新增thread readme

2024-04-19 22:09:56 +08:00 · 2024-04-19 22:09:56 +08:00 · 1a9cda80ff
commit 1a9cda80ff
parent a47075e5f0
1 changed files with 282 additions and 0 deletions
--- a/Thread/README.md
+++ b/Thread/README.md
@ -0,0 +1,282 @@
+# 多工
+### 用到多工場合:
+* 同時間須顯示許多資料
+* 讀取model和AI運算
+* 需要長時間掛在背景執行
+### 線程/進程 差異
+* 多線程(Thread)
+
+	簡單講:一個人有2隻手，然後可以同時進行
+
+* 多進程(Process)
+
+	簡單講:聯合其他人一起做
+##
+## 多線程
+### 正常使用
+#### 2個線程幾乎同時啟動
+```
+import threading
+from queue import Queue #Thread 無法回傳值，所以要使用 Queue.put() 將要傳回的值存入 Queue，再用 Queue.get() 取出
+import time
+import os
+# A報數
+def A_Count_off():
+    for i in range(0,5):
+        print(f'A : {i}')
+        time.sleep(0.5)
+
+
+# B報數
+def B_Count_off():
+    for i in range(5,10):
+        print(f'B : {i}')
+        time.sleep(0.5)
+
+
+
+thread_list=[A_Count_off,B_Count_off]
+thread_num =[]
+for i in range(0,len(thread_list)):
+    thread_num.append(threading.Thread(target=thread_list[i]))
+
+for i in range(0,len(thread_num)):
+    thread_num[i].join()
+
+
+```
+### 非正常使用
+#### 第2個線程要等到第1個線程運行完才會啟動
+##### 失去多線程意義
+```
+# A報數
+def A_Count_off():
+    for i in range(0,5):
+        print(f'A : {i}')
+        time.sleep(0.5)
+
+
+# B報數
+def B_Count_off():
+    for i in range(5,10):
+        print(f'B : {i}')
+        time.sleep(0.5)
+
+
+
+thread_list=[A_Count_off,B_Count_off]
+thread_num =[]
+
+for i in range(0,len(thread_num)):
+    thread_num[i].start()
+    thread_num[i].join()
+
+
+```
+### 攜帶參數
+```
+def Count_off(code_name):
+    print('process {} '.format(os.getpid()))
+    print('thread {} '.format(threading.current_thread().name))
+    for i in range(0,5):
+        print(f'{code_name} : {i}')
+        time.sleep(0.5)
+
+
+thread_name_list=["A","B","C","D"]
+
+thread_list=[]
+for i in range(0,len(thread_name_list)):
+    thread_list.append(threading.Thread(target=Count_off,args=thread_name_list[i])) # 攜帶參數
+for i in range(0,len(thread_list)):
+    thread_list[i].start()
+for i in range(0,len(thread_list)):
+    thread_list[i].join()
+
+```
+
+### 使用class的方式(推薦使用)
+#### 後續觀看程式碼及維護，會提高不少
+* start會使用分出去的線程
+* run會使用主線程
+```
+class Thread_class(threading.Thread):
+    def __init__(self,code_name):
+        threading.Thread.__init__(self)
+        self.code_name = code_name
+
+    def run(self):
+        print('process {} '.format(os.getpid()))  # 查看進程
+        print('thread {} '.format(threading.current_thread().name))  # 查看線程
+        for i in range(0,5):
+            print(f'{self.code_name} : {i}')
+            time.sleep(0.5)
+    def test_return(self):
+        return(f'{self.code_name}=END')
+thread_name_list=["A","B","C","D"]
+thread_list=[]
+for i in range(0,len(thread_name_list)):
+    thread_list.append(Thread_class(thread_name_list[i]))
+for i in range(0,len(thread_list)):
+    thread_list[i].start()  # 啟動額外線程
+for i in range(0,len(thread_list)):
+    thread_list[i].join()
+    
+```
+
+```
+class Thread_class(threading.Thread):
+    def __init__(self,code_name):
+        threading.Thread.__init__(self)
+        self.code_name = code_name
+
+    def run(self):
+        print('process {} '.format(os.getpid()))  # 查看進程
+        print('thread {} '.format(threading.current_thread().name))  # 查看線程
+        for i in range(0,5):
+            print(f'{self.code_name} : {i}')
+            time.sleep(0.5)
+    def test_return(self):
+        return(f'{self.code_name}=END')
+thread_name_list=["A","B","C","D"]
+thread_list=[]
+for i in range(0,len(thread_name_list)):
+    thread_list.append(Thread_class(thread_name_list[i]))
+for i in range(0,len(thread_list)):
+    thread_list[i].run()  # 這樣只會套用到 呼叫method,會用主線程去調用
+for i in range(0,len(thread_list)):
+    thread_list[i].join()
+```
+
+### Qthread:
+* 使用方式與thread相似
+* 多了信號槽使用(可以擁有多個)
+* 方便與主UI的線程溝通
+```
+class ReadTime(QtCore.QThread):  # 讀取時間
+    time_out = pyqtSignal(str)  # 聲明一個帶字串參數的信號槽
+    def __init__(self, parent=None):
+        super().__init__(parent)
+    def run(self):
+        while True:
+            result = time.strftime("%Y-%m-%d %H:%M:%S", time.localtime())  # 讀取當下時間
+            self.time_out.emit(f'{result}')  # 傳送信号
+            self.msleep(500)  # 休眠0.5秒
+```
+## 
+## 多進程
+### 多進程與多線程的寫法極為相似
+#### 正常使用:
+#### 2個進程幾乎同時啟動
+```
+# A報數
+def A_Count_off():
+    for i in range(0,5):
+        print(f'A : {i}')
+        time.sleep(0.5)
+
+
+# B報數
+def B_Count_off():
+    for i in range(5,10):
+        print(f'B : {i}')
+        time.sleep(0.5)
+
+
+if __name__=='__main__':
+    process_list=[A_Count_off,B_Count_off]
+    process_name =[]
+    for i in range(0,len(process_list)):
+        process_name.append(mp.Process(target=process_list[i]))
+        
+    for i in range(0,len(process_name)):
+        process_name[i].start()
+        
+    for i in range(0,len(process_name)):
+        process_name[i].join()
+```
+### 非正常使用:
+#### 第2個進程要等到第1個進程運行完才會啟動
+#### 失去多進程意義
+
+```
+# A報數
+def A_Count_off():
+    for i in range(0,5):
+        print(f'A : {i}')
+        time.sleep(0.5)
+
+
+# B報數
+def B_Count_off():
+    for i in range(5,10):
+        print(f'B : {i}')
+        time.sleep(0.5)
+
+
+if __name__=='__main__':
+    process_list=[A_Count_off,B_Count_off]
+    process_name =[]
+    for i in range(0,len(process_list)):
+        process_name.append(mp.Process(target=process_list[i]))
+        
+    for i in range(0,len(process_name)):
+        process_name[i].start()
+        process_name[i].join()
+        
+
+```
+
+### 攜帶參數 
+```
+if __name__=='__main__':
+    process_name_list=["A","B","C","D"]
+    process_list=[]
+    for i in range(0,len(process_name_list)):
+        process_list.append(mp.Process(target=Count_off,args=process_name_list[i])) # 攜帶參數
+```
+### 使用class的方式(推薦使用)
+#### 後續觀看程式碼及維護，會提高不少
+* start會使用分出去的進程
+* run會使用主線程
+* 但start後，無法直接調用此class的參數，等等會大概說明
+```
+class Process_class(mp.Process):
+    def __init__(self, code_name):
+        mp.Process.__init__(self)
+        self.code_name = code_name
+
+    def run(self):
+        print('process {} '.format(os.getpid())) # 查看進程
+        print('thread {} '.format(threading.current_thread().name)) # 查看線程
+        for i in range(0,5):
+            print(f'{self.code_name} : {i}')
+            time.sleep(0.5)
+    def test_return(self):
+        return(f'{self.code_name}=END')
+
+if __name__=='__main__':
+    start_time = time.time()
+    process_name_list = ["A", "B", "C", "D"]
+    process_list = []
+    for i in range(0, len(process_name_list)):
+        process_list.append(Process_class(process_name_list[i]))
+    for i in range(0, len(process_list)):
+        process_list[i].start()
+    for i in range(0, len(process_list)):
+        process_list[i].join()
+
+    for i in range(0, len(process_list)):
+        print(process_list[i].test_return())
+```
+### 多進程的溝通方式
+#### 多進程的溝通方式需要透過Queue或pipe
+    參考資料
+    http://www.taroballz.com/2018/01/11/processing_communcation/
+    多線程由於共享記憶體溝通方式比多進程方便
+    2者差異的參考資料
+    https://blog.csdn.net/Victor2code/article/details/109005171
+#### 用團隊合作方式來理解，每個人都在做自己的事，若沒有溝通或是告知(Queue)，則沒有辦法獲取資料
+
+
+