Python 多处理模块快速指南及示例

from multiprocessing import processdef print_numbers():    for i in range(5):        print(i)p = process(target=print_numbers)p.start()  # starts a new processp.join()   # waits for the process to finish

p = process(target=print_numbers)p.start()  # runs the target function in a separate process

p = process(target=print_numbers)p.start()p.join(2)  # waits up to 2 seconds for the process to finish

p = process(target=print_numbers)p.start()print(p.is_alive())  # true if the process is still running

from multiprocessing import current_processdef print_current_process():    print(current_process())p = process(target=print_current_process)p.start()  # prints the current process info

p1 = process(target=print_numbers)p2 = process(target=print_numbers)p1.start()p2.start()print(process.active_children())  # lists all active child processes

from multiprocessing import cpu_countprint(cpu_count())  # returns the number of cpus on the machine

from multiprocessing import pooldef square(n):    return n * nwith pool(4) as pool:  # pool with 4 worker processes    result = pool.map(square, [1, 2, 3, 4, 5])print(result)  # [1, 4, 9, 16, 25]

from multiprocessing import process, queuedef put_data(q):    q.put([1, 2, 3])def get_data(q):    data = q.get()    print(data)q = queue()p1 = process(target=put_data, args=(q,))p2 = process(target=get_data, args=(q,))p1.start()p2.start()p1.join()p2.join()

from multiprocessing import process, locklock = lock()def print_numbers():    with lock:        for i in range(5):            print(i)p1 = process(target=print_numbers)p2 = process(target=print_numbers)p1.start()p2.start()p1.join()p2.join()

from multiprocessing import process, valuedef increment(val):    with val.get_lock():        val.value += 1shared_val = value('i', 0)processes = [process(target=increment, args=(shared_val,)) for _ in range(10)]for p in processes:    p.start()for p in processes:    p.join()print(shared_val.value)  # output will be 10

from multiprocessing import process, pipedef send_message(conn):    conn.send("hello from child")    conn.close()parent_conn, child_conn = pipe()p = process(target=send_message, args=(child_conn,))p.start()print(parent_conn.recv())  # receives data from the child processp.join()

from multiprocessing import process, managerdef modify_list(shared_list):    shared_list.append("new item")with manager() as manager:    shared_list = manager.list([1, 2, 3])    p = process(target=modify_list, args=(shared_list,))    p.start()    p.join()    print(shared_list)  # [1, 2, 3, "new item"]

from multiprocessing import Process, Semaphoreimport timesem = Semaphore(2)  # Only 2 processes can access the resourcedef limited_access():    with sem:        print("Accessing resource")        time.sleep(2)processes = [Process(target=limited_access) for _ in range(5)]for p in processes:    p.start()for p in processes:    p.join()