adding chapter 7 source code

2021-03-31 09:22:38 +04:00
parent 9589675a50
commit f88527eef4
20 changed files with 618 additions and 0 deletions
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+# process1.py to create simple processes with function
+import os
+from multiprocessing import Process, current_process as cp
+from time import sleep
+
+def print_hello():
+    sleep(2)
+    print("{}-{}: Hello".format(os.getpid(), cp().name))
+
+
+def print_message(msg):
+    sleep(1)
+    print("{}-{}: {}".format(os.getpid(), cp().name, msg))
+
+processes = []
+
+# creating process
+processes.append(Process(target=print_hello, name="Process 1"))
+processes.append(Process(target=print_hello, name="Process 2"))
+processes.append(Process(target=print_message,
+                         args=["Good morning"], name="Process 3"))
+
+# start the process
+for p in processes:
+    p.start()
+
+# wait till all are done
+for p in processes:
+    p.join()
+
+print("Exiting the main process")
@@ -0,0 +1,15 @@
+# process2.py to create processes using a pool
+import os
+from multiprocessing import Process, Pool, current_process as cp
+from time import sleep
+
+def print_message(msg):
+    sleep(1)
+    print("{}-{}: {}".format(os.getpid(), cp().name, msg))
+
+# creating process from a pool
+with Pool(3) as proc:
+    proc.map(print_message, ["Orange", "Apple", "Banana",
+                             "Grapes","Pears"])
+
+print("Exiting the main process")
@@ -0,0 +1,28 @@
+# process3.py to use shared memory ctype objects
+
+import multiprocessing
+from multiprocessing import Process, Pool, current_process as cp
+
+def inc_sum_list(list, inc_list, sum):
+    sum.value = 0
+
+    for index, num in enumerate(list):
+        inc_list[index] = num + 1
+        sum.value = sum.value + inc_list[index]
+
+
+mylist = [2, 5, 7]
+
+inc_list = multiprocessing.Array('i', 3)
+
+sum = multiprocessing.Value('i')
+
+p = Process(target=inc_sum_list,
+            args=(mylist, inc_list, sum))
+
+p.start()
+p.join()
+print("incremented list: ", list(inc_list))
+print("sum of inc list: ", sum.value)
+
+print("Exiting the main process")
@@ -0,0 +1,29 @@
+# process4.py to use shared memory using the server process
+
+import multiprocessing
+from multiprocessing import Process
+
+def insert_data (dict1, code, subject):
+    dict1[code] =  subject
+
+def output(dict1):
+    print("Dictionary data: ", dict1)
+
+with multiprocessing.Manager() as mgr:
+    # create a dictionary in the server process
+    mydict = mgr.dict({100: "Maths", 200: "Science"})
+
+    p1 = Process(target=insert_data, args=(mydict, 300, "English"))
+    p2 = Process(target=insert_data, args=(mydict, 400, "French"))
+    p3 = Process(target=output, args=(mydict,))
+
+    p1.start()
+    p2.start()
+
+    p1.join()
+    p2.join()
+
+    p3.start()
+    p3.join()
+
+print("Exiting the main process")
@@ -0,0 +1,26 @@
+# process5.py to use queue to exchange data
+
+from multiprocessing import Process
+from multiprocessing import Queue
+
+def copy_data (list, myqueue):
+    for num in list:
+        myqueue.put(num)
+
+def output(myqueue):
+    while not myqueue.empty():
+        print(myqueue.get())
+
+mylist = [2, 5, 7]
+myqueue = Queue()
+
+p1 = Process(target=copy_data, args=(mylist, myqueue))
+p2 = Process(target=output, args=(myqueue,))
+
+p1.start()
+p1.join()
+p2.start()
+p2.join()
+
+print("Queue is empty: ",myqueue.empty())
+print("Exiting the main process")
@@ -0,0 +1,29 @@
+# process6.py to use Pipe to exchange data
+
+from multiprocessing import Process, Pipe
+
+def mysender (s_conn):
+    s_conn.send({100: "Maths"})
+    s_conn.send({200: "Science"})
+    s_conn.send("BYE")
+    s_conn.close()
+
+def myreceiver(r_conn):
+    while True:
+        msg = r_conn.recv()
+        if msg == "BYE":
+            break
+        print("Received message : ", msg)
+    r_conn.close()
+sender_conn, receiver_conn= Pipe()
+
+p1 = Process(target=mysender, args=(sender_conn, ))
+p2 = Process(target=myreceiver, args=(receiver_conn,))
+
+p1.start()
+p2.start()
+
+p1.join()
+p2.join()
+
+print("Exiting the main process")
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+# process7.py to show synchronization and locking
+from functools import partial
+from multiprocessing import Pool, Manager
+
+def printme (lock, msg):
+    lock.acquire()
+    try:
+        print(msg)
+    finally:
+        lock.release()
+
+with Pool(3) as proc:
+    lock = Manager().Lock()
+    func = partial(printme,lock)
+    proc.map(func, ["Orange", "Apple", "Banana",
+                             "Grapes","Pears"])
+
+print("Exiting the main process")
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+#processes_casestudy.py
+
+import time
+from multiprocessing import Process, JoinableQueue
+from getfilelistpy import getfilelist
+import gdown
+
+PROCESSES_POOL_SIZE = 5
+
+#update the resource object as per your API key and the gdriver folder id
+resource = {
+    "api_key": "AIzaSyDYKmm85keqnk4bDpYa2bxddKrGns4z0",
+    "id": "0B8TxHW2Ci6dbckVweTRtV3RUU",
+    "fields": "files(name,id,webContentLink)",
+}
+
+def mydownloader( queue):
+    while True:
+        # Get the file id and name from the queue
+        item1 =  queue.get()
+        try:
+            gdown.download(item1['webContentLink'],
+                           './files/{}'.format(item1['name']),
+                           quiet=False)
+        finally:
+            queue.task_done()
+
+
+def get_files(resource):
+    res = getfilelist.GetFileList(resource)
+    files_list = res['fileList'][0]
+    return files_list
+
+def main ():
+
+    files = get_files(resource)
+    #add files info into the queue
+    myqueue = JoinableQueue()
+    for item in files['files']:
+        myqueue.put(item)
+
+    processes = []
+    for id in range(PROCESSES_POOL_SIZE):
+        p = Process(target=mydownloader,
+                    args=(myqueue,))
+        p.daemon = True
+        p.start()
+
+    start_time = time.monotonic()
+    myqueue.join()
+    total_exec_time = time.monotonic() - start_time
+
+    print(f'Time taken to download: {total_exec_time:.2f} seconds')
+
+main()