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建設(shè)醫(yī)療網(wǎng)站,怎樣注冊一個自己的平臺,濟(jì)南商城網(wǎng)站建設(shè)公司,免費永久vps服務(wù)器? 一、多任務(wù) 1.1 概念多任務(wù)就是指：同一時間能執(zhí)行多個任務(wù)。比方我們的電腦能一邊QQ聊天，一邊寫論文，還能聽歌。 1.2 多任務(wù)的優(yōu)勢： 多任務(wù)的最大好處是充分利用CPU資源，提高程序的執(zhí)行效率。 1.3 多任務(wù)的兩種表…

多任務(wù)就是指：同一時間能執(zhí)行多個任務(wù)。比方我們的電腦能一邊QQ聊天，一邊寫論文，還能聽歌。

1.2 多任務(wù)的優(yōu)勢：

多任務(wù)的最大好處是充分利用CPU資源，提高程序的執(zhí)行效率。

1.3 多任務(wù)的兩種表現(xiàn)形式：

（1）并發(fā)：

在一段時間內(nèi)交替去執(zhí)行多個任務(wù)。

例子：

對于單核CPU處理多任務(wù)，操作系統(tǒng)輪流讓各個任務(wù)交替執(zhí)行。如下圖所示：
在這里插入圖片描述

（2）并行：

在一段時間內(nèi)真正的同時一起執(zhí)行多個任務(wù)。

例子：

對于多核cpu處理多任務(wù)，操作系統(tǒng)會給cpu的每個內(nèi)核安排一個執(zhí)行的任務(wù)，多個內(nèi)核是真正的一起同時執(zhí)行多個任務(wù)。這里需要注意多核cpu是并行的執(zhí)行多任務(wù)，始終有多個任務(wù)一起執(zhí)行。

在這里插入圖片描述

二、進(jìn)程：

在python中，想要實現(xiàn)多任務(wù)，可以使用多進(jìn)程來實現(xiàn)。

2.1 進(jìn)程的概念：

進(jìn)程(Process) 是資源分配的最小單位，它是操作系統(tǒng)進(jìn)行資源分配和調(diào)度運行的基本單位，通俗理解: 一個正在運行的程序就是一個進(jìn)程。例如：正在運行的qq,微信等，他們都是一個進(jìn)程。
注意：一個正在運行的程序才叫進(jìn)程，而沒有運行的程序，只能叫程序，不能叫進(jìn)程。
同時，一個程序可以有一個或者多個進(jìn)程。

2.2 多進(jìn)程的作用：

在這里插入圖片描述

上圖中是一個非常簡單的程序，一旦運行hello.py這個程序，按照代碼的執(zhí)行順序,?func_ a函數(shù)執(zhí)行完畢后才能執(zhí)行func_ b函數(shù)。如果可以讓func a和func _b同時運行,顯然執(zhí)行hello.py這個程序的效率會大大提升。
那怎么實現(xiàn)呢？接著看：

如下圖所示，當(dāng)運行hello.py這個程序的時候，先創(chuàng)建一個主進(jìn)程，之后再創(chuàng)建了一個子進(jìn)程，讓主進(jìn)程執(zhí)行func_a，讓子進(jìn)程執(zhí)行func_b，這樣就使用多進(jìn)程實現(xiàn)了多任務(wù)。

在這里插入圖片描述

2.3 多進(jìn)程完成多任務(wù)：

（1）進(jìn)程的創(chuàng)建步驟：

1、導(dǎo)入進(jìn)程包：

<span style="color:rgba(0, 0, 0, 0.75)"><span style="background-color:#ffffff"><span style="color:#000000"><span style="background-color:#282a36"><code class="language-python"><span style="color:#ff79c6">import</span> multiprocessing
</code></span></span></span></span>

2、通過進(jìn)程類創(chuàng)建進(jìn)程對象：

<span style="color:rgba(0, 0, 0, 0.75)"><span style="background-color:#ffffff"><span style="color:#000000"><span style="background-color:#282a36"><code class="language-python">進(jìn)程對象 <span style="color:#6272a4">=</span> multiprocessing<span style="color:#999999">.</span>Process<span style="color:#999999">(</span>target<span style="color:#6272a4">=</span>任務(wù)名<span style="color:#999999">)</span>
</code></span></span></span></span>

在這里插入圖片描述

3、啟動進(jìn)程執(zhí)行任務(wù)：

<span style="color:rgba(0, 0, 0, 0.75)"><span style="background-color:#ffffff"><span style="color:#000000"><span style="background-color:#282a36"><code class="language-python">進(jìn)程對象<span style="color:#999999">.</span>start<span style="color:#999999">(</span><span style="color:#999999">)</span>
</code></span></span></span></span>

在這里插入圖片描述

（2）多進(jìn)程例子：

下面程序是單進(jìn)程，先執(zhí)行唱歌的函數(shù)，再執(zhí)行跳舞的函數(shù)。需要3秒完成。

<span style="color:rgba(0, 0, 0, 0.75)"><span style="background-color:#ffffff"><span style="color:#000000"><span style="background-color:#282a36"><code class="language-python"><span style="color:#ff79c6">import</span> time<span style="color:#6272a4"># 唱歌</span>
<span style="color:#ff79c6">def</span> <span style="color:#8be9fd">sing</span><span style="color:#999999">(</span><span style="color:#999999">)</span><span style="color:#999999">:</span><span style="color:#ff79c6">for</span> i <span style="color:#ff79c6">in</span> <span style="color:#f1fa8c">range</span><span style="color:#999999">(</span><span style="color:#f1fa8c">3</span><span style="color:#999999">)</span><span style="color:#999999">:</span><span style="color:#ff79c6">print</span><span style="color:#999999">(</span><span style="color:#f1fa8c">"唱歌..."</span><span style="color:#999999">)</span>time<span style="color:#999999">.</span>sleep<span style="color:#999999">(</span><span style="color:#f1fa8c">0.5</span><span style="color:#999999">)</span> <span style="color:#6272a4"># 延遲0.5秒</span>
<span style="color:#6272a4"># 跳舞</span>
<span style="color:#ff79c6">def</span> <span style="color:#8be9fd">dance</span><span style="color:#999999">(</span><span style="color:#999999">)</span><span style="color:#999999">:</span><span style="color:#ff79c6">for</span> i <span style="color:#ff79c6">in</span> <span style="color:#f1fa8c">range</span><span style="color:#999999">(</span><span style="color:#f1fa8c">3</span><span style="color:#999999">)</span><span style="color:#999999">:</span><span style="color:#ff79c6">print</span><span style="color:#999999">(</span><span style="color:#f1fa8c">"跳舞..."</span><span style="color:#999999">)</span>time<span style="color:#999999">.</span>sleep<span style="color:#999999">(</span><span style="color:#f1fa8c">0.5</span><span style="color:#999999">)</span>
<span style="color:#ff79c6">if</span> __name__ <span style="color:#6272a4">==</span> <span style="color:#f1fa8c">"__main__"</span><span style="color:#999999">:</span>sing<span style="color:#999999">(</span><span style="color:#999999">)</span>dance<span style="color:#999999">(</span><span style="color:#999999">)</span>
</code></span></span></span></span>

運行結(jié)果：
在這里插入圖片描述

上面的程序怎么使用多進(jìn)程實現(xiàn)呢？下面的程序?qū)崿F(xiàn)了多進(jìn)程實現(xiàn)多任務(wù)，我們會發(fā)現(xiàn)，只需要1.5秒執(zhí)行完了，唱歌和跳舞是交替執(zhí)行的。

<span style="color:rgba(0, 0, 0, 0.75)"><span style="background-color:#ffffff"><span style="color:#000000"><span style="background-color:#282a36"><code class="language-python"><span style="color:#6272a4"># 1.導(dǎo)入進(jìn)程包</span>
<span style="color:#ff79c6">import</span> time
<span style="color:#ff79c6">import</span> multiprocessing<span style="color:#6272a4"># 唱歌</span>
<span style="color:#ff79c6">def</span> <span style="color:#8be9fd">sing</span><span style="color:#999999">(</span><span style="color:#999999">)</span><span style="color:#999999">:</span><span style="color:#ff79c6">for</span> i <span style="color:#ff79c6">in</span> <span style="color:#f1fa8c">range</span><span style="color:#999999">(</span><span style="color:#f1fa8c">3</span><span style="color:#999999">)</span><span style="color:#999999">:</span><span style="color:#ff79c6">print</span><span style="color:#999999">(</span><span style="color:#f1fa8c">"唱歌..."</span><span style="color:#999999">)</span>time<span style="color:#999999">.</span>sleep<span style="color:#999999">(</span><span style="color:#f1fa8c">0.5</span><span style="color:#999999">)</span> <span style="color:#6272a4"># 延遲0.5秒</span><span style="color:#6272a4"># 跳舞</span>
<span style="color:#ff79c6">def</span> <span style="color:#8be9fd">dance</span><span style="color:#999999">(</span><span style="color:#999999">)</span><span style="color:#999999">:</span><span style="color:#ff79c6">for</span> i <span style="color:#ff79c6">in</span> <span style="color:#f1fa8c">range</span><span style="color:#999999">(</span><span style="color:#f1fa8c">3</span><span style="color:#999999">)</span><span style="color:#999999">:</span><span style="color:#ff79c6">print</span><span style="color:#999999">(</span><span style="color:#f1fa8c">"跳舞..."</span><span style="color:#999999">)</span>time<span style="color:#999999">.</span>sleep<span style="color:#999999">(</span><span style="color:#f1fa8c">0.5</span><span style="color:#999999">)</span><span style="color:#ff79c6">if</span> __name__ <span style="color:#6272a4">==</span> <span style="color:#f1fa8c">"__main__"</span><span style="color:#999999">:</span><span style="color:#6272a4"># 2.使用進(jìn)程類創(chuàng)建進(jìn)程對象</span>sing_process <span style="color:#6272a4">=</span> multiprocessing<span style="color:#999999">.</span>Process<span style="color:#999999">(</span>target<span style="color:#6272a4">=</span>sing<span style="color:#999999">)</span>dance_process <span style="color:#6272a4">=</span> multiprocessing<span style="color:#999999">.</span>Process<span style="color:#999999">(</span>target<span style="color:#6272a4">=</span>dance<span style="color:#999999">)</span><span style="color:#6272a4"># 3.使用進(jìn)程對象啟動進(jìn)程執(zhí)行指定任務(wù)</span>sing_process<span style="color:#999999">.</span>start<span style="color:#999999">(</span><span style="color:#999999">)</span>dance_process<span style="color:#999999">.</span>start<span style="color:#999999">(</span><span style="color:#999999">)</span>
</code></span></span></span></span>

運行結(jié)果：
在這里插入圖片描述

2.4 進(jìn)程執(zhí)行帶有參數(shù)的任務(wù)：

（1）參數(shù)說明：

<span style="color:rgba(0, 0, 0, 0.75)"><span style="background-color:#ffffff"><span style="color:#000000"><span style="background-color:#282a36"><code class="language-python">進(jìn)程對象 <span style="color:#6272a4">=</span> multiprocessing<span style="color:#999999">.</span>Process<span style="color:#999999">(</span>target<span style="color:#6272a4">=</span>任務(wù)名<span style="color:#999999">,</span> args<span style="color:#999999">,</span> kwargs<span style="color:#999999">)</span>
</code></span></span></span></span>

在這里插入圖片描述

（2）例子：

<span style="color:rgba(0, 0, 0, 0.75)"><span style="background-color:#ffffff"><span style="color:#000000"><span style="background-color:#282a36"><code class="language-python"><span style="color:#6272a4"># 1.導(dǎo)入進(jìn)程包</span>
<span style="color:#ff79c6">import</span> time
<span style="color:#ff79c6">import</span> multiprocessing<span style="color:#6272a4"># 唱歌</span>
<span style="color:#ff79c6">def</span> <span style="color:#8be9fd">sing</span><span style="color:#999999">(</span>num<span style="color:#999999">,</span> name<span style="color:#999999">)</span><span style="color:#999999">:</span><span style="color:#ff79c6">for</span> i <span style="color:#ff79c6">in</span> <span style="color:#f1fa8c">range</span><span style="color:#999999">(</span>num<span style="color:#999999">)</span><span style="color:#999999">:</span><span style="color:#ff79c6">print</span><span style="color:#999999">(</span>name<span style="color:#999999">)</span><span style="color:#ff79c6">print</span><span style="color:#999999">(</span><span style="color:#f1fa8c">"唱歌..."</span><span style="color:#999999">)</span>time<span style="color:#999999">.</span>sleep<span style="color:#999999">(</span><span style="color:#f1fa8c">0.5</span><span style="color:#999999">)</span> <span style="color:#6272a4"># 延遲0.5秒</span><span style="color:#6272a4"># 跳舞</span>
<span style="color:#ff79c6">def</span> <span style="color:#8be9fd">dance</span><span style="color:#999999">(</span>num<span style="color:#999999">,</span> name<span style="color:#999999">)</span><span style="color:#999999">:</span><span style="color:#ff79c6">for</span> i <span style="color:#ff79c6">in</span> <span style="color:#f1fa8c">range</span><span style="color:#999999">(</span>num<span style="color:#999999">)</span><span style="color:#999999">:</span><span style="color:#ff79c6">print</span><span style="color:#999999">(</span>name<span style="color:#999999">)</span><span style="color:#ff79c6">print</span><span style="color:#999999">(</span><span style="color:#f1fa8c">"跳舞..."</span><span style="color:#999999">)</span>time<span style="color:#999999">.</span>sleep<span style="color:#999999">(</span><span style="color:#f1fa8c">0.5</span><span style="color:#999999">)</span><span style="color:#ff79c6">if</span> __name__ <span style="color:#6272a4">==</span> <span style="color:#f1fa8c">"__main__"</span><span style="color:#999999">:</span><span style="color:#6272a4"># 2.使用進(jìn)程類創(chuàng)建進(jìn)程對象</span><span style="color:#6272a4"># args:使用元組方式給指定任務(wù)傳參</span>sing_process <span style="color:#6272a4">=</span> multiprocessing<span style="color:#999999">.</span>Process<span style="color:#999999">(</span>target<span style="color:#6272a4">=</span>sing<span style="color:#999999">,</span> args<span style="color:#6272a4">=</span><span style="color:#999999">(</span><span style="color:#f1fa8c">3</span><span style="color:#999999">,</span> <span style="color:#f1fa8c">"李華"</span><span style="color:#999999">)</span><span style="color:#999999">)</span><span style="color:#6272a4"># kwargs:使用字典方式給指定任務(wù)傳參</span>dance_process <span style="color:#6272a4">=</span> multiprocessing<span style="color:#999999">.</span>Process<span style="color:#999999">(</span>target<span style="color:#6272a4">=</span>dance<span style="color:#999999">,</span> kwargs<span style="color:#6272a4">=</span><span style="color:#999999">{</span><span style="color:#f1fa8c">"num"</span><span style="color:#999999">:</span> <span style="color:#f1fa8c">2</span><span style="color:#999999">,</span> <span style="color:#f1fa8c">"name"</span><span style="color:#999999">:</span><span style="color:#f1fa8c">"小明"</span><span style="color:#999999">}</span><span style="color:#999999">)</span><span style="color:#6272a4"># 3.使用進(jìn)程對象啟動進(jìn)程執(zhí)行指定任務(wù)</span>sing_process<span style="color:#999999">.</span>start<span style="color:#999999">(</span><span style="color:#999999">)</span>dance_process<span style="color:#999999">.</span>start<span style="color:#999999">(</span><span style="color:#999999">)</span>
</code></span></span></span></span>

2.5 獲取進(jìn)程編號：

（1）作用：

當(dāng)程序中進(jìn)程的數(shù)量越來越多時，如果沒有辦法區(qū)分主進(jìn)程和子進(jìn)程還有不同的子進(jìn)程,那么就無法進(jìn)行有效的進(jìn)程管理,為了方便管理實際上每個進(jìn)程都是有自己的編號。

（2）獲取進(jìn)程編號的兩種方式：

（1）獲取當(dāng)前進(jìn)程編號：

<span style="color:rgba(0, 0, 0, 0.75)"><span style="background-color:#ffffff"><span style="color:#000000"><span style="background-color:#282a36"><code class="language-python"><span style="color:#ff79c6">import</span> osos<span style="color:#999999">.</span>getpid<span style="color:#999999">(</span><span style="color:#999999">)</span>
</code></span></span></span></span>

（2）獲取當(dāng)前父進(jìn)程編號：

<span style="color:rgba(0, 0, 0, 0.75)"><span style="background-color:#ffffff"><span style="color:#000000"><span style="background-color:#282a36"><code class="language-python"><span style="color:#ff79c6">import</span> osos<span style="color:#999999">.</span>getppid<span style="color:#999999">(</span><span style="color:#999999">)</span>
</code></span></span></span></span>

（3）例子：

<span style="color:rgba(0, 0, 0, 0.75)"><span style="background-color:#ffffff"><span style="color:#000000"><span style="background-color:#282a36"><code class="language-python"><span style="color:#6272a4"># 1.導(dǎo)入進(jìn)程包</span>
<span style="color:#ff79c6">import</span> os
<span style="color:#ff79c6">import</span> time
<span style="color:#ff79c6">import</span> multiprocessing<span style="color:#6272a4"># 唱歌</span>
<span style="color:#ff79c6">def</span> <span style="color:#8be9fd">sing</span><span style="color:#999999">(</span>num<span style="color:#999999">,</span> name<span style="color:#999999">)</span><span style="color:#999999">:</span><span style="color:#ff79c6">print</span><span style="color:#999999">(</span><span style="color:#f1fa8c">"唱歌進(jìn)程編號:"</span><span style="color:#999999">,</span> os<span style="color:#999999">.</span>getpid<span style="color:#999999">(</span><span style="color:#999999">)</span><span style="color:#999999">)</span><span style="color:#ff79c6">print</span><span style="color:#999999">(</span><span style="color:#f1fa8c">"唱歌進(jìn)程的父進(jìn)程:"</span><span style="color:#999999">,</span> os<span style="color:#999999">.</span>getppid<span style="color:#999999">(</span><span style="color:#999999">)</span><span style="color:#999999">)</span><span style="color:#ff79c6">for</span> i <span style="color:#ff79c6">in</span> <span style="color:#f1fa8c">range</span><span style="color:#999999">(</span>num<span style="color:#999999">)</span><span style="color:#999999">:</span><span style="color:#ff79c6">print</span><span style="color:#999999">(</span>name<span style="color:#999999">)</span><span style="color:#ff79c6">print</span><span style="color:#999999">(</span><span style="color:#f1fa8c">"唱歌..."</span><span style="color:#999999">)</span>time<span style="color:#999999">.</span>sleep<span style="color:#999999">(</span><span style="color:#f1fa8c">0.5</span><span style="color:#999999">)</span> <span style="color:#6272a4"># 延遲0.5秒</span><span style="color:#6272a4"># 跳舞</span>
<span style="color:#ff79c6">def</span> <span style="color:#8be9fd">dance</span><span style="color:#999999">(</span>num<span style="color:#999999">,</span> name<span style="color:#999999">)</span><span style="color:#999999">:</span><span style="color:#ff79c6">print</span><span style="color:#999999">(</span><span style="color:#f1fa8c">"跳舞進(jìn)程編號:"</span><span style="color:#999999">,</span> os<span style="color:#999999">.</span>getpid<span style="color:#999999">(</span><span style="color:#999999">)</span><span style="color:#999999">)</span><span style="color:#ff79c6">print</span><span style="color:#999999">(</span><span style="color:#f1fa8c">"跳舞進(jìn)程的父進(jìn)程:"</span><span style="color:#999999">,</span> os<span style="color:#999999">.</span>getppid<span style="color:#999999">(</span><span style="color:#999999">)</span><span style="color:#999999">)</span><span style="color:#ff79c6">for</span> i <span style="color:#ff79c6">in</span> <span style="color:#f1fa8c">range</span><span style="color:#999999">(</span>num<span style="color:#999999">)</span><span style="color:#999999">:</span><span style="color:#ff79c6">print</span><span style="color:#999999">(</span>name<span style="color:#999999">)</span><span style="color:#ff79c6">print</span><span style="color:#999999">(</span><span style="color:#f1fa8c">"跳舞..."</span><span style="color:#999999">)</span>time<span style="color:#999999">.</span>sleep<span style="color:#999999">(</span><span style="color:#f1fa8c">0.5</span><span style="color:#999999">)</span><span style="color:#ff79c6">if</span> __name__ <span style="color:#6272a4">==</span> <span style="color:#f1fa8c">"__main__"</span><span style="color:#999999">:</span><span style="color:#ff79c6">print</span><span style="color:#999999">(</span><span style="color:#f1fa8c">"主進(jìn)程的編號:"</span><span style="color:#999999">,</span> os<span style="color:#999999">.</span>getpid<span style="color:#999999">(</span><span style="color:#999999">)</span><span style="color:#999999">)</span><span style="color:#6272a4"># 2.使用進(jìn)程類創(chuàng)建進(jìn)程對象</span><span style="color:#6272a4"># args:使用元組方式給指定任務(wù)傳參</span>sing_process <span style="color:#6272a4">=</span> multiprocessing<span style="color:#999999">.</span>Process<span style="color:#999999">(</span>target<span style="color:#6272a4">=</span>sing<span style="color:#999999">,</span> args<span style="color:#6272a4">=</span><span style="color:#999999">(</span><span style="color:#f1fa8c">3</span><span style="color:#999999">,</span> <span style="color:#f1fa8c">"李華"</span><span style="color:#999999">)</span><span style="color:#999999">)</span><span style="color:#6272a4"># kwargs:使用字典方式給指定任務(wù)傳參</span>dance_process <span style="color:#6272a4">=</span> multiprocessing<span style="color:#999999">.</span>Process<span style="color:#999999">(</span>target<span style="color:#6272a4">=</span>dance<span style="color:#999999">,</span> kwargs<span style="color:#6272a4">=</span><span style="color:#999999">{</span><span style="color:#f1fa8c">"num"</span><span style="color:#999999">:</span> <span style="color:#f1fa8c">2</span><span style="color:#999999">,</span> <span style="color:#f1fa8c">"name"</span><span style="color:#999999">:</span><span style="color:#f1fa8c">"小明"</span><span style="color:#999999">}</span><span style="color:#999999">)</span><span style="color:#6272a4"># 3.使用進(jìn)程對象啟動進(jìn)程執(zhí)行指定任務(wù)</span>sing_process<span style="color:#999999">.</span>start<span style="color:#999999">(</span><span style="color:#999999">)</span>dance_process<span style="color:#999999">.</span>start<span style="color:#999999">(</span><span style="color:#999999">)</span>
</code></span></span></span></span>

運行結(jié)果：
在這里插入圖片描述

2.6 進(jìn)程的注意事項：

（1）主進(jìn)程會等待所有的子進(jìn)程完成才結(jié)束：

如下圖所示，打開QQ時會創(chuàng)建一個主進(jìn)程，而QQ里面有兩個子進(jìn)程。主進(jìn)程會等待所有的子進(jìn)程完成才結(jié)束：

在這里插入圖片描述

下面看一個例子：

<span style="color:rgba(0, 0, 0, 0.75)"><span style="background-color:#ffffff"><span style="color:#000000"><span style="background-color:#282a36"><code class="language-python"><span style="color:#ff79c6">import</span> time
<span style="color:#ff79c6">import</span> multiprocessing<span style="color:#ff79c6">def</span> <span style="color:#8be9fd">work</span><span style="color:#999999">(</span><span style="color:#999999">)</span><span style="color:#999999">:</span><span style="color:#6272a4"># 子進(jìn)程會工作2秒鐘</span><span style="color:#ff79c6">for</span> i <span style="color:#ff79c6">in</span> <span style="color:#f1fa8c">range</span><span style="color:#999999">(</span><span style="color:#f1fa8c">10</span><span style="color:#999999">)</span><span style="color:#999999">:</span><span style="color:#ff79c6">print</span><span style="color:#999999">(</span><span style="color:#f1fa8c">"工作中..."</span><span style="color:#999999">)</span>time<span style="color:#999999">.</span>sleep<span style="color:#999999">(</span><span style="color:#f1fa8c">0.2</span><span style="color:#999999">)</span><span style="color:#ff79c6">if</span> __name__ <span style="color:#6272a4">==</span> <span style="color:#f1fa8c">"__main__"</span><span style="color:#999999">:</span>work_process <span style="color:#6272a4">=</span> multiprocessing<span style="color:#999999">.</span>Process<span style="color:#999999">(</span>target<span style="color:#6272a4">=</span>work<span style="color:#999999">)</span>work_process<span style="color:#999999">.</span>start<span style="color:#999999">(</span><span style="color:#999999">)</span><span style="color:#6272a4"># 主進(jìn)程睡眠1秒</span>time<span style="color:#999999">.</span>sleep<span style="color:#999999">(</span><span style="color:#f1fa8c">1</span><span style="color:#999999">)</span><span style="color:#ff79c6">print</span><span style="color:#999999">(</span><span style="color:#f1fa8c">"主進(jìn)程執(zhí)行完了..."</span><span style="color:#999999">)</span>
</code></span></span></span></span>

運行結(jié)果：
在這里插入圖片描述

我們發(fā)現(xiàn)，雖然打印了主進(jìn)程執(zhí)行完了，但是程序還沒有結(jié)束，這就說明：主進(jìn)程會等待所有的子進(jìn)程完成才結(jié)束。

但是我們都知道，當(dāng)我們把QQ的主進(jìn)程關(guān)閉時，子進(jìn)程都結(jié)束了。那怎么做才能當(dāng)主進(jìn)程結(jié)束時，子進(jìn)程也結(jié)束了呢？

（2）設(shè)置守護(hù)主進(jìn)程：

這個就是說，每一個子進(jìn)程都守護(hù)主進(jìn)程，當(dāng)主進(jìn)程結(jié)束了之后，子進(jìn)程直接結(jié)束，也就是被銷毀。

只需要加一句話：

<span style="color:rgba(0, 0, 0, 0.75)"><span style="background-color:#ffffff"><span style="color:#000000"><span style="background-color:#282a36"><code class="language-python">work_process<span style="color:#999999">.</span>daemon <span style="color:#6272a4">=</span> <span style="color:#8be9fd">True</span> <span style="color:#6272a4"># 設(shè)置子進(jìn)程 守護(hù) 主進(jìn)程</span>
</code></span></span></span></span>

看個完整的例子：

<span style="color:rgba(0, 0, 0, 0.75)"><span style="background-color:#ffffff"><span style="color:#000000"><span style="background-color:#282a36"><code class="language-python"><span style="color:#ff79c6">import</span> time
<span style="color:#ff79c6">import</span> multiprocessing<span style="color:#ff79c6">def</span> <span style="color:#8be9fd">work</span><span style="color:#999999">(</span><span style="color:#999999">)</span><span style="color:#999999">:</span><span style="color:#6272a4"># 子進(jìn)程會工作2秒鐘</span><span style="color:#ff79c6">for</span> i <span style="color:#ff79c6">in</span> <span style="color:#f1fa8c">range</span><span style="color:#999999">(</span><span style="color:#f1fa8c">10</span><span style="color:#999999">)</span><span style="color:#999999">:</span><span style="color:#ff79c6">print</span><span style="color:#999999">(</span><span style="color:#f1fa8c">"工作中..."</span><span style="color:#999999">)</span>time<span style="color:#999999">.</span>sleep<span style="color:#999999">(</span><span style="color:#f1fa8c">0.2</span><span style="color:#999999">)</span><span style="color:#ff79c6">if</span> __name__ <span style="color:#6272a4">==</span> <span style="color:#f1fa8c">"__main__"</span><span style="color:#999999">:</span>work_process <span style="color:#6272a4">=</span> multiprocessing<span style="color:#999999">.</span>Process<span style="color:#999999">(</span>target<span style="color:#6272a4">=</span>work<span style="color:#999999">)</span>work_process<span style="color:#999999">.</span>daemon <span style="color:#6272a4">=</span> <span style="color:#8be9fd">True</span> <span style="color:#6272a4"># 設(shè)置子進(jìn)程 守護(hù) 主進(jìn)程</span>work_process<span style="color:#999999">.</span>start<span style="color:#999999">(</span><span style="color:#999999">)</span><span style="color:#6272a4"># 主進(jìn)程睡眠1秒</span>time<span style="color:#999999">.</span>sleep<span style="color:#999999">(</span><span style="color:#f1fa8c">1</span><span style="color:#999999">)</span><span style="color:#ff79c6">print</span><span style="color:#999999">(</span><span style="color:#f1fa8c">"主進(jìn)程執(zhí)行完了..."</span><span style="color:#999999">)</span>
</code></span></span></span></span>

運行結(jié)果：
在這里插入圖片描述

<span style="color:rgba(0, 0, 0, 0.75)"><span style="background-color:#ffffff"><span style="color:#000000"><span style="background-color:#282a36"><code class="language-python"><span style="color:#ff79c6">import</span> os
<span style="color:#ff79c6">import</span> multiprocessing<span style="color:#ff79c6">def</span> <span style="color:#8be9fd">copy_file</span><span style="color:#999999">(</span>file_name<span style="color:#999999">,</span> source_dir<span style="color:#999999">,</span> dest_dir<span style="color:#999999">)</span><span style="color:#999999">:</span><span style="color:#6272a4"># 1.拼接源文件路徑和目標(biāo)文件路徑</span>source_path <span style="color:#6272a4">=</span> source_dir <span style="color:#6272a4">+</span> <span style="color:#f1fa8c">"/"</span> <span style="color:#6272a4">+</span> file_namedest_path <span style="color:#6272a4">=</span> dest_dir <span style="color:#6272a4">+</span> <span style="color:#f1fa8c">"/"</span> <span style="color:#6272a4">+</span> file_name<span style="color:#6272a4"># 2.打開源文件和目標(biāo)文件</span><span style="color:#ff79c6">with</span> <span style="color:#f1fa8c">open</span><span style="color:#999999">(</span>source_path<span style="color:#999999">,</span> <span style="color:#f1fa8c">"rb"</span><span style="color:#999999">)</span> <span style="color:#ff79c6">as</span> source_file<span style="color:#999999">:</span><span style="color:#ff79c6">with</span> <span style="color:#f1fa8c">open</span><span style="color:#999999">(</span>dest_path<span style="color:#999999">,</span> <span style="color:#f1fa8c">"wb"</span><span style="color:#999999">)</span> <span style="color:#ff79c6">as</span> dest_file<span style="color:#999999">:</span><span style="color:#6272a4"># 3.循環(huán)讀取源文件到目標(biāo)文件</span><span style="color:#ff79c6">while</span> <span style="color:#8be9fd">True</span><span style="color:#999999">:</span>data <span style="color:#6272a4">=</span> source_file<span style="color:#999999">.</span>read<span style="color:#999999">(</span><span style="color:#f1fa8c">1024</span><span style="color:#999999">)</span><span style="color:#ff79c6">if</span> data<span style="color:#999999">:</span> <span style="color:#6272a4"># 沒到文件的最后一行</span>dest_file<span style="color:#999999">.</span>write<span style="color:#999999">(</span>data<span style="color:#999999">)</span><span style="color:#ff79c6">else</span><span style="color:#999999">:</span> <span style="color:#6272a4"># 為空，則說明到最后一行</span><span style="color:#ff79c6">break</span><span style="color:#ff79c6">if</span> __name__ <span style="color:#6272a4">==</span> <span style="color:#f1fa8c">"__main__"</span><span style="color:#999999">:</span><span style="color:#6272a4"># 1.定義源文件夾和目標(biāo)文件夾</span>source_dir <span style="color:#6272a4">=</span> r<span style="color:#f1fa8c">"python視頻"</span>dest_dir <span style="color:#6272a4">=</span> r<span style="color:#f1fa8c">"/home/python/桌面/test"</span><span style="color:#6272a4"># 2.創(chuàng)建目標(biāo)文件夾</span><span style="color:#ff79c6">try</span><span style="color:#999999">:</span>os<span style="color:#999999">.</span>mkdir<span style="color:#999999">(</span>dest_dir<span style="color:#999999">)</span><span style="color:#ff79c6">except</span><span style="color:#999999">:</span><span style="color:#ff79c6">print</span><span style="color:#999999">(</span><span style="color:#f1fa8c">"目標(biāo)文件夾已經(jīng)存在，未創(chuàng)建"</span><span style="color:#999999">)</span><span style="color:#6272a4"># 3.讀取源文件的文件列表</span>file_list <span style="color:#6272a4">=</span> os<span style="color:#999999">.</span>listdir<span style="color:#999999">(</span>source_dir<span style="color:#999999">)</span><span style="color:#6272a4"># 4.遍歷文件列表實現(xiàn)拷貝</span><span style="color:#ff79c6">for</span> file_name <span style="color:#ff79c6">in</span> file_list<span style="color:#999999">:</span><span style="color:#6272a4"># copy_file(file_name, source_dir,dest_dir) # 這個實現(xiàn)是單任務(wù)的拷貝</span><span style="color:#6272a4"># 5.使用多進(jìn)程實現(xiàn)多任務(wù)拷貝</span>sub_process <span style="color:#6272a4">=</span> multiprocessing<span style="color:#999999">.</span>Process<span style="color:#999999">(</span>target<span style="color:#6272a4">=</span>copy_file<span style="color:#999999">,</span>args<span style="color:#6272a4">=</span><span style="color:#999999">(</span>file_name<span style="color:#999999">,</span> source_dir<span style="color:#999999">,</span> dest_dir<span style="color:#999999">)</span><span style="color:#999999">)</span>sub_process<span style="color:#999999">.</span>start<span style="color:#999999">(</span><span style="color:#999999">)</span>
</code></span></span></span></span>

三、線程：

3.1 線程的介紹：

進(jìn)程是分配資源的最小單位，一旦創(chuàng)建一個進(jìn)程就會分配一定的資源，就像跟兩個人聊QQ就需要打開兩個QQ軟件一樣是比較浪費資源的。
線程是程序執(zhí)行的最小單位，實際上進(jìn)程只負(fù)責(zé)分配資源，而利用這些資源執(zhí)行程序的是線程，也就說進(jìn)程是線程的容器。一個進(jìn)程中最少有一一個線程來負(fù)責(zé)執(zhí)行程序，同時線程自己不擁有系統(tǒng)資源，只需要一點兒在運行中必不可少的資源，但它可與同屬一個進(jìn)程的其它線程共享進(jìn)程所擁有的全部資源。這就像通過一個QQ軟件(一個進(jìn)程)打開兩個窗口(兩個線程)跟兩個人聊天一樣，實現(xiàn)多任務(wù)的同時也節(jié)省了資源。

3.2?多線程的作用：

在這里插入圖片描述

將上圖中的程序使用多線程實現(xiàn)，怎么做呢？為此我們先看一下，單線程是怎么實現(xiàn)的：
如下圖，單線程是按照順序?qū)崿F(xiàn)的，也就是說進(jìn)程中默認(rèn)有一個線程用來執(zhí)行程序，我們稱之為主線程。

在這里插入圖片描述

如何使用多線程實現(xiàn)呢？和前面的進(jìn)程一樣，用主線程執(zhí)行func_a，再創(chuàng)建一個子線程執(zhí)行func_b。

在這里插入圖片描述

3.3 多線程實現(xiàn)多任務(wù)：

（1）線程的創(chuàng)建步驟：

1、導(dǎo)入線程包：

<span style="color:rgba(0, 0, 0, 0.75)"><span style="background-color:#ffffff"><span style="color:#000000"><span style="background-color:#282a36"><code class="language-python"><span style="color:#ff79c6">import</span> threading
</code></span></span></span></span>

2、通過線程類創(chuàng)建線程對象：

<span style="color:rgba(0, 0, 0, 0.75)"><span style="background-color:#ffffff"><span style="color:#000000"><span style="background-color:#282a36"><code class="language-python">線程對象 <span style="color:#6272a4">=</span> threading<span style="color:#999999">.</span>Thread<span style="color:#999999">(</span>target<span style="color:#6272a4">=</span>任務(wù)名<span style="color:#999999">)</span>
</code></span></span></span></span>

在這里插入圖片描述

3、啟動線程執(zhí)行任務(wù)：

<span style="color:rgba(0, 0, 0, 0.75)"><span style="background-color:#ffffff"><span style="color:#000000"><span style="background-color:#282a36"><code class="language-python">線程對象<span style="color:#999999">.</span>start<span style="color:#999999">(</span><span style="color:#999999">)</span>
</code></span></span></span></span>

（2）多進(jìn)程例子：

下面程序是單線程，先執(zhí)行唱歌的函數(shù)，再執(zhí)行跳舞的函數(shù)。需要3秒完成。

<span style="color:rgba(0, 0, 0, 0.75)"><span style="background-color:#ffffff"><span style="color:#000000"><span style="background-color:#282a36"><code class="language-python"><span style="color:#ff79c6">import</span> time<span style="color:#6272a4"># 唱歌</span>
<span style="color:#ff79c6">def</span> <span style="color:#8be9fd">sing</span><span style="color:#999999">(</span><span style="color:#999999">)</span><span style="color:#999999">:</span><span style="color:#ff79c6">for</span> i <span style="color:#ff79c6">in</span> <span style="color:#f1fa8c">range</span><span style="color:#999999">(</span><span style="color:#f1fa8c">3</span><span style="color:#999999">)</span><span style="color:#999999">:</span><span style="color:#ff79c6">print</span><span style="color:#999999">(</span><span style="color:#f1fa8c">"唱歌..."</span><span style="color:#999999">)</span>time<span style="color:#999999">.</span>sleep<span style="color:#999999">(</span><span style="color:#f1fa8c">0.5</span><span style="color:#999999">)</span> <span style="color:#6272a4"># 延遲0.5秒</span>
<span style="color:#6272a4"># 跳舞</span>
<span style="color:#ff79c6">def</span> <span style="color:#8be9fd">dance</span><span style="color:#999999">(</span><span style="color:#999999">)</span><span style="color:#999999">:</span><span style="color:#ff79c6">for</span> i <span style="color:#ff79c6">in</span> <span style="color:#f1fa8c">range</span><span style="color:#999999">(</span><span style="color:#f1fa8c">3</span><span style="color:#999999">)</span><span style="color:#999999">:</span><span style="color:#ff79c6">print</span><span style="color:#999999">(</span><span style="color:#f1fa8c">"跳舞..."</span><span style="color:#999999">)</span>time<span style="color:#999999">.</span>sleep<span style="color:#999999">(</span><span style="color:#f1fa8c">0.5</span><span style="color:#999999">)</span>
<span style="color:#ff79c6">if</span> __name__ <span style="color:#6272a4">==</span> <span style="color:#f1fa8c">"__main__"</span><span style="color:#999999">:</span>sing<span style="color:#999999">(</span><span style="color:#999999">)</span>dance<span style="color:#999999">(</span><span style="color:#999999">)</span>
</code></span></span></span></span>

運行結(jié)果：
在這里插入圖片描述

上面的程序怎么使用多線程實現(xiàn)呢？下面的程序?qū)崿F(xiàn)了多線程實現(xiàn)多任務(wù)，我們會發(fā)現(xiàn)，只需要1.5秒執(zhí)行完了，唱歌和跳舞是交替執(zhí)行的。

<span style="color:rgba(0, 0, 0, 0.75)"><span style="background-color:#ffffff"><span style="color:#000000"><span style="background-color:#282a36"><code class="language-python"><span style="color:#6272a4"># 1.導(dǎo)入進(jìn)程包</span>
<span style="color:#ff79c6">import</span> time
<span style="color:#ff79c6">import</span> threading<span style="color:#6272a4"># 唱歌</span>
<span style="color:#ff79c6">def</span> <span style="color:#8be9fd">sing</span><span style="color:#999999">(</span><span style="color:#999999">)</span><span style="color:#999999">:</span><span style="color:#ff79c6">for</span> i <span style="color:#ff79c6">in</span> <span style="color:#f1fa8c">range</span><span style="color:#999999">(</span><span style="color:#f1fa8c">3</span><span style="color:#999999">)</span><span style="color:#999999">:</span><span style="color:#ff79c6">print</span><span style="color:#999999">(</span><span style="color:#f1fa8c">"唱歌..."</span><span style="color:#999999">)</span>time<span style="color:#999999">.</span>sleep<span style="color:#999999">(</span><span style="color:#f1fa8c">0.5</span><span style="color:#999999">)</span> <span style="color:#6272a4"># 延遲0.5秒</span><span style="color:#6272a4"># 跳舞</span>
<span style="color:#ff79c6">def</span> <span style="color:#8be9fd">dance</span><span style="color:#999999">(</span><span style="color:#999999">)</span><span style="color:#999999">:</span><span style="color:#ff79c6">for</span> i <span style="color:#ff79c6">in</span> <span style="color:#f1fa8c">range</span><span style="color:#999999">(</span><span style="color:#f1fa8c">3</span><span style="color:#999999">)</span><span style="color:#999999">:</span><span style="color:#ff79c6">print</span><span style="color:#999999">(</span><span style="color:#f1fa8c">"跳舞..."</span><span style="color:#999999">)</span>time<span style="color:#999999">.</span>sleep<span style="color:#999999">(</span><span style="color:#f1fa8c">0.5</span><span style="color:#999999">)</span><span style="color:#ff79c6">if</span> __name__ <span style="color:#6272a4">==</span> <span style="color:#f1fa8c">"__main__"</span><span style="color:#999999">:</span><span style="color:#6272a4"># 2.使用進(jìn)程類創(chuàng)建進(jìn)程對象</span>sing_thread <span style="color:#6272a4">=</span> threading<span style="color:#999999">.</span>Thread<span style="color:#999999">(</span>target<span style="color:#6272a4">=</span>sing<span style="color:#999999">)</span>dance_thread <span style="color:#6272a4">=</span> threading<span style="color:#999999">.</span>Thread<span style="color:#999999">(</span>target<span style="color:#6272a4">=</span>dance<span style="color:#999999">)</span><span style="color:#6272a4"># 3.使用進(jìn)程對象啟動進(jìn)程執(zhí)行指定任務(wù)</span>sing_thread<span style="color:#999999">.</span>start<span style="color:#999999">(</span><span style="color:#999999">)</span>dance_thread<span style="color:#999999">.</span>start<span style="color:#999999">(</span><span style="color:#999999">)</span>
</code></span></span></span></span>

運行結(jié)果：
在這里插入圖片描述

3.4 線程執(zhí)行帶有參數(shù)的任務(wù)：

（1）參數(shù)說明：

<span style="color:rgba(0, 0, 0, 0.75)"><span style="background-color:#ffffff"><span style="color:#000000"><span style="background-color:#282a36"><code class="language-python">進(jìn)程對象 <span style="color:#6272a4">=</span> threading<span style="color:#999999">.</span>Thread<span style="color:#999999">(</span>target<span style="color:#6272a4">=</span>任務(wù)名<span style="color:#999999">,</span> args<span style="color:#999999">,</span> kwargs<span style="color:#999999">)</span>
</code></span></span></span></span>

在這里插入圖片描述

（2）例子：

<span style="color:rgba(0, 0, 0, 0.75)"><span style="background-color:#ffffff"><span style="color:#000000"><span style="background-color:#282a36"><code class="language-python"><span style="color:#6272a4"># 1.導(dǎo)入進(jìn)程包</span>
<span style="color:#ff79c6">import</span> time
<span style="color:#ff79c6">import</span> threading<span style="color:#6272a4"># 唱歌</span>
<span style="color:#ff79c6">def</span> <span style="color:#8be9fd">sing</span><span style="color:#999999">(</span>num<span style="color:#999999">,</span> name<span style="color:#999999">)</span><span style="color:#999999">:</span><span style="color:#ff79c6">for</span> i <span style="color:#ff79c6">in</span> <span style="color:#f1fa8c">range</span><span style="color:#999999">(</span>num<span style="color:#999999">)</span><span style="color:#999999">:</span><span style="color:#ff79c6">print</span><span style="color:#999999">(</span>name<span style="color:#999999">)</span><span style="color:#ff79c6">print</span><span style="color:#999999">(</span><span style="color:#f1fa8c">"唱歌..."</span><span style="color:#999999">)</span>time<span style="color:#999999">.</span>sleep<span style="color:#999999">(</span><span style="color:#f1fa8c">0.5</span><span style="color:#999999">)</span> <span style="color:#6272a4"># 延遲0.5秒</span><span style="color:#6272a4"># 跳舞</span>
<span style="color:#ff79c6">def</span> <span style="color:#8be9fd">dance</span><span style="color:#999999">(</span>num<span style="color:#999999">,</span> name<span style="color:#999999">)</span><span style="color:#999999">:</span><span style="color:#ff79c6">for</span> i <span style="color:#ff79c6">in</span> <span style="color:#f1fa8c">range</span><span style="color:#999999">(</span>num<span style="color:#999999">)</span><span style="color:#999999">:</span><span style="color:#ff79c6">print</span><span style="color:#999999">(</span>name<span style="color:#999999">)</span><span style="color:#ff79c6">print</span><span style="color:#999999">(</span><span style="color:#f1fa8c">"跳舞..."</span><span style="color:#999999">)</span>time<span style="color:#999999">.</span>sleep<span style="color:#999999">(</span><span style="color:#f1fa8c">0.5</span><span style="color:#999999">)</span><span style="color:#ff79c6">if</span> __name__ <span style="color:#6272a4">==</span> <span style="color:#f1fa8c">"__main__"</span><span style="color:#999999">:</span><span style="color:#6272a4"># 2.使用進(jìn)程類創(chuàng)建進(jìn)程對象</span><span style="color:#6272a4"># args:使用元組方式給指定任務(wù)傳參</span>sing_thread <span style="color:#6272a4">=</span> threading<span style="color:#999999">.</span>Thread<span style="color:#999999">(</span>target<span style="color:#6272a4">=</span>sing<span style="color:#999999">,</span> args<span style="color:#6272a4">=</span><span style="color:#999999">(</span><span style="color:#f1fa8c">3</span><span style="color:#999999">,</span> <span style="color:#f1fa8c">"李華"</span><span style="color:#999999">)</span><span style="color:#999999">)</span><span style="color:#6272a4"># kwargs:使用字典方式給指定任務(wù)傳參</span>dance_thread <span style="color:#6272a4">=</span> threading<span style="color:#999999">.</span>Thread<span style="color:#999999">(</span>target<span style="color:#6272a4">=</span>dance<span style="color:#999999">,</span> kwargs<span style="color:#6272a4">=</span><span style="color:#999999">{</span><span style="color:#f1fa8c">"num"</span><span style="color:#999999">:</span> <span style="color:#f1fa8c">2</span><span style="color:#999999">,</span> <span style="color:#f1fa8c">"name"</span><span style="color:#999999">:</span><span style="color:#f1fa8c">"小明"</span><span style="color:#999999">}</span><span style="color:#999999">)</span><span style="color:#6272a4"># 3.使用進(jìn)程對象啟動進(jìn)程執(zhí)行指定任務(wù)</span>sing_thread<span style="color:#999999">.</span>start<span style="color:#999999">(</span><span style="color:#999999">)</span>dance_thread<span style="color:#999999">.</span>start<span style="color:#999999">(</span><span style="color:#999999">)</span>
</code></span></span></span></span>

3.5 主線程和子線程的結(jié)束順序：

（1）主線程會等待所有的子線程完成才結(jié)束：

下面的例子說明了主線程會等待所有的子線程完成才結(jié)束。

<span style="color:rgba(0, 0, 0, 0.75)"><span style="background-color:#ffffff"><span style="color:#000000"><span style="background-color:#282a36"><code class="language-python"><span style="color:#ff79c6">import</span> time
<span style="color:#ff79c6">import</span> threading<span style="color:#ff79c6">def</span> <span style="color:#8be9fd">work</span><span style="color:#999999">(</span><span style="color:#999999">)</span><span style="color:#999999">:</span><span style="color:#6272a4"># 子進(jìn)程會工作2秒鐘</span><span style="color:#ff79c6">for</span> i <span style="color:#ff79c6">in</span> <span style="color:#f1fa8c">range</span><span style="color:#999999">(</span><span style="color:#f1fa8c">10</span><span style="color:#999999">)</span><span style="color:#999999">:</span><span style="color:#ff79c6">print</span><span style="color:#999999">(</span><span style="color:#f1fa8c">"工作中..."</span><span style="color:#999999">)</span>time<span style="color:#999999">.</span>sleep<span style="color:#999999">(</span><span style="color:#f1fa8c">0.2</span><span style="color:#999999">)</span><span style="color:#ff79c6">if</span> __name__ <span style="color:#6272a4">==</span> <span style="color:#f1fa8c">"__main__"</span><span style="color:#999999">:</span>work_thread <span style="color:#6272a4">=</span> threading<span style="color:#999999">.</span>Thread<span style="color:#999999">(</span>target<span style="color:#6272a4">=</span>work<span style="color:#999999">)</span>work_thread<span style="color:#999999">.</span>start<span style="color:#999999">(</span><span style="color:#999999">)</span><span style="color:#6272a4"># 主進(jìn)程睡眠1秒</span>time<span style="color:#999999">.</span>sleep<span style="color:#999999">(</span><span style="color:#f1fa8c">1</span><span style="color:#999999">)</span><span style="color:#ff79c6">print</span><span style="color:#999999">(</span><span style="color:#f1fa8c">"主線程執(zhí)行完了..."</span><span style="color:#999999">)</span>
</code></span></span></span></span>

運行結(jié)果：
在這里插入圖片描述

我們發(fā)現(xiàn)，雖然打印了主線程執(zhí)行完了，但是程序還沒有結(jié)束，這就說明：主線程會等待所有的子線程完成才結(jié)束。

但是我們希望主線程結(jié)束了，則所有的子線程都結(jié)束，那怎么做呢？接著看：

（2）設(shè)置守護(hù)主線程：

方法一：
只需要加一句話：

<span style="color:rgba(0, 0, 0, 0.75)"><span style="background-color:#ffffff"><span style="color:#000000"><span style="background-color:#282a36"><code class="language-python">work_process<span style="color:#999999">.</span>daemon <span style="color:#6272a4">=</span> <span style="color:#8be9fd">True</span> <span style="color:#6272a4"># 設(shè)置子線程 守護(hù) 主進(jìn)程</span>
</code></span></span></span></span>

方法二：

<span style="color:rgba(0, 0, 0, 0.75)"><span style="background-color:#ffffff"><span style="color:#000000"><span style="background-color:#282a36"><code class="language-python">work_thread <span style="color:#6272a4">=</span> threading<span style="color:#999999">.</span>Thread<span style="color:#999999">(</span>target<span style="color:#6272a4">=</span>work<span style="color:#999999">,</span> daemon<span style="color:#6272a4">=</span><span style="color:#8be9fd">True</span><span style="color:#999999">)</span> <span style="color:#6272a4"># 設(shè)置子線程 守護(hù) 主進(jìn)程</span>
</code></span></span></span></span>

看個完整的例子：

<span style="color:rgba(0, 0, 0, 0.75)"><span style="background-color:#ffffff"><span style="color:#000000"><span style="background-color:#282a36"><code class="language-python"><span style="color:#ff79c6">import</span> time
<span style="color:#ff79c6">import</span> threading<span style="color:#ff79c6">def</span> <span style="color:#8be9fd">work</span><span style="color:#999999">(</span><span style="color:#999999">)</span><span style="color:#999999">:</span><span style="color:#6272a4"># 子進(jìn)程會工作2秒鐘</span><span style="color:#ff79c6">for</span> i <span style="color:#ff79c6">in</span> <span style="color:#f1fa8c">range</span><span style="color:#999999">(</span><span style="color:#f1fa8c">10</span><span style="color:#999999">)</span><span style="color:#999999">:</span><span style="color:#ff79c6">print</span><span style="color:#999999">(</span><span style="color:#f1fa8c">"工作中..."</span><span style="color:#999999">)</span>time<span style="color:#999999">.</span>sleep<span style="color:#999999">(</span><span style="color:#f1fa8c">0.2</span><span style="color:#999999">)</span><span style="color:#ff79c6">if</span> __name__ <span style="color:#6272a4">==</span> <span style="color:#f1fa8c">"__main__"</span><span style="color:#999999">:</span><span style="color:#6272a4"># 方法一：</span>work_thread <span style="color:#6272a4">=</span> threading<span style="color:#999999">.</span>Thread<span style="color:#999999">(</span>target<span style="color:#6272a4">=</span>work<span style="color:#999999">,</span> daemon<span style="color:#6272a4">=</span><span style="color:#8be9fd">True</span><span style="color:#999999">)</span> <span style="color:#6272a4"># 設(shè)置子進(jìn)程 守護(hù) 主進(jìn)程</span><span style="color:#6272a4"># 方法二：</span>work_thread<span style="color:#999999">.</span>daemon <span style="color:#6272a4">=</span> <span style="color:#8be9fd">True</span> <span style="color:#6272a4"># 設(shè)置子進(jìn)程 守護(hù) 主進(jìn)程</span>work_thread<span style="color:#999999">.</span>start<span style="color:#999999">(</span><span style="color:#999999">)</span><span style="color:#6272a4"># 主進(jìn)程睡眠1秒</span>time<span style="color:#999999">.</span>sleep<span style="color:#999999">(</span><span style="color:#f1fa8c">1</span><span style="color:#999999">)</span><span style="color:#ff79c6">print</span><span style="color:#999999">(</span><span style="color:#f1fa8c">"主線程執(zhí)行完了..."</span><span style="color:#999999">)</span>
</code></span></span></span></span>

運行結(jié)果：
在這里插入圖片描述

3.6 線程間的執(zhí)行順序：

（1）線程間的執(zhí)行是無序的：

下圖是一個進(jìn)程創(chuàng)建的三個線程，這三個線程的執(zhí)行順序是無序的，與創(chuàng)建的順序無關(guān)，它與操作系統(tǒng)的調(diào)度有關(guān)。

在這里插入圖片描述
看一個例子：

（2）例子：

我們發(fā)現(xiàn)，運行的結(jié)果和線程的創(chuàng)建順序并不一樣，所以證明：線程間的執(zhí)行是無序的。

<span style="color:rgba(0, 0, 0, 0.75)"><span style="background-color:#ffffff"><span style="color:#000000"><span style="background-color:#282a36"><code class="language-python"><span style="color:#ff79c6">import</span> threading
<span style="color:#ff79c6">import</span> time<span style="color:#ff79c6">def</span> <span style="color:#8be9fd">task</span><span style="color:#999999">(</span><span style="color:#999999">)</span><span style="color:#999999">:</span>time<span style="color:#999999">.</span>sleep<span style="color:#999999">(</span><span style="color:#f1fa8c">1</span><span style="color:#999999">)</span> <span style="color:#6272a4"># 延遲一秒</span><span style="color:#6272a4"># current_thread:獲取當(dāng)前線程的對象</span>thread <span style="color:#6272a4">=</span> threading<span style="color:#999999">.</span>current_thread<span style="color:#999999">(</span><span style="color:#999999">)</span> <span style="color:#6272a4"># 獲取當(dāng)前的線程</span><span style="color:#ff79c6">print</span><span style="color:#999999">(</span>thread<span style="color:#999999">)</span><span style="color:#ff79c6">if</span> __name__ <span style="color:#6272a4">==</span> <span style="color:#f1fa8c">"__main__"</span><span style="color:#999999">:</span><span style="color:#ff79c6">for</span> i <span style="color:#ff79c6">in</span> <span style="color:#f1fa8c">range</span><span style="color:#999999">(</span><span style="color:#f1fa8c">5</span><span style="color:#999999">)</span><span style="color:#999999">:</span> <span style="color:#6272a4"># 創(chuàng)建5個線程</span>sub_thread <span style="color:#6272a4">=</span> threading<span style="color:#999999">.</span>Thread<span style="color:#999999">(</span>target<span style="color:#6272a4">=</span>task<span style="color:#999999">)</span>sub_thread<span style="color:#999999">.</span>start<span style="color:#999999">(</span><span style="color:#999999">)</span>
</code></span></span></span></span>

運行結(jié)果：
在這里插入圖片描述

由于實現(xiàn)的步驟和多進(jìn)程是一樣的，所有接下來直接看代碼，注釋在代碼中：

<span style="color:rgba(0, 0, 0, 0.75)"><span style="background-color:#ffffff"><span style="color:#000000"><span style="background-color:#282a36"><code class="language-python"><span style="color:#ff79c6">import</span> os
<span style="color:#ff79c6">import</span> threading
<span style="color:#ff79c6">def</span> <span style="color:#8be9fd">copy_file</span><span style="color:#999999">(</span>file_name<span style="color:#999999">,</span> source_dir<span style="color:#999999">,</span> dest_dir<span style="color:#999999">)</span><span style="color:#999999">:</span><span style="color:#6272a4"># 1.拼接源文件路徑和目標(biāo)文件路徑</span>source_path <span style="color:#6272a4">=</span> source_dir <span style="color:#6272a4">+</span> <span style="color:#f1fa8c">"/"</span> <span style="color:#6272a4">+</span> file_namedest_path <span style="color:#6272a4">=</span> dest_dir <span style="color:#6272a4">+</span> <span style="color:#f1fa8c">"/"</span> <span style="color:#6272a4">+</span> file_name<span style="color:#6272a4"># 2.打開源文件和目標(biāo)文件</span><span style="color:#ff79c6">with</span> <span style="color:#f1fa8c">open</span><span style="color:#999999">(</span>source_path<span style="color:#999999">,</span> <span style="color:#f1fa8c">"rb"</span><span style="color:#999999">)</span> <span style="color:#ff79c6">as</span> source_file<span style="color:#999999">:</span><span style="color:#ff79c6">with</span> <span style="color:#f1fa8c">open</span><span style="color:#999999">(</span>dest_path<span style="color:#999999">,</span> <span style="color:#f1fa8c">"wb"</span><span style="color:#999999">)</span> <span style="color:#ff79c6">as</span> dest_file<span style="color:#999999">:</span><span style="color:#6272a4"># 3.循環(huán)讀取源文件到目標(biāo)文件</span><span style="color:#ff79c6">while</span> <span style="color:#8be9fd">True</span><span style="color:#999999">:</span>data <span style="color:#6272a4">=</span> source_file<span style="color:#999999">.</span>read<span style="color:#999999">(</span><span style="color:#f1fa8c">1024</span><span style="color:#999999">)</span><span style="color:#ff79c6">if</span> data<span style="color:#999999">:</span> <span style="color:#6272a4"># 沒到文件的最后一行</span>dest_file<span style="color:#999999">.</span>write<span style="color:#999999">(</span>data<span style="color:#999999">)</span><span style="color:#ff79c6">else</span><span style="color:#999999">:</span> <span style="color:#6272a4"># 為空，則說明到最后一行</span><span style="color:#ff79c6">break</span><span style="color:#ff79c6">if</span> __name__ <span style="color:#6272a4">==</span> <span style="color:#f1fa8c">"__main__"</span><span style="color:#999999">:</span><span style="color:#6272a4"># 1.定義源文件夾和目標(biāo)文件夾</span>source_dir <span style="color:#6272a4">=</span> r<span style="color:#f1fa8c">"python視頻"</span>dest_dir <span style="color:#6272a4">=</span> r<span style="color:#f1fa8c">"/home/python/桌面/test"</span><span style="color:#6272a4"># 2.創(chuàng)建目標(biāo)文件夾</span><span style="color:#ff79c6">try</span><span style="color:#999999">:</span>os<span style="color:#999999">.</span>mkdir<span style="color:#999999">(</span>dest_dir<span style="color:#999999">)</span><span style="color:#ff79c6">except</span><span style="color:#999999">:</span><span style="color:#ff79c6">print</span><span style="color:#999999">(</span><span style="color:#f1fa8c">"目標(biāo)文件夾已經(jīng)存在，未創(chuàng)建"</span><span style="color:#999999">)</span><span style="color:#6272a4"># 3.讀取源文件的文件列表</span>file_list <span style="color:#6272a4">=</span> os<span style="color:#999999">.</span>listdir<span style="color:#999999">(</span>source_dir<span style="color:#999999">)</span><span style="color:#6272a4"># 4.遍歷文件列表實現(xiàn)拷貝</span><span style="color:#ff79c6">for</span> file_name <span style="color:#ff79c6">in</span> file_list<span style="color:#999999">:</span><span style="color:#6272a4"># copy_file(file_name, source_dir,dest_dir) # 這個實現(xiàn)是單任務(wù)的拷貝</span><span style="color:#6272a4"># 5.使用多線程實現(xiàn)多任務(wù)拷貝</span>sub_thread <span style="color:#6272a4">=</span> threading<span style="color:#999999">.</span>Thread<span style="color:#999999">(</span>target<span style="color:#6272a4">=</span>copy_file<span style="color:#999999">,</span>args<span style="color:#6272a4">=</span><span style="color:#999999">(</span>file_name<span style="color:#999999">,</span> source_dir<span style="color:#999999">,</span> dest_dir<span style="color:#999999">)</span><span style="color:#999999">)</span>sub_thread<span style="color:#999999">.</span>start<span style="color:#999999">(</span><span style="color:#999999">)</span>
</code></span></span></span></span>

四、進(jìn)程和線程對比：

http://www.risenshineclean.com/news/57254.html

一、多任務(wù)

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一、多任務(wù)