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多线程与MySQL（十）

时间：2021-07-01 10:21:17 帮助过：15人阅读

threading import Thread,Lock,RLock import time # mutexA=Lock() # mutexB=Lock() mutexA=mutexB=RLock() #一个线程拿到锁，counter加1,该线程内又碰到加锁的情况，则counter继续加1，这期间所有其他线程都只能等待，等待该线程释放所有锁，即counter递减到0为止 class MyThread(Thread): def run(self): self.f1() self.f2() def f1(self): mutexA.acquire() print(‘%s 拿到了A锁‘ %self.name) mutexB.acquire() print(‘%s 拿到了B锁‘ % self.name) mutexB.release() #1 mutexA.release() #0 def f2(self): mutexB.acquire() print(‘%s 拿到了B锁‘ % self.name) time.sleep(0.1) mutexA.acquire() print(‘%s 拿到了A锁‘ % self.name) mutexA.release() mutexB.release() if __name__ == ‘__main__‘: for i in range(10): t=MyThread() t.start()

1.3 信号量Semaphore

同进程的一样，Semaphore管理一个内置的计数器，每当调用acquire()时内置计数器-1；调用release() 时内置计数器+1；计数器不能小于0；当计数器为0时，acquire()将阻塞线程直到其他线程调用release()。

实例：(同时只有5个线程可以获得semaphore,即可以限制最大连接数为5)：

<span style="color: #0000ff">from</span> threading <span style="color: #0000ff">import</span><span style="color: #000000"> Thread,Semaphore,current_thread
</span><span style="color: #0000ff">import</span><span style="color: #000000"> time,random
 
sm</span>=Semaphore(5<span style="color: #000000">)
 
</span><span style="color: #0000ff">def</span><span style="color: #000000"> task():
    with sm:
        </span><span style="color: #0000ff">print</span>(<span style="color: #800000">‘</span><span style="color: #800000">%s is laing</span><span style="color: #800000">‘</span> %<span style="color: #000000">current_thread().getName())
        time.sleep(random.randint(</span>1,3<span style="color: #000000">))
 
</span><span style="color: #0000ff">if</span> <span style="color: #800080">__name__</span> == <span style="color: #800000">‘</span><span style="color: #800000">__main__</span><span style="color: #800000">‘</span><span style="color: #000000">:
    </span><span style="color: #0000ff">for</span> i <span style="color: #0000ff">in</span> range(20<span style="color: #000000">):
        t</span>=Thread(target=<span style="color: #000000">task)
        t.start()</span>

与进程池是完全不同的概念，进程池Pool(4)，最大只能产生4个进程，而且从头到尾都只是这四个进程，不会产生新的，而信号量是产生一堆线程/进程

1.4 Event事件

同进程的一样，线程的一个关键特性是每个线程都是独立运行且状态不可预测。如果程序中的其他线程需要通过判断某个线程的状态来确定自己下一步的操作,这时线程同步问题就会变得非常棘手。为了解决这些问题,我们需要使用threading库中的Event对象。对象包含一个可由线程设置的信号标志,它允许线程等待某些事件的发生。在初始情况下,Event对象中的信号标志被设置为假。如果有线程等待一个Event对象, 而这个Event对象的标志为假,那么这个线程将会被一直阻塞直至该标志为真。一个线程如果将一个Event对象的信号标志设置为真,它将唤醒所有等待这个Event对象的线程。如果一个线程等待一个已经被设置为真的Event对象,那么它将忽略这个事件, 继续执行

<span style="color: #000000">event.isSet()：返回event的状态值；
 
event.wait()：如果 event.isSet()</span>==<span style="color: #000000">False将阻塞线程；
 
event.set()： 设置event的状态值为True，所有阻塞池的线程激活进入就绪状态， 等待操作系统调度；
 
event.clear()：恢复event的状态值为False。
 </span>

例如，有多个工作线程尝试链接MySQL，我们想要在链接前确保MySQL服务正常才让那些工作线程去连接MySQL服务器，如果连接不成功，都会去尝试重新连接。那么我们就可以采用threading.Event机制来协调各个工作线程的连接操作

<span style="color: #0000ff">from</span> threading <span style="color: #0000ff">import</span><span style="color: #000000"> Thread,Event,current_thread
</span><span style="color: #0000ff">import</span><span style="color: #000000"> time
 
event</span>=<span style="color: #000000">Event()
 
</span><span style="color: #0000ff">def</span><span style="color: #000000"> check():
    </span><span style="color: #0000ff">print</span>(<span style="color: #800000">‘</span><span style="color: #800000">checking MySQL...</span><span style="color: #800000">‘</span><span style="color: #000000">)
    time.sleep(</span>5<span style="color: #000000">)
    event.set()
 
</span><span style="color: #0000ff">def</span><span style="color: #000000"> conn():
    count</span>=1
    <span style="color: #0000ff">while</span> <span style="color: #0000ff">not</span><span style="color: #000000"> event.is_set():
        </span><span style="color: #0000ff">if</span> count > 3<span style="color: #000000">:
            </span><span style="color: #0000ff">raise</span> TimeoutError(<span style="color: #800000">‘</span><span style="color: #800000">超时</span><span style="color: #800000">‘</span><span style="color: #000000">)
        </span><span style="color: #0000ff">print</span>(<span style="color: #800000">‘</span><span style="color: #800000">%s try to connect MySQL time %s</span><span style="color: #800000">‘</span> %<span style="color: #000000">(current_thread().getName(),count))
        event.wait(</span>1<span style="color: #000000">)
        count</span>+=1
 
    <span style="color: #0000ff">print</span>(<span style="color: #800000">‘</span><span style="color: #800000">%s connected MySQL</span><span style="color: #800000">‘</span> %<span style="color: #000000">current_thread().getName())
 
</span><span style="color: #0000ff">if</span> <span style="color: #800080">__name__</span> == <span style="color: #800000">‘</span><span style="color: #800000">__main__</span><span style="color: #800000">‘</span><span style="color: #000000">:
    t1</span>=Thread(target=<span style="color: #000000">check)
    t2</span>=Thread(target=<span style="color: #000000">conn)
    t3</span>=Thread(target=<span style="color: #000000">conn)
    t4</span>=Thread(target=<span style="color: #000000">conn)
 
 
    t1.start()
    t2.start()
    t3.start()
    t4.start()</span>

1.5 定时器

定时器，指定n秒后执行某操作

<span style="color: #0000ff">from</span> threading <span style="color: #0000ff">import</span><span style="color: #000000"> Timer
 
 
</span><span style="color: #0000ff">def</span><span style="color: #000000"> hello(name):
    </span><span style="color: #0000ff">print</span>(<span style="color: #800000">"</span><span style="color: #800000">hello, world %s </span><span style="color: #800000">"</span> %<span style="color: #000000">name)
 
 
t </span>= Timer(3, hello,args=(<span style="color: #800000">‘</span><span style="color: #800000">egon</span><span style="color: #800000">‘</span><span style="color: #000000">,))
t.start()  </span><span style="color: #008000">#</span><span style="color: #008000"> after 1 seconds, "hello, world" will be printed</span>

1.6 线程queue

queue队列：使用import queue，用法与进程Queue一样

<span style="color: #0000ff">import</span><span style="color: #000000"> queue
 
q</span>=queue.Queue(3) <span style="color: #008000">#</span><span style="color: #008000">队列：先进先出</span>
<span style="color: #000000">
 
q.put(</span>1<span style="color: #000000">)
q.put(</span>2<span style="color: #000000">)
q.put(</span>3<span style="color: #000000">)
</span><span style="color: #008000">#</span><span style="color: #008000"> q.put(4)</span>
<span style="color: #008000">#</span><span style="color: #008000"> q.put_nowait(4)</span>
<span style="color: #008000">#</span><span style="color: #008000"> q.put(4,block=False)</span>
<span style="color: #000000">
q.put(</span>4,block=True,timeout=3<span style="color: #000000">)
 
 
</span><span style="color: #008000">#</span><span style="color: #008000"> print(q.get())</span>
<span style="color: #008000">#</span><span style="color: #008000"> print(q.get())</span>
<span style="color: #008000">#</span><span style="color: #008000"> print(q.get())</span>
<span style="color: #000000">
 
q</span>=queue.LifoQueue(3) <span style="color: #008000">#</span><span style="color: #008000">堆栈：后进先出</span>
<span style="color: #000000">
q.put(</span>1<span style="color: #000000">)
q.put(</span>2<span style="color: #000000">)
q.put(</span>3<span style="color: #000000">)
 
</span><span style="color: #0000ff">print</span><span style="color: #000000">(q.get())
</span><span style="color: #0000ff">print</span><span style="color: #000000">(q.get())
</span><span style="color: #0000ff">print</span><span style="color: #000000">(q.get())
 
q</span>=queue.PriorityQueue(3) <span style="color: #008000">#</span><span style="color: #008000">优先级队列</span>
<span style="color: #000000">
q.put((</span>10,<span style="color: #800000">‘</span><span style="color: #800000">a</span><span style="color: #800000">‘</span><span style="color: #000000">))
q.put((</span>-3,<span style="color: #800000">‘</span><span style="color: #800000">b</span><span style="color: #800000">‘</span><span style="color: #000000">))
q.put((</span>100,<span style="color: #800000">‘</span><span style="color: #800000">c</span><span style="color: #800000">‘</span><span style="color: #000000">))
 
</span><span style="color: #0000ff">print</span><span style="color: #000000">(q.get())
</span><span style="color: #0000ff">print</span><span style="color: #000000">(q.get())
</span><span style="color: #0000ff">print</span>(q.get())

1.7 进程池线程池

#提交任务的两种方式：

#同步调用：提交完任务后，就在原地等待，等待任务执行完毕，拿到任务的返回值，才能继续下一行代码，导致程序串行执行

#异步调用+回调机制：提交完任务后，不在原地等待，任务一旦执行完毕就会触发回调函数的执行，程序是并发执行

#进程的执行状态：

#阻塞

#非阻塞

1.7.1 同步调用示例：

# from multiprocessing import Pool

<span style="color: #0000ff">from</span> concurrent.futures <span style="color: #0000ff">import</span><span style="color: #000000"> ThreadPoolExecutor,ProcessPoolExecutor
</span><span style="color: #0000ff">import</span><span style="color: #000000"> time,random,os
 
</span><span style="color: #0000ff">def</span><span style="color: #000000"> task(n):
    </span><span style="color: #0000ff">print</span>(<span style="color: #800000">‘</span><span style="color: #800000">%s is ruuning</span><span style="color: #800000">‘</span> %<span style="color: #000000">os.getpid())
    time.sleep(random.randint(</span>1,3<span style="color: #000000">))
    </span><span style="color: #0000ff">return</span> n**2
 
<span style="color: #0000ff">def</span><span style="color: #000000"> handle(res):
    </span><span style="color: #0000ff">print</span>(<span style="color: #800000">‘</span><span style="color: #800000">handle res %s</span><span style="color: #800000">‘</span> %<span style="color: #000000">res)
 
</span><span style="color: #0000ff">if</span> <span style="color: #800080">__name__</span> == <span style="color: #800000">‘</span><span style="color: #800000">__main__</span><span style="color: #800000">‘</span><span style="color: #000000">:
    </span><span style="color: #008000">#</span><span style="color: #008000">同步调用</span>
<span style="color: #000000">
    pool</span>=ProcessPoolExecutor(2<span style="color: #000000">)
 
    </span><span style="color: #0000ff">for</span> i <span style="color: #0000ff">in</span> range(5<span style="color: #000000">):
        res</span>=<span style="color: #000000">pool.submit(task,i).result()
        </span><span style="color: #008000">#</span><span style="color: #008000"> print(res)</span>
<span style="color: #000000">
        handle(res)
 
    pool.shutdown(wait</span>=<span style="color: #000000">True)
    </span><span style="color: #008000">#</span><span style="color: #008000"> pool.submit(task,33333)</span>
    <span style="color: #0000ff">print</span>(<span style="color: #800000">‘</span><span style="color: #800000">主</span><span style="color: #800000">‘</span><span style="color: #000000">)
 </span>

1.7.2 异步调用示例：

<span style="color: #0000ff">from</span> concurrent.futures <span style="color: #0000ff">import</span><span style="color: #000000"> ThreadPoolExecutor,ProcessPoolExecutor
</span><span style="color: #0000ff">import</span><span style="color: #000000"> time,random,os
 
</span><span style="color: #0000ff">def</span><span style="color: #000000"> task(n):
    </span><span style="color: #0000ff">print</span>(<span style="color: #800000">‘</span><span style="color: #800000">%s is ruuning</span><span style="color: #800000">‘</span> %<span style="color: #000000">os.getpid())
    time.sleep(random.randint(</span>1,3<span style="color: #000000">))
    </span><span style="color: #008000">#</span><span style="color: #008000"> res=n**2</span>
    <span style="color: #008000">#</span><span style="color: #008000"> handle(res)</span>
    <span style="color: #0000ff">return</span> n**2
 
<span style="color: #0000ff">def</span><span style="color: #000000"> handle(res):
    res</span>=<span style="color: #000000">res.result()
    </span><span style="color: #0000ff">print</span>(<span style="color: #800000">‘</span><span style="color: #800000">handle res %s</span><span style="color: #800000">‘</span> %<span style="color: #000000">res)
 
</span><span style="color: #0000ff">if</span> <span style="color: #800080">__name__</span> == <span style="color: #800000">‘</span><span style="color: #800000">__main__</span><span style="color: #800000">‘</span><span style="color: #000000">:
    </span><span style="color: #008000">#</span><span style="color: #008000">异步调用</span>
<span style="color: #000000">
    pool</span>=ProcessPoolExecutor(2<span style="color: #000000">)
 
    </span><span style="color: #0000ff">for</span> i <span style="color: #0000ff">in</span> range(5<span style="color: #000000">):
        obj</span>=<span style="color: #000000">pool.submit(task,i)
        obj.add_done_callback(handle) </span><span style="color: #008000">#</span><span style="color: #008000">handle(obj)</span>
<span style="color: #000000">
 
    pool.shutdown(wait</span>=<span style="color: #000000">True)
    </span><span style="color: #0000ff">print</span>(<span style="color: #800000">‘</span><span style="color: #800000">主</span><span style="color: #800000">‘</span>)

1.7.3 线程池

<span style="color: #0000ff">from</span> concurrent.futures <span style="color: #0000ff">import</span><span style="color: #000000"> ThreadPoolExecutor
</span><span style="color: #0000ff">from</span> threading <span style="color: #0000ff">import</span><span style="color: #000000"> current_thread
</span><span style="color: #0000ff">import</span><span style="color: #000000"> requests
</span><span style="color: #0000ff">import</span><span style="color: #000000"> time
 
</span><span style="color: #0000ff">def</span><span style="color: #000000"> get(url):
    </span><span style="color: #0000ff">print</span>(<span style="color: #800000">‘</span><span style="color: #800000">%s GET %s</span><span style="color: #800000">‘</span> %<span style="color: #000000">(current_thread().getName(),url))
    response</span>=<span style="color: #000000">requests.get(url)
    time.sleep(</span>2<span style="color: #000000">)
    </span><span style="color: #0000ff">if</span> response.status_code == 200<span style="color: #000000">:
        </span><span style="color: #0000ff">return</span> {<span style="color: #800000">‘</span><span style="color: #800000">url</span><span style="color: #800000">‘</span>:url,<span style="color: #800000">‘</span><span style="color: #800000">content</span><span style="color: #800000">‘</span><span style="color: #000000">:response.text}
 
</span><span style="color: #0000ff">def</span><span style="color: #000000"> parse(res):
    res</span>=<span style="color: #000000">res.result()
    </span><span style="color: #0000ff">print</span>(<span style="color: #800000">‘</span><span style="color: #800000">parse:[%s] res:[%s]</span><span style="color: #800000">‘</span> %(res[<span style="color: #800000">‘</span><span style="color: #800000">url</span><span style="color: #800000">‘</span>],len(res[<span style="color: #800000">‘</span><span style="color: #800000">content</span><span style="color: #800000">‘</span><span style="color: #000000">])))
 
 
</span><span style="color: #0000ff">if</span> <span style="color: #800080">__name__</span> == <span style="color: #800000">‘</span><span style="color: #800000">__main__</span><span style="color: #800000">‘</span><span style="color: #000000">:
    pool</span>=ThreadPoolExecutor(2<span style="color: #000000">)
 
    urls</span>=<span style="color: #000000">[
        </span><span style="color: #800000">‘</span><span style="color: #800000">https://www.baidu.com</span><span style="color: #800000">‘</span><span style="color: #000000">,
        </span><span style="color: #800000">‘</span><span style="color: #800000">https://www.python.org</span><span style="color: #800000">‘</span><span style="color: #000000">,
        </span><span style="color: #800000">‘</span><span style="color: #800000">https://www.openstack.org</span><span style="color: #800000">‘</span><span style="color: #000000">,
        </span><span style="color: #800000">‘</span><span style="color: #800000">https://www.openstack.org</span><span style="color: #800000">‘</span><span style="color: #000000">,
        </span><span style="color: #800000">‘</span><span style="color: #800000">https://www.openstack.org</span><span style="color: #800000">‘</span><span style="color: #000000">,
        </span><span style="color: #800000">‘</span><span style="color: #800000">https://www.openstack.org</span><span style="color: #800000">‘</span><span style="color: #000000">,
        </span><span style="color: #800000">‘</span><span style="color: #800000">https://www.openstack.org</span><span style="color: #800000">‘</span><span style="color: #000000">,
        </span><span style="color: #800000">‘</span><span style="color: #800000">https://www.openstack.org</span><span style="color: #800000">‘</span><span style="color: #000000">,
        </span><span style="color: #800000">‘</span><span style="color: #800000">https://www.openstack.org</span><span style="color: #800000">‘</span><span style="color: #000000">,
        </span><span style="color: #800000">‘</span><span style="color: #800000">https://www.openstack.org</span><span style="color: #800000">‘</span><span style="color: #000000">,
        </span><span style="color: #800000">‘</span><span style="color: #800000">https://www.openstack.org</span><span style="color: #800000">‘</span><span style="color: #000000">,
        </span><span style="color: #800000">‘</span><span style="color: #800000">https://www.openstack.org</span><span style="color: #800000">‘</span><span style="color: #000000">,
    ]
    </span><span style="color: #0000ff">for</span> url <span style="color: #0000ff">in</span><span style="color: #000000"> urls:
        pool.submit(get,url).add_done_callback(parse)
 
    pool.shutdown(wait</span>=True)

1.8 协程

单纯地切换反而会降低运行效率

协程：是单线程下的并发，又称微线程，纤程。英文名Coroutine。一句话说明什么是线程：协程是一种用户态的轻量级线程，即协程是由用户程序自己控制调度的。

总结协程特点：

必须在只有一个单线程里实现并发

修改共享数据不需加锁

用户程序里自己保存多个控制流的上下文栈

附加：一个协程遇到IO操作自动切换到其它协程（如何实现检测IO，yield、greenlet都无法实现，就用到了gevent模块（select机制））

1.8.1 串行执行

<span style="color: #0000ff">import</span><span style="color: #000000"> time
</span><span style="color: #0000ff">def</span><span style="color: #000000"> consumer(res):
    </span><span style="color: #800000">‘‘‘</span><span style="color: #800000">任务1:接收数据,处理数据</span><span style="color: #800000">‘‘‘</span>
    <span style="color: #0000ff">pass</span>
 
<span style="color: #0000ff">def</span><span style="color: #000000"> producer():
    </span><span style="color: #800000">‘‘‘</span><span style="color: #800000">任务2:生产数据</span><span style="color: #800000">‘‘‘</span><span style="color: #000000">
    res</span>=<span style="color: #000000">[]
    </span><span style="color: #0000ff">for</span> i <span style="color: #0000ff">in</span> range(10000000<span style="color: #000000">):
        res.append(i)
    </span><span style="color: #0000ff">return</span><span style="color: #000000"> res
 
start</span>=<span style="color: #000000">time.time()
</span><span style="color: #008000">#</span><span style="color: #008000">串行执行</span>
<span style="color: #000000">
res</span>=<span style="color: #000000">producer()
consumer(res)
stop</span>=<span style="color: #000000">time.time()
</span><span style="color: #0000ff">print</span>(stop-<span style="color: #000000">start)
 </span>

1.8.2 基于yield并发执行

<span style="color: #0000ff">import</span><span style="color: #000000"> time
</span><span style="color: #0000ff">def</span><span style="color: #000000"> consumer():
    </span><span style="color: #800000">‘‘‘</span><span style="color: #800000">任务1:接收数据,处理数据</span><span style="color: #800000">‘‘‘</span>
    <span style="color: #0000ff">while</span><span style="color: #000000"> True:
        </span><span style="color: #0000ff">print</span>(<span style="color: #800000">‘</span><span style="color: #800000">consumer</span><span style="color: #800000">‘</span><span style="color: #000000">)
        x</span>=<span style="color: #0000ff">yield</span><span style="color: #000000">
        time.sleep(</span>100<span style="color: #000000">)
 
</span><span style="color: #0000ff">def</span><span style="color: #000000"> producer():
    </span><span style="color: #800000">‘‘‘</span><span style="color: #800000">任务2:生产数据</span><span style="color: #800000">‘‘‘</span><span style="color: #000000">
    g</span>=<span style="color: #000000">consumer()
    next(g)
    </span><span style="color: #0000ff">for</span> i <span style="color: #0000ff">in</span> range(10000000<span style="color: #000000">):
        </span><span style="color: #0000ff">print</span>(<span style="color: #800000">‘</span><span style="color: #800000">producer</span><span style="color: #800000">‘</span><span style="color: #000000">)
        g.send(i)
 
start</span>=<span style="color: #000000">time.time()
</span><span style="color: #008000">#</span><span style="color: #008000">基于yield保存状态,实现两个任务直接来回切换,即并发的效果</span>
<span style="color: #008000">#</span><span style="color: #008000">PS:如果每个任务中都加上打印,那么明显地看到两个任务的打印是你一次我一次,即并发执行的.</span>
<span style="color: #000000">
producer()
 
stop</span>=<span style="color: #000000">time.time()
</span><span style="color: #0000ff">print</span>(stop-start) <span style="color: #008000">#
</span>

1.9 greenlet模块

如果我们在单个线程内有20个任务，要想实现在多个任务之间切换，使用yield生成器的方式过于麻烦（需要先得到初始化一次的生成器，然后再调用send。。。非常麻烦），而使用greenlet模块可以非常简单地实现这20个任务直接的切换

安装模块

pip3 install greenlet

<span style="color: #0000ff">from</span> greenlet <span style="color: #0000ff">import</span><span style="color: #000000"> greenlet
</span><span style="color: #0000ff">import</span><span style="color: #000000"> time
 
</span><span style="color: #0000ff">def</span><span style="color: #000000"> eat(name):
    </span><span style="color: #0000ff">print</span>(<span style="color: #800000">‘</span><span style="color: #800000">%s eat 1</span><span style="color: #800000">‘</span> %<span style="color: #000000">name)
    time.sleep(</span>1000<span style="color: #000000">)
    g2.switch(</span><span style="color: #800000">‘</span><span style="color: #800000">egon</span><span style="color: #800000">‘</span><span style="color: #000000">)
    </span><span style="color: #0000ff">print</span>(<span style="color: #800000">‘</span><span style="color: #800000">%s eat 2</span><span style="color: #800000">‘</span> %<span style="color: #000000">name)
    g2.switch()
 
 
</span><span style="color: #0000ff">def</span><span style="color: #000000"> play(name):
    </span><span style="color: #0000ff">print</span>(<span style="color: #800000">‘</span><span style="color: #800000">%s play 1</span><span style="color: #800000">‘</span> %<span style="color: #000000"> name)
    g1.switch()  </span><span style="color: #008000">#</span><span style="color: #008000">可以在第一次switch时传入参数，以后都不需要</span>
    <span style="color: #0000ff">print</span>(<span style="color: #800000">‘</span><span style="color: #800000">%s play 2</span><span style="color: #800000">‘</span> %<span style="color: #000000"> name)
 
g1</span>=<span style="color: #000000">greenlet(eat)
g2</span>=greenlet(play)

greenlet只是提供了一种比generator更加便捷的切换方式，当切到一个任务执行时如果遇到io，那就原地阻塞，仍然是没有解决遇到IO自动切换来提升效率的问题。

单线程里的这20个任务的代码通常会既有计算操作又有阻塞操作，我们完全可以在执行任务1时遇到阻塞，就利用阻塞的时间去执行任务2。。。。如此，才能提高效率，这就用到了Gevent模块。

1.10 gevent模块

Gevent 是一个第三方库，可以轻松通过gevent实现并发同步或异步编程，在gevent中用到的主要模式是Greenlet, 它是以C扩展模块形式接入Python的轻量级协程。 Greenlet全部运行在主程序操作系统进程的内部，但它们被协作式地调度。

#用法

g1=gevent.spawn(func,1,,2,3,x=4,y=5<span style="color: #000000">)创建一个协程对象g1，spawn括号内第一个参数是函数名，如eat，后面可以有多个参数，可以是位置实参或关键字实参，都是传给函数eat的
 
g2</span>=<span style="color: #000000">gevent.spawn(func2)
 
g1.join() </span><span style="color: #008000">#</span><span style="color: #008000">等待g1结束</span>
<span style="color: #000000">
 
g2.join() </span><span style="color: #008000">#</span><span style="color: #008000">等待g2结束</span>
 
<span style="color: #008000">#</span><span style="color: #008000">或者上述两步合作一步：gevent.joinall([g1,g2])</span>
<span style="color: #000000">
 
g1.value</span><span style="color: #008000">#</span><span style="color: #008000">拿到func1的返回值</span>

<span style="color: #0000ff">from</span> gevent <span style="color: #0000ff">import</span><span style="color: #000000"> monkey;monkey.patch_all()
</span><span style="color: #0000ff">import</span><span style="color: #000000"> gevent
</span><span style="color: #0000ff">import</span><span style="color: #000000"> time
 
</span><span style="color: #0000ff">def</span><span style="color: #000000"> eat(name):
    </span><span style="color: #0000ff">print</span>(<span style="color: #800000">‘</span><span style="color: #800000">%s eat 1</span><span style="color: #800000">‘</span> %<span style="color: #000000">name)
    </span><span style="color: #008000">#</span><span style="color: #008000"> gevent.sleep(3)</span>
<span style="color: #000000">
    time.sleep(</span>3<span style="color: #000000">)
    </span><span style="color: #0000ff">print</span>(<span style="color: #800000">‘</span><span style="color: #800000">%s eat 2</span><span style="color: #800000">‘</span> %<span style="color: #000000">name)
 
 
</span><span style="color: #0000ff">def</span><span style="color: #000000"> play(name):
    </span><span style="color: #0000ff">print</span>(<span style="color: #800000">‘</span><span style="color: #800000">%s play 1</span><span style="color: #800000">‘</span> %<span style="color: #000000"> name)
    </span><span style="color: #008000">#</span><span style="color: #008000"> gevent.sleep(2)</span>
<span style="color: #000000">
    time.sleep(</span>3<span style="color: #000000">)
    </span><span style="color: #0000ff">print</span>(<span style="color: #800000">‘</span><span style="color: #800000">%s play 2</span><span style="color: #800000">‘</span> %<span style="color: #000000"> name)
 
g1</span>=gevent.spawn(eat,<span style="color: #800000">‘</span><span style="color: #800000">egon</span><span style="color: #800000">‘</span><span style="color: #000000">)
g2</span>=gevent.spawn(play,<span style="color: #800000">‘</span><span style="color: #800000">alex</span><span style="color: #800000">‘</span><span style="color: #000000">)
</span><span style="color: #008000">#</span><span style="color: #008000"> gevent.sleep(1)</span>
 
<span style="color: #008000">#</span><span style="color: #008000"> g1.join()</span>
<span style="color: #008000">#</span><span style="color: #008000"> g2.join()</span>
<span style="color: #000000">
gevent.joinall([g1,g2])</span>

练习

通过gevent实现单线程下的socket并发（from gevent import monkey;monkey.patch_all()一定要放到导入socket模块之前，否则gevent无法识别socket的阻塞）

服务端

<span style="color: #0000ff">from</span> gevent <span style="color: #0000ff">import</span><span style="color: #000000"> monkey,spawn;monkey.patch_all()
</span><span style="color: #0000ff">from</span> threading <span style="color: #0000ff">import</span><span style="color: #000000"> current_thread
</span><span style="color: #0000ff">from</span> socket <span style="color: #0000ff">import</span> *
 
<span style="color: #0000ff">def</span><span style="color: #000000"> comunicate(conn):
    </span><span style="color: #0000ff">print</span>(<span style="color: #800000">‘</span><span style="color: #800000">子线程：%s</span><span style="color: #800000">‘</span> %<span style="color: #000000">current_thread().getName())
    </span><span style="color: #0000ff">while</span><span style="color: #000000"> True:
        </span><span style="color: #0000ff">try</span><span style="color: #000000">:
            data</span>=conn.recv(1024<span style="color: #000000">)
            </span><span style="color: #0000ff">if</span> <span style="color: #0000ff">not</span> data:<span style="color: #0000ff">break</span><span style="color: #000000">
            conn.send(data.upper())
        </span><span style="color: #0000ff">except</span><span style="color: #000000"> ConnectionResetError:
            </span><span style="color: #0000ff">break</span><span style="color: #000000">
    conn.close()
 
</span><span style="color: #0000ff">def</span><span style="color: #000000"> server(ip,port):
    </span><span style="color: #0000ff">print</span>(<span style="color: #800000">‘</span><span style="color: #800000">主线程：%s</span><span style="color: #800000">‘</span> %<span style="color: #000000">current_thread().getName())
    server </span>=<span style="color: #000000"> socket(AF_INET, SOCK_STREAM)
    server.bind((ip,port))
    server.listen(</span>5<span style="color: #000000">)
 
    </span><span style="color: #0000ff">while</span><span style="color: #000000"> True:
        conn, addr </span>=<span style="color: #000000"> server.accept()
        </span><span style="color: #0000ff">print</span><span style="color: #000000">(addr)
        </span><span style="color: #008000">#</span><span style="color: #008000"> comunicate(conn)</span>
        <span style="color: #008000">#</span><span style="color: #008000"> t=Thread(target=comunicate,args=(conn,))</span>
        <span style="color: #008000">#</span><span style="color: #008000"> t.start()</span>
<span style="color: #000000">
        spawn(comunicate,conn)
 
    server.close()
 
</span><span style="color: #0000ff">if</span> <span style="color: #800080">__name__</span> == <span style="color: #800000">‘</span><span style="color: #800000">__main__</span><span style="color: #800000">‘</span><span style="color: #000000">:
    g</span>=spawn(server,<span style="color: #800000">‘</span><span style="color: #800000">127.0.0.1</span><span style="color: #800000">‘</span>, 8081<span style="color: #000000">)
    g.join()</span>

客户端

多线程并发多个客户端

<span style="color: #0000ff">from</span> socket <span style="color: #0000ff">import</span> *
<span style="color: #0000ff">from</span> threading <span style="color: #0000ff">import</span><span style="color: #000000"> current_thread,Thread
 
</span><span style="color: #0000ff">def</span><span style="color: #000000"> client():
    client</span>=<span style="color: #000000">socket(AF_INET,SOCK_STREAM)
    client.connect((</span><span style="color: #800000">‘</span><span style="color: #800000">127.0.0.1</span><span style="color: #800000">‘</span>,8081<span style="color: #000000">))
 
    </span><span style="color: #0000ff">while</span><span style="color: #000000"> True:
        client.send((</span><span style="color: #800000">‘</span><span style="color: #800000">%s say hello</span><span style="color: #800000">‘</span> %current_thread().getName()).encode(<span style="color: #800000">‘</span><span style="color: #800000">utf-8</span><span style="color: #800000">‘</span><span style="color: #000000">))
        data</span>=client.recv(1024<span style="color: #000000">)
        </span><span style="color: #0000ff">print</span>(data.decode(<span style="color: #800000">‘</span><span style="color: #800000">utf-8</span><span style="color: #800000">‘</span><span style="color: #000000">))
 
    client.close()
 
</span><span style="color: #0000ff">if</span> <span style="color: #800080">__name__</span> == <span style="color: #800000">‘</span><span style="color: #800000">__main__</span><span style="color: #800000">‘</span><span style="color: #000000">:
    </span><span style="color: #0000ff">for</span> i <span style="color: #0000ff">in</span> range(500<span style="color: #000000">):
        t</span>=Thread(target=<span style="color: #000000">client)
        t.start()</span>

1.11 MySQL数据库相关概念

MySQL是一个关系型数据库管理系统，由瑞典MySQL AB 公司开发，目前属于 Oracle 旗下公司。MySQL 最流行的关系型数据库管理系统，在 WEB 应用方面MySQL是最好的 RDBMS (Relational Database Management System，关系数据库管理系统) 应用软件之一。

1、数据库服务器：计算机

2、数据库管理软件：MySQL

3、数据库/库：文件夹

4、表:文件

5、记录:一个事物的一系列典型的特征：egon,male,18,oldgirl

6、数据：事物的特征，sex=‘male‘

1.11.1 mysql是什么

#mysql就是一个基于socket编写的C/S架构的软件

#客户端软件

　　mysql自带：如mysql命令，mysqldump命令等

　　python模块：如pymysql

1.11.2 数据库管理软件分类

#分两大类：

　　关系型：如sqllite，db2，oracle，access，sql server，MySQL，注意：sql语句通用

　　非关系型：mongodb，redis，memcache

#可以简单的理解为：

关系型数据库需要有表结构

非关系型数据库是key-value存储的，没有表结构

1.11.3 下载安装

1.11.3.1 Linux版本

一、二进制rpm包安装

yum -y install mysql-server mysql

二、源码安装

1.解压tar包

cd /<span style="color: #000000">software
tar </span>-xzvf mysql-5.6.21-linux-glibc2.5-<span style="color: #000000">x86_64.tar.gz
mv mysql</span>-5.6.21-linux-glibc2.5-x86_64 mysql-5.6.21

2.添加用户与组

<span style="color: #000000">groupadd mysql
useradd </span>-r -<span style="color: #000000">g mysql mysql
chown </span>-R mysql:mysql mysql-5.6.21

3.安装数据库

<span style="color: #000000">su mysql
cd mysql</span>-5.6.21/<span style="color: #000000">scripts
.</span>/mysql_install_db --user=mysql --basedir=/software/mysql-5.6.21 --datadir=/software/mysql-5.6.21/data

4.配置文件

cd /software/mysql-5.6.21/support-<span style="color: #000000">files
cp my</span>-default.cnf /etc/<span style="color: #000000">my.cnf
cp mysql.server </span>/etc/init.d/<span style="color: #000000">mysql
vim </span>/etc/init.d/mysql   <span style="color: #008000">#</span><span style="color: #008000">若mysql的安装目录是/usr/local/mysql,则可省略此步</span>
<span style="color: #000000">
修改文件中的两个变更值
basedir</span>=/software/mysql-5.6.21<span style="color: #000000">
datadir</span>=/software/mysql-5.6.21/<span style="color: #000000">data
 </span>

5.配置环境变量

vim /etc/<span style="color: #000000">profile
export MYSQL_HOME</span>=<span style="color: #800000">"</span><span style="color: #800000">/software/mysql-5.6.21</span><span style="color: #800000">"</span><span style="color: #000000">
export PATH</span>=<span style="color: #800000">"</span><span style="color: #800000">$PATH:$MYSQL_HOME/bin</span><span style="color: #800000">"</span><span style="color: #000000">
source </span>/etc/profile

6.添加自启动服务

chkconfig --<span style="color: #000000">add mysql
chkconfig mysql on</span>

7.启动mysql

service mysql start

8.登录mysql及改密码与配置远程访问

mysqladmin -u root password <span style="color: #800000">‘</span><span style="color: #800000">your_password</span><span style="color: #800000">‘</span>     <span style="color: #008000">#</span><span style="color: #008000">修改root用户密码</span>
<span style="color: #000000">
mysql </span>-u root -p     <span style="color: #008000">#</span><span style="color: #008000">登录mysql,需要输入密码</span>
<span style="color: #000000">
mysql</span>>GRANT ALL PRIVILEGES ON *.* TO <span style="color: #800000">‘</span><span style="color: #800000">root</span><span style="color: #800000">‘</span>@<span style="color: #800000">‘</span><span style="color: #800000">%</span><span style="color: #800000">‘</span> IDENTIFIED BY <span style="color: #800000">‘</span><span style="color: #800000">your_password</span><span style="color: #800000">‘</span> WITH GRANT OPTION;     <span style="color: #008000">#</span><span style="color: #008000">允许root用户远程访问</span>
<span style="color: #000000">
mysql</span>>FLUSH PRIVILEGES;     <span style="color: #008000">#</span><span style="color: #008000">刷新权限</span>

三、源码安装mariadb

1. 解压

tar zxvf  mariadb-5.5.31-linux-<span style="color: #000000">x86_64.tar.gz  
mv mariadb</span>-5.5.31-linux-x86_64 /usr/local/mysql //必需这样，很多脚本或可执行程序都会直接访问这个目录

2. 权限

groupadd mysql             //<span style="color: #000000">增加 mysql 属组
useradd </span>-g mysql mysql     //<span style="color: #000000">增加 mysql 用户 并归于mysql 属组
chown mysql:mysql </span>-Rf  /usr/local/mysql    //<span style="color: #000000"> 设置 mysql 目录的用户及用户组归属。
chmod </span>+x -Rf /usr/local/mysql    //赐予可执行权限

3. 拷贝配置文件

cp /usr/local/mysql/support-files/my-medium.cnf /etc/my.cnf     //复制默认mysql配置 文件到/etc目录

4. 初始化

/usr/local/mysql/scripts/mysql_install_db --user=mysql          //<span style="color: #000000">初始化数据库
cp  </span>/usr/local/mysql/support-files/mysql.server    /etc/init.d/mysql    //<span style="color: #000000">复制mysql服务程序 到系统目录
chkconfig  mysql on     </span>//<span style="color: #000000">添加mysql 至系统服务并设置为开机启动
service  mysql  start  </span>//启动mysql

5. 环境变量配置

vim /etc/profile   //<span style="color: #000000">编辑profile,将mysql的可执行路径加入系统PATH
export PATH</span>=/usr/local/mysql/<span style="color: #000000">bin:$PATH
source </span>/etc/profile  //使PATH生效。

6. 账号密码

mysqladmin -u root password <span style="color: #800000">‘</span><span style="color: #800000">yourpassword</span><span style="color: #800000">‘</span> //<span style="color: #000000">设定root账号及密码
mysql </span>-u root -p  //<span style="color: #000000">使用root用户登录mysql
use mysql  </span>//<span style="color: #000000">切换至mysql数据库。
select user,host,password </span><span style="color: #0000ff">from</span> user; //<span style="color: #000000">查看系统权限
drop user </span><span style="color: #800000">‘‘</span>@<span style="color: #800000">‘</span><span style="color: #800000">localhost</span><span style="color: #800000">‘</span>; //<span style="color: #000000">删除不安全的账户
drop user root@</span><span style="color: #800000">‘</span><span style="color: #800000">::1</span><span style="color: #800000">‘</span><span style="color: #000000">;
drop user root@</span>127.0.0.1<span style="color: #000000">;
select user,host,password </span><span style="color: #0000ff">from</span> user; //<span style="color: #000000">再次查看系统权限，确保不安全的账户均被删除。
flush privileges;  </span>//刷新权限

7. 一些必要的初始配置

1）修改字符集为UTF8

vi /etc/<span style="color: #000000">my.cnf
在[client]下面添加 default</span>-character-set =<span style="color: #000000"> utf8
在[mysqld]下面添加 character_set_server </span>= utf8

2）增加错误日志

vi /etc/<span style="color: #000000">my.cnf
在[mysqld]下面添加：
log</span>-error = /usr/local/mysql/log/<span style="color: #000000">error.log
general</span>-log-file = /usr/local/mysql/log/<span style="color: #000000">mysql.log
</span>3<span style="color: #000000">) 设置为不区分大小写，linux下默认会区分大小写。
vi </span>/etc/<span style="color: #000000">my.cnf
在[mysqld]下面添加：
lower_case_table_name</span>=1

修改完重启：

service  mysql  restart

1.11.3.2 Window版本

安装

#1、下载：MySQL Community Server 5.7.16

http://dev.mysql.com/downloads/mysql/

#2、解压

如果想要让MySQL安装在指定目录，那么就将解压后的文件夹移动到指定目录，如：C:\mysql-5.7.16-winx64

#3、添加环境变量

【右键计算机】--》【属性】--》【高级系统设置】--》【高级】--》【环境变量】--》【在第二个内容框中找到变量名为Path 的一行，双击】 --> 【将MySQL的bin目录路径追加到变值值中，用；分割】

#4、初始化

mysqld --initialize-insecure

#5、启动MySQL服务

mysqld <span style="color: #008000">#</span><span style="color: #008000"> 启动MySQL服务</span>

#6、启动MySQL客户端并连接MySQL服务

mysql -u root -p <span style="color: #008000">#</span><span style="color: #008000"> 连接MySQL服务器</span>

将MySQL服务制作成windows服务

上一步解决了一些问题，但不够彻底，因为在执行【mysqd】启动MySQL服务器时，当前终端会被hang住，那么做一下设置即可解决此问题：

注意：--install前，必须用mysql启动命令的绝对路径

# 制作MySQL的Windows服务，在终端执行此命令：

<span style="color: #800000">"</span><span style="color: #800000">c:\mysql-5.7.16-winx64\bin\mysqld</span><span style="color: #800000">"</span> --install

# 移除MySQL的Windows服务，在终端执行此命令：

<span style="color: #800000">"</span><span style="color: #800000">c:\mysql-5.7.16-winx64\bin\mysqld</span><span style="color: #800000">"</span> --remove

注册成服务之后，以后再启动和关闭MySQL服务时，仅需执行如下命令：

# 启动MySQL服务

net start mysql

# 关闭MySQL服务

net stop mysql

1.12 重置密码

1.12.1 设置密码

C:\Users\Administrator> mysqladmin -uroot -p password <span style="color: #800000">"</span><span style="color: #800000">123</span><span style="color: #800000">"</span>

1.12.2 重置密码

<span style="color: #000000">net stop MySQL
mysqld </span>--skip-grant-<span style="color: #000000">tables
mysql </span>-uroot -<span style="color: #000000">p
    update mysql.user set password</span>=password(<span style="color: #800000">""</span>) where user=<span style="color: #800000">‘</span><span style="color: #800000">root</span><span style="color: #800000">‘</span> <span style="color: #0000ff">and</span> host=<span style="color: #800000">"</span><span style="color: #800000">localhost</span><span style="color: #800000">"</span><span style="color: #000000">;
    flush privileges;
 
C:\Users\Administrator</span>>tasklist |<span style="color: #000000">findstr mysql
mysqld.exe                    </span>6316 Console                    1    454,544<span style="color: #000000"> K
 
C:\Users\Administrator</span>>taskkill /F /PID 6316<span style="color: #000000">
成功: 已终止 PID 为 </span>6316<span style="color: #000000"> 的进程。
 
C:\Users\Administrator</span>><span style="color: #000000">net start MySQL
MySQL 服务正在启动 .
MySQL 服务已经启动成功。</span>

1.13 统一字符编码

#1. 修改配置文件

<span style="color: #000000">[mysqld]
default</span>-character-set=<span style="color: #000000">utf8
[client]
default</span>-character-set=<span style="color: #000000">utf8
[mysql]
default</span>-character-set=<span style="color: #000000">utf8
 
</span><span style="color: #008000">#</span><span style="color: #008000">mysql5.5以上：修改方式有所改动</span>
<span style="color: #000000">
[mysqld]
character</span>-set-server=<span style="color: #000000">utf8
collation</span>-server=<span style="color: #000000">utf8_general_ci
[client]
default</span>-character-set=<span style="color: #000000">utf8
[mysql]
default</span>-character-set=utf8

#2. 重启服务

#3. 查看修改结果：

mysql><span style="color: #000000"> \s
show variables like </span><span style="color: #800000">‘</span><span style="color: #800000">%char%</span><span style="color: #800000">‘</span>

1.14 初识SQL

有了mysql这个数据库软件，就可以将程序员从对数据的管理中解脱出来，专注于对程序逻辑的编写

mysql服务端软件即mysqld帮我们管理好文件夹以及文件，前提是作为使用者的我们，需要下载mysql的客户端，或者其他模块来连接到mysqld，然后使用mysql软件规定的语法格式去提交自己命令，实现对文件夹或文件的管理。该语法即sql（Structured Query Language 即结构化查询语言）

SQL语言主要用于存取数据、查询数据、更新数据和管理关系数据库系统,SQL语言由IBM开发。SQL语言分为3种类型：

#1、DDL语句数据库定义语言：数据库、表、视图、索引、存储过程，例如CREATE DROP ALTER

#2、DML语句数据库操纵语言：插入数据INSERT、删除数据DELETE、更新数据UPDATE、查询数据SELECT

#3、DCL语句数据库控制语言：例如控制用户的访问权限GRANT、REVOKE

1.14.1 操作文件夹（库）

1.14.1.1 增

create database db1 charset utf8;

1.14.1.2 查

<span style="color: #000000">show databases;
show create database db1;</span>

1.14.1.3 改

alter database db1 charset gbk;

1.14.1.4 删

drop database db1;

1.14.2 操作文件（表）

1.14.2.1 查看当前所在的文件夹:

select database();

1.14.2.2 切换文件夹：

use db1;

1.14.2.3 增

create table t1(id int,name char);

1.14.2.4 查

<span style="color: #000000">show tables;
show create table t1;
desc t1;</span>

1.14.2.5 改

<span style="color: #000000">alter table t1 add sex char;
alter table t1 drop sex;
alter table t1 modify name char(</span>16<span style="color: #000000">);
alter table t1 change name Name char(</span>13);

1.14.2.6 删

drop table t1;

1.14.3 操作文件的内容（记录）

1.14.3.1 增

<span style="color: #000000">insert into db1.t1 values
 (</span>1,<span style="color: #800000">‘</span><span style="color: #800000">egon</span><span style="color: #800000">‘</span><span style="color: #000000">),
 (</span>2,<span style="color: #800000">‘</span><span style="color: #800000">alex</span><span style="color: #800000">‘</span><span style="color: #000000">),
 (</span>3,<span style="color: #800000">‘</span><span style="color: #800000">wxx</span><span style="color: #800000">‘</span>);

1.14.3.2 查

select id,name <span style="color: #0000ff">from</span><span style="color: #000000"> db1.t1;
select </span>* <span style="color: #0000ff">from</span> db1.t1;

1.14.3.3 改

update t1 set name=<span style="color: #800000">‘</span><span style="color: #800000">SB</span><span style="color: #800000">‘</span> where id=2;

1.14.3.4 删

delete <span style="color: #0000ff">from</span> t1 where id=2;

1.15 存储引擎

储引擎即表类型，mysql根据不同的表类型会有不同的处理机制

查看引擎

show engines;

创建引擎

create table t1(id int)engine=<span style="color: #000000">innodb;
create table t2(id int)engine</span>=<span style="color: #000000">myisam;
create table t3(id int)engine</span>=<span style="color: #000000">memory;
create table t4(id int)engine</span>=blackhole;

1.16 数值类型

1.16.1 整型(默认有符号)

<span style="color: #000000">create table t8(n tinyint);
insert into t8 values(</span>-1<span style="color: #000000">);
insert into t8 values(</span>128<span style="color: #000000">);
insert into t8 values(</span>-129<span style="color: #000000">);
 
create table t9(n tinyint unsigned);
insert into t9 values(</span>-1),(256);

#整型的宽度代表显示宽度

create table t11(n int(3<span style="color: #000000">) unsigned zerofill);
create table t12(n int unsigned zerofill);
 
create table t13(
    id int
);
 </span>

1.16.2 浮点型

create table t13(x float(255,30<span style="color: #000000">));
create table t14(x double(</span>255,30<span style="color: #000000">));
create table t15(x decimal(</span>65,30<span style="color: #000000">));
 
 
insert into t13 values(</span>1.111111111111111111111111111111<span style="color: #000000">);
insert into t14 values(</span>1.111111111111111111111111111111<span style="color: #000000">);
insert into t15 values(</span>1.111111111111111111111111111111);

1.17 日期类型

<span style="color: #000000">create table student(
    id int,
    name char(</span>16<span style="color: #000000">),
    born_year year,
    birth_date date,
    class_time time,
    reg_time datetime
);
 
insert into student values
(</span>1,<span style="color: #800000">‘</span><span style="color: #800000">egon</span><span style="color: #800000">‘</span><span style="color: #000000">,now(),now(),now(),now())
;
 
insert into student values
(</span>2,<span style="color: #800000">‘</span><span style="color: #800000">alex</span><span style="color: #800000">‘</span>,<span style="color: #800000">‘</span><span style="color: #800000">1999</span><span style="color: #800000">‘</span>,<span style="color: #800000">‘</span><span style="color: #800000">1999-11-11</span><span style="color: #800000">‘</span>,<span style="color: #800000">‘</span><span style="color: #800000">11:11:11</span><span style="color: #800000">‘</span>,<span style="color: #800000">"</span><span style="color: #800000">1999-11-11 11:11:11</span><span style="color: #800000">"</span>)

1.18 字符类型

char:定长

varchar：变长

#宽度代表的是字符的个数

create table t16(name char(5<span style="color: #000000">));
create table t17(name varchar(</span>5<span style="color: #000000">));
 
insert into t16 values(</span><span style="color: #800000">‘</span><span style="color: #800000">李杰 </span><span style="color: #800000">‘</span>); <span style="color: #008000">#</span><span style="color: #008000">‘李杰   ‘</span>
<span style="color: #000000">
insert into t17 values(</span><span style="color: #800000">‘</span><span style="color: #800000">李杰 </span><span style="color: #800000">‘</span>); <span style="color: #008000">#</span><span style="color: #008000">‘李杰 ‘</span>
<span style="color: #000000">
 
select char_length(name) </span><span style="color: #0000ff">from</span> t16; <span style="color: #008000">#</span><span style="color: #008000">5</span>
<span style="color: #000000">
select char_length(name) </span><span style="color: #0000ff">from</span> t17; <span style="color: #008000">#</span><span style="color: #008000">3</span>
<span style="color: #000000">
 
mysql</span>> set sql_mode=<span style="color: #800000">‘</span><span style="color: #800000">PAD_CHAR_TO_FULL_LENGTH</span><span style="color: #800000">‘</span><span style="color: #000000">;
 
select </span>* <span style="color: #0000ff">from</span> t16 where name=<span style="color: #800000">‘</span><span style="color: #800000">李杰</span><span style="color: #800000">‘</span><span style="color: #000000">;
select </span>* <span style="color: #0000ff">from</span> t17 where name=<span style="color: #800000">‘</span><span style="color: #800000">李杰</span><span style="color: #800000">‘</span><span style="color: #000000">;
 
select </span>* <span style="color: #0000ff">from</span> t16 where name like <span style="color: #800000">‘</span><span style="color: #800000">李杰</span><span style="color: #800000">‘</span><span style="color: #000000">;
 
name char(</span>5<span style="color: #000000">)
egon </span>|alex |wxx  |<span style="color: #000000">
 
 
name varchar(</span>5<span style="color: #000000">)
1bytes</span>+egon|1bytes+alex|1bytes+wxx|

1.19 枚举类型与集合类型

<span style="color: #000000">create table employee(
    id int,
    name char(</span>10<span style="color: #000000">),
    sex enum(</span><span style="color: #800000">‘</span><span style="color: #800000">male</span><span style="color: #800000">‘</span>,<span style="color: #800000">‘</span><span style="color: #800000">female</span><span style="color: #800000">‘</span>,<span style="color: #800000">‘</span><span style="color: #800000">other</span><span style="color: #800000">‘</span><span style="color: #000000">),
    hobbies set(</span><span style="color: #800000">‘</span><span style="color: #800000">play</span><span style="color: #800000">‘</span>,<span style="color: #800000">‘</span><span style="color: #800000">eat</span><span style="color: #800000">‘</span>,<span style="color: #800000">‘</span><span style="color: #800000">music</span><span style="color: #800000">‘</span>,<span style="color: #800000">‘</span><span style="color: #800000">read</span><span style="color: #800000">‘</span><span style="color: #000000">)
);
 
insert into employee values
(</span>1,<span style="color: #800000">‘</span><span style="color: #800000">egon</span><span style="color: #800000">‘</span>,<span style="color: #800000">‘</span><span style="color: #800000">male</span><span style="color: #800000">‘</span>,<span style="color: #800000">‘</span><span style="color: #800000">music,read</span><span style="color: #800000">‘</span><span style="color: #000000">);
 
insert into employee values
(</span>2,<span style="color: #800000">‘</span><span style="color: #800000">alex</span><span style="color: #800000">‘</span>,<span style="color: #800000">‘</span><span style="color: #800000">xxxx</span><span style="color: #800000">‘</span>,<span style="color: #800000">‘</span><span style="color: #800000">music,read</span><span style="color: #800000">‘</span>);

多线程与MySQL（十）

标签：括号活动 software 用户态 release wait 系统设置 mysqld i/o

多线程与MySQL（十）

1.3 信号量Semaphore

1.4 Event事件

1.5 定时器

1.6 线程queue

1.7 进程池线程池

1.7.1 同步调用示例：

1.7.2 异步调用示例：

1.7.3 线程池

1.8 协程

1.8.1 串行执行

1.8.2 基于yield并发执行

1.9 greenlet模块

1.10 gevent模块

1.11 MySQL数据库相关概念

1.11.1 mysql是什么

1.11.2 数据库管理软件分类

1.11.3 下载安装

1.11.3.1 Linux版本

1.11.3.2 Window版本

1.12 重置密码

1.12.1 设置密码

1.12.2 重置密码

1.13 统一字符编码

1.14 初识SQL

1.14.1 操作文件夹（库）

1.14.1.1 增

1.14.1.2 查

1.14.1.3 改

1.14.1.4 删

1.14.2 操作文件（表）

1.14.2.1 查看当前所在的文件夹:

1.14.2.2 切换文件夹：

1.14.2.3 增

1.14.2.4 查

1.14.2.5 改

1.14.2.6 删

1.14.3 操作文件的内容（记录）

1.14.3.1 增

1.14.3.2 查

1.14.3.3 改

1.14.3.4 删

1.15 存储引擎

1.16 数值类型

1.16.1 整型(默认有符号)

1.16.2 浮点型

1.17 日期类型

1.18 字符类型

1.19 枚举类型与集合类型

人气教程排行