I want to pass named arguments to the target function, while creating a Thread object.
Following is the code that I have written:
import threading def f(x=None, y=None): print x,y t = threading.Thread(target=f, args=(x=1,y=2,)) t.start()
I get a syntax error for "x=1", in Line 6. I want to know how I can pass keyword arguments to the target function.
Example 1 - Thread Argument Passing long taskids[NUM_THREADS]; for(t=0; t<NUM_THREADS; t++) { taskids[t] = t; printf("Creating thread %ld\n", t); rc = pthread_create(&threads[t], NULL, PrintHello, (void *) taskids[t]); ... } See the source code.
In Python, the method threading. active_co unt() from the threading module is used to count the currently active or running threads.
In fact, a Python process cannot run threads in parallel but it can run them concurrently through context switching during I/O bound operations. This limitation is actually enforced by GIL. The Python Global Interpreter Lock (GIL) prevents threads within the same process to be executed at the same time.
What does the target argument to the constructor of thread represent in Python? Thread class Constructor It is reserved for future extension. target : This is the callable object or task to be invoked by the run() method.
t = threading.Thread(target=f, kwargs={'x': 1,'y': 2})
this will pass a dictionary with the keyword arguments' names as keys and argument values as values in the dictionary. the other answer above won't work, because the "x" and "y" are undefined in that scope.
another example, this time with multiprocessing, passing both positional and keyword arguments:
the function used being:
def f(x, y, kw1=10, kw2='1'): pass
and then when called using multiprocessing:
p = multiprocessing.Process(target=f, args=('a1', 2,), kwargs={'kw1': 1, 'kw2': '2'})
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