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Python

Synchronized shared counter (by Eli Bendersky)

from multiprocessing import Process, Value, Lock

class Counter(object):

    def __init__(self, initval=0):
    
        self.val = Value('i', initval)
        self.lock = Lock()

    # end def __init__
    
    
    def increment(self):
    
        with self.lock:
            self.val.value += 1
        # end with

    # end def increment
    
    
    def value(self):
    
        with self.lock:
            return self.val.value
        # end with
        
    # end def value
    
# end class Counter


def func(counter):
    
    for i in range(50):
        time.sleep(0.01)
        counter.increment()
    # end for
    
# end def func


if __name__ == '__main__':

    counter = Counter(0)
    procs = [Process(target=func, args=(counter,)) for i in range(10)]

    for p in procs:
        p.start()
    # end for
    
    for p in procs:
        p.join()
    # end for

    print counter.value()
    
# end if
https://snipt.net/embed/c414c5899ad5d39d1989f6243bb8b254/
/raw/c414c5899ad5d39d1989f6243bb8b254/
c414c5899ad5d39d1989f6243bb8b254
python
Python
58
2019-07-16T10:01:03
True
False
False
Sep 17, 2013 at 09:07 AM
/api/public/snipt/81456/
synchronized-shared-counter-by-eli-bendersky
<table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><a href="#L-1"> 1</a> <a href="#L-2"> 2</a> <a href="#L-3"> 3</a> <a href="#L-4"> 4</a> <a href="#L-5"> 5</a> <a href="#L-6"> 6</a> <a href="#L-7"> 7</a> <a href="#L-8"> 8</a> <a href="#L-9"> 9</a> <a href="#L-10">10</a> <a href="#L-11">11</a> <a href="#L-12">12</a> <a href="#L-13">13</a> <a href="#L-14">14</a> <a href="#L-15">15</a> <a href="#L-16">16</a> <a href="#L-17">17</a> <a href="#L-18">18</a> <a href="#L-19">19</a> <a href="#L-20">20</a> <a href="#L-21">21</a> <a href="#L-22">22</a> <a href="#L-23">23</a> <a href="#L-24">24</a> <a href="#L-25">25</a> <a href="#L-26">26</a> <a href="#L-27">27</a> <a href="#L-28">28</a> <a href="#L-29">29</a> <a href="#L-30">30</a> <a href="#L-31">31</a> <a href="#L-32">32</a> <a href="#L-33">33</a> <a href="#L-34">34</a> <a href="#L-35">35</a> <a href="#L-36">36</a> <a href="#L-37">37</a> <a href="#L-38">38</a> <a href="#L-39">39</a> <a href="#L-40">40</a> <a href="#L-41">41</a> <a href="#L-42">42</a> <a href="#L-43">43</a> <a href="#L-44">44</a> <a href="#L-45">45</a> <a href="#L-46">46</a> <a href="#L-47">47</a> <a href="#L-48">48</a> <a href="#L-49">49</a> <a href="#L-50">50</a> <a href="#L-51">51</a> <a href="#L-52">52</a> <a href="#L-53">53</a> <a href="#L-54">54</a> <a href="#L-55">55</a> <a href="#L-56">56</a> <a href="#L-57">57</a> <a href="#L-58">58</a></pre></div></td><td class="code"><div class="highlight"><pre><span></span><span id="L-1"><a name="L-1"></a><span class="kn">from</span> <span class="nn">multiprocessing</span> <span class="kn">import</span> <span class="n">Process</span><span class="p">,</span> <span class="n">Value</span><span class="p">,</span> <span class="n">Lock</span> </span><span id="L-2"><a name="L-2"></a> </span><span id="L-3"><a name="L-3"></a><span class="k">class</span> <span class="nc">Counter</span><span class="p">(</span><span class="nb">object</span><span class="p">):</span> </span><span id="L-4"><a name="L-4"></a> </span><span id="L-5"><a name="L-5"></a> <span class="k">def</span> <span class="nf">__init__</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">initval</span><span class="o">=</span><span class="mi">0</span><span class="p">):</span> </span><span id="L-6"><a name="L-6"></a> </span><span id="L-7"><a name="L-7"></a> <span class="bp">self</span><span class="o">.</span><span class="n">val</span> <span class="o">=</span> <span class="n">Value</span><span class="p">(</span><span class="s1">&#39;i&#39;</span><span class="p">,</span> <span class="n">initval</span><span class="p">)</span> </span><span id="L-8"><a name="L-8"></a> <span class="bp">self</span><span class="o">.</span><span class="n">lock</span> <span class="o">=</span> <span class="n">Lock</span><span class="p">()</span> </span><span id="L-9"><a name="L-9"></a> </span><span id="L-10"><a name="L-10"></a> <span class="c1"># end def __init__</span> </span><span id="L-11"><a name="L-11"></a> </span><span id="L-12"><a name="L-12"></a> </span><span id="L-13"><a name="L-13"></a> <span class="k">def</span> <span class="nf">increment</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span> </span><span id="L-14"><a name="L-14"></a> </span><span id="L-15"><a name="L-15"></a> <span class="k">with</span> <span class="bp">self</span><span class="o">.</span><span class="n">lock</span><span class="p">:</span> </span><span id="L-16"><a name="L-16"></a> <span class="bp">self</span><span class="o">.</span><span class="n">val</span><span class="o">.</span><span class="n">value</span> <span class="o">+=</span> <span class="mi">1</span> </span><span id="L-17"><a name="L-17"></a> <span class="c1"># end with</span> </span><span id="L-18"><a name="L-18"></a> </span><span id="L-19"><a name="L-19"></a> <span class="c1"># end def increment</span> </span><span id="L-20"><a name="L-20"></a> </span><span id="L-21"><a name="L-21"></a> </span><span id="L-22"><a name="L-22"></a> <span class="k">def</span> <span class="nf">value</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span> </span><span id="L-23"><a name="L-23"></a> </span><span id="L-24"><a name="L-24"></a> <span class="k">with</span> <span class="bp">self</span><span class="o">.</span><span class="n">lock</span><span class="p">:</span> </span><span id="L-25"><a name="L-25"></a> <span class="k">return</span> <span class="bp">self</span><span class="o">.</span><span class="n">val</span><span class="o">.</span><span class="n">value</span> </span><span id="L-26"><a name="L-26"></a> <span class="c1"># end with</span> </span><span id="L-27"><a name="L-27"></a> </span><span id="L-28"><a name="L-28"></a> <span class="c1"># end def value</span> </span><span id="L-29"><a name="L-29"></a> </span><span id="L-30"><a name="L-30"></a><span class="c1"># end class Counter</span> </span><span id="L-31"><a name="L-31"></a> </span><span id="L-32"><a name="L-32"></a> </span><span id="L-33"><a name="L-33"></a><span class="k">def</span> <span class="nf">func</span><span class="p">(</span><span class="n">counter</span><span class="p">):</span> </span><span id="L-34"><a name="L-34"></a> </span><span id="L-35"><a name="L-35"></a> <span class="k">for</span> <span class="n">i</span> <span class="ow">in</span> <span class="nb">range</span><span class="p">(</span><span class="mi">50</span><span class="p">):</span> </span><span id="L-36"><a name="L-36"></a> <span class="n">time</span><span class="o">.</span><span class="n">sleep</span><span class="p">(</span><span class="mf">0.01</span><span class="p">)</span> </span><span id="L-37"><a name="L-37"></a> <span class="n">counter</span><span class="o">.</span><span class="n">increment</span><span class="p">()</span> </span><span id="L-38"><a name="L-38"></a> <span class="c1"># end for</span> </span><span id="L-39"><a name="L-39"></a> </span><span id="L-40"><a name="L-40"></a><span class="c1"># end def func</span> </span><span id="L-41"><a name="L-41"></a> </span><span id="L-42"><a name="L-42"></a> </span><span id="L-43"><a name="L-43"></a><span class="k">if</span> <span class="n">__name__</span> <span class="o">==</span> <span class="s1">&#39;__main__&#39;</span><span class="p">:</span> </span><span id="L-44"><a name="L-44"></a> </span><span id="L-45"><a name="L-45"></a> <span class="n">counter</span> <span class="o">=</span> <span class="n">Counter</span><span class="p">(</span><span class="mi">0</span><span class="p">)</span> </span><span id="L-46"><a name="L-46"></a> <span class="n">procs</span> <span class="o">=</span> <span class="p">[</span><span class="n">Process</span><span class="p">(</span><span class="n">target</span><span class="o">=</span><span class="n">func</span><span class="p">,</span> <span class="n">args</span><span class="o">=</span><span class="p">(</span><span class="n">counter</span><span class="p">,))</span> <span class="k">for</span> <span class="n">i</span> <span class="ow">in</span> <span class="nb">range</span><span class="p">(</span><span class="mi">10</span><span class="p">)]</span> </span><span id="L-47"><a name="L-47"></a> </span><span id="L-48"><a name="L-48"></a> <span class="k">for</span> <span class="n">p</span> <span class="ow">in</span> <span class="n">procs</span><span class="p">:</span> </span><span id="L-49"><a name="L-49"></a> <span class="n">p</span><span class="o">.</span><span class="n">start</span><span class="p">()</span> </span><span id="L-50"><a name="L-50"></a> <span class="c1"># end for</span> </span><span id="L-51"><a name="L-51"></a> </span><span id="L-52"><a name="L-52"></a> <span class="k">for</span> <span class="n">p</span> <span class="ow">in</span> <span class="n">procs</span><span class="p">:</span> </span><span id="L-53"><a name="L-53"></a> <span class="n">p</span><span class="o">.</span><span class="n">join</span><span class="p">()</span> </span><span id="L-54"><a name="L-54"></a> <span class="c1"># end for</span> </span><span id="L-55"><a name="L-55"></a> </span><span id="L-56"><a name="L-56"></a> <span class="k">print</span> <span class="n">counter</span><span class="o">.</span><span class="n">value</span><span class="p">()</span> </span><span id="L-57"><a name="L-57"></a> </span><span id="L-58"><a name="L-58"></a><span class="c1"># end if</span> </span></pre></div> </td></tr></table>
Python, multithreading