In Python’s `threading` module, the `is_alive()` method is used to check whether a thread is currently active and running. Here’s an explanation of how to use `is_alive()` with an example
In python threading module the is_alive()
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import threading
import time
def thread_function():
print("Thread is running...")
time.sleep(2)
print("Thread is exiting...")
threading.Thread(target=thread_function)
thread.start()
if thread.is_alive():
print("Thread is active.")
else:
print("Thread is not active.")
thread.join()
if thread.is_alive():
print("Thread is still active after joining.")
else:
print("Thread has completed and is not active.")
Output
Thread is running
Thread is active
Thread is execute
Thread is active not complete
Explanation
1. **Defining the Thread Function**:
– `thread_function()` is a simple function that prints messages and then sleeps for 2 seconds.
2. **Creating a Thread**:
– `thread = threading.Thread(target=thread_function)` creates a `Thread` object named `thread`, targeting the `thread_function` as its execution target.
3. **Starting the Thread**:
– `thread.start()` initiates the execution of the thread by invoking the `thread_function()`.
4. **Checking if the Thread is Alive**:
– `thread.is_alive()` is used to check if the thread is currently active and running. Initially, it will return `True` because the thread has been started but not yet completed.
5. **Joining the Thread**:
– `thread.join()` is called to wait for the thread to complete its execution. This ensures that the main program waits until the thread finishes before proceeding.
6. **Re-checking if the Thread is Alive**:
– After joining, `thread.is_alive()` is checked again. Now, it should return `False` because the thread has completed its execution.
When you run the above code, the expected output will be:
Thread is running…
Thread is active.
Thread is exiting…
Thread has completed and is not active.
Summary
`is_alive()` is a method available on `Thread` objects in Python’s `threading` module.
– It returns `True` if the thread is currently executing and `False` otherwise.
– Use `is_alive()` to dynamically check the status of a thread during its lifecycle, such as before and after joining to determine if it’s still active or has completed.