

```python
while True:
    # try and get the lock with a timeout
    acquired = lock.acquire(timeout=0.1)
    # check if we got the lock
    if acquired:
        # stop waiting
        break
```

--------------------------------

### Python Mutex Lock Example

Source: https://superfastpython.com/threading-in-python/index

Demonstrates using a threading.Lock to protect a critical section in a multithreaded Python application. The lock ensures that only one thread can access the shared resource (printing and sleeping) at a time, preventing race conditions. It requires the 'threading' and 'time' modules.

```python
# SuperFastPython.com
# example of a mutual exclusion (mutex) lock
from time import sleep
from random import random
from threading import Thread
from threading import Lock

# work function
def task(lock, identifier, value):
    # acquire the lock
    with lock:
        print(f'>thread {identifier} got the lock, sleeping for {value}')
        sleep(value)

# create a shared lock
lock = Lock()

# start a few threads that attempt to execute the same critical section
for i in range(10):
    # start a thread
    Thread(target=task, args=(lock, i, random())).start()

# wait for all threads to finish...

```

--------------------------------

### Waiting for Thread Results in Python

Source: https://superfastpython.com/threading-in-python/index

Explores common strategies for retrieving results from a new thread in Python. It outlines indirect methods like using instance variables, queues, or global variables, as direct result retrieval is not supported.

```python
# Method 1: Use instance variables on an extended threading.Thread
# Method 2: Use a queue.Queue to share a result between threads
# Method 3: Use a global variable to share a result between threads
```

--------------------------------

### Python Task Function for Livelock Example

Source: https://superfastpython.com/threading-in-python/index

Defines a task function for worker threads that attempts to acquire two locks in a specific order. If the second lock is unavailable, it releases the first lock and retries, potentially leading to a livelock. It requires the 'threading' module for locks and the 'time' module for sleeping.

```python
from threading import Lock
from time import sleep

def task(number, lock1, lock2):
    # loop until the task is completed
    while True:
        # acquire the first lock
        with lock1:
            # wait a moment
            sleep(0.1)
            # check if the second lock is available
            if lock2.locked():
                print(f'Task {number} cannot get the second lock, giving up...')
            else:
                # acquire lock2
                with lock2:
                    print(f'Task {number} made it, all done.')
                    break
```

--------------------------------

### Reset Barrier in Python

Source: https://superfastpython.com/threading-in-python/index

Demonstrates how to reset a broken barrier. The reset() function makes the barrier usable again, allowing threads to synchronize on it.

```python
# reset a broken barrier
barrier.reset()
```

--------------------------------

### Python: Thread-Local Data Storage with threading.local

Source: https://superfastpython.com/threading-in-python/index

Illustrates thread-local data storage using the threading.local class. Each thread can store and access its own data using properties on a local instance, preventing data conflicts between threads. This is achieved by creating a threading.local() instance and assigning attributes to it within each thread.

```python
# create a local instance
local = threading.local()

# store some data
local.custom = 33
```

```python
# SuperFastPython.com
# example of thread local storage
from time import sleep
import threading

# custom target function
def task(value):
    # create a local storage
    local = threading.local()
    # store data
    local.value = value
    # block for a moment
    sleep(value)
    # retrieve value
    print(f'Stored value: {local.value}')

# create and start a thread
threading.Thread(target=task, args=(1,)).start()

# create and start another thread
threading.Thread(target=task, args=(2,)).start()
```
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