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Threading, Introspection

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Jure Šorn 4 years ago
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      README.md
  2. 53
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53
README.md
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@ -2050,19 +2050,19 @@ from threading import Thread, RLock, Semaphore, Event, Barrier
### Thread
```python
<Thread> = Thread(target=<function>) # Use `args=<collection>` to set arguments.
<Thread>.start() # Starts the thread.
<bool> = <Thread>.is_alive() # Checks if thread has finished executing.
<Thread>.join() # Waits for thread to finish.
<Thread> = Thread(target=<function>) # Use `args=<collection>` to set arguments.
<Thread>.start() # Starts the thread.
<bool> = <Thread>.is_alive() # Checks if thread has finished executing.
<Thread>.join() # Waits for thread to finish.
```
* **Use `'kwargs=<dict>'` to pass keyword arguments to the function.**
* **Use `'daemon=True'`, or the program will not be able to exit while the thread is alive.**
### Lock
```python
<lock> = RLock() # Lock that can only be released by the owner.
<lock>.acquire() # Waits for lock to be available.
<lock>.release() # Makes lock available again.
<lock> = RLock() # Lock that can only be released by the owner.
<lock>.acquire() # Waits for lock to be available.
<lock>.release() # Makes lock available again.
```
#### Or:
@ -2074,24 +2074,27 @@ with lock:
### Semaphore, Event, Barrier
```python
<Semaphore> = Semaphore(value=1) # Lock that can be acquired by 'value' threads at once.
<Event> = Event() # Method wait() blocks until set() is called.
<Barrier> = Barrier(n_times) # Method wait() blocks until it's called 'n_times'.
<Semaphore> = Semaphore(value=1) # Lock that can be acquired by 'value' threads.
<Event> = Event() # Method wait() blocks until set() is called.
<Barrier> = Barrier(n_times) # Method wait() blocks until it's called n_times.
```
### Thread Pool Executor
**Object that manages thread execution.**
```python
from concurrent.futures import ThreadPoolExecutor
with ThreadPoolExecutor(max_workers=None) as executor: # Does not exit until done.
<iter> = executor.map(lambda x: x + 1, range(3)) # (1, 2, 3)
<iter> = executor.map(lambda x, y: x + y, 'abc', '123') # ('a1', 'b2', 'c3')
<Future> = executor.submit(<function> [, <arg_1>, ...]) # Also visible outside block.
```
#### Future:
```python
<bool> = <Future>.done() # Checks if thread has finished executing.
<obj> = <Future>.result() # Waits for thread to finish and returns result.
<Exec> = ThreadPoolExecutor([max_workers]) # Use max_workers to limit the number of threads.
<Exec>.shutdown(wait=True) # Or: `with ThreadPoolExecutor() as executor: …`
```
```python
<iter> = <Exec>.map(<func>, <args_1>, ...) # A multithreaded and non-lazy map().
<Futr> = <Exec>.submit(<func>, <arg_1>, ...) # Starts a thread and returns its Future object.
<bool> = <Futr>.done() # Checks if thread has finished executing.
<obj> = <Futr>.result() # Waits for thread to finish and returns result.
```
### Queue
@ -2102,10 +2105,10 @@ from queue import Queue
```
```python
<Queue>.put(<el>) # Blocks until queue stops being full.
<Queue>.put_nowait(<el>) # Raises queue.Full exception if full.
<el> = <Queue>.get() # Blocks until queue stops being empty.
<el> = <Queue>.get_nowait() # Raises queue.Empty exception if empty.
<Queue>.put(<el>) # Blocks until queue stops being full.
<Queue>.put_nowait(<el>) # Raises queue.Full exception if full.
<el> = <Queue>.get() # Blocks until queue stops being empty.
<el> = <Queue>.get_nowait() # Raises queue.Empty exception if empty.
```
@ -2155,10 +2158,10 @@ delattr(<object>, '<attr_name>') # Equivalent to `del <object>.<attr_n
### Parameters
```python
from inspect import signature
<sig> = signature(<function>)
no_of_params = len(<sig>.parameters)
param_names = list(<sig>.parameters.keys())
param_kinds = [a.kind for a in <sig>.parameters.values()]
<sig> = signature(<function>) # Signature object of the function.
<dict> = <sig>.parameters # Dict of function's parameters.
<str> = <param>.name # Prameter's name.
<memb> = <param>.kind # Member of ParameterKind enum.
```

53
index.html
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@ -1835,19 +1835,19 @@ CompletedProcess(args=[<span class="hljs-string">'bc'</span>, <span class="hljs-
</code></pre></div>
<div><h3 id="thread">Thread</h3><pre><code class="python language-python hljs">&lt;Thread&gt; = Thread(target=&lt;function&gt;) <span class="hljs-comment"># Use `args=&lt;collection&gt;` to set arguments.</span>
&lt;Thread&gt;.start() <span class="hljs-comment"># Starts the thread.</span>
&lt;bool&gt; = &lt;Thread&gt;.is_alive() <span class="hljs-comment"># Checks if thread has finished executing.</span>
&lt;Thread&gt;.join() <span class="hljs-comment"># Waits for thread to finish.</span>
<div><h3 id="thread">Thread</h3><pre><code class="python language-python hljs">&lt;Thread&gt; = Thread(target=&lt;function&gt;) <span class="hljs-comment"># Use `args=&lt;collection&gt;` to set arguments.</span>
&lt;Thread&gt;.start() <span class="hljs-comment"># Starts the thread.</span>
&lt;bool&gt; = &lt;Thread&gt;.is_alive() <span class="hljs-comment"># Checks if thread has finished executing.</span>
&lt;Thread&gt;.join() <span class="hljs-comment"># Waits for thread to finish.</span>
</code></pre></div>
<ul>
<li><strong>Use <code class="python hljs"><span class="hljs-string">'kwargs=&lt;dict&gt;'</span></code> to pass keyword arguments to the function.</strong></li>
<li><strong>Use <code class="python hljs"><span class="hljs-string">'daemon=True'</span></code>, or the program will not be able to exit while the thread is alive.</strong></li>
</ul>
<div><h3 id="lock">Lock</h3><pre><code class="python language-python hljs">&lt;lock&gt; = RLock() <span class="hljs-comment"># Lock that can only be released by the owner.</span>
&lt;lock&gt;.acquire() <span class="hljs-comment"># Waits for lock to be available.</span>
&lt;lock&gt;.release() <span class="hljs-comment"># Makes lock available again.</span>
<div><h3 id="lock">Lock</h3><pre><code class="python language-python hljs">&lt;lock&gt; = RLock() <span class="hljs-comment"># Lock that can only be released by the owner.</span>
&lt;lock&gt;.acquire() <span class="hljs-comment"># Waits for lock to be available.</span>
&lt;lock&gt;.release() <span class="hljs-comment"># Makes lock available again.</span>
</code></pre></div>
<div><h4 id="or-1">Or:</h4><pre><code class="python language-python hljs">lock = RLock()
@ -1855,31 +1855,32 @@ CompletedProcess(args=[<span class="hljs-string">'bc'</span>, <span class="hljs-
...
</code></pre></div>
<div><h3 id="semaphoreeventbarrier">Semaphore, Event, Barrier</h3><pre><code class="python language-python hljs">&lt;Semaphore&gt; = Semaphore(value=<span class="hljs-number">1</span>) <span class="hljs-comment"># Lock that can be acquired by 'value' threads at once.</span>
&lt;Event&gt; = Event() <span class="hljs-comment"># Method wait() blocks until set() is called.</span>
&lt;Barrier&gt; = Barrier(n_times) <span class="hljs-comment"># Method wait() blocks until it's called 'n_times'.</span>
<div><h3 id="semaphoreeventbarrier">Semaphore, Event, Barrier</h3><pre><code class="python language-python hljs">&lt;Semaphore&gt; = Semaphore(value=<span class="hljs-number">1</span>) <span class="hljs-comment"># Lock that can be acquired by 'value' threads.</span>
&lt;Event&gt; = Event() <span class="hljs-comment"># Method wait() blocks until set() is called.</span>
&lt;Barrier&gt; = Barrier(n_times) <span class="hljs-comment"># Method wait() blocks until it's called n_times.</span>
</code></pre></div>
<div><h3 id="threadpoolexecutor">Thread Pool Executor</h3><pre><code class="python language-python hljs"><span class="hljs-keyword">from</span> concurrent.futures <span class="hljs-keyword">import</span> ThreadPoolExecutor
<span class="hljs-keyword">with</span> ThreadPoolExecutor(max_workers=<span class="hljs-keyword">None</span>) <span class="hljs-keyword">as</span> executor: <span class="hljs-comment"># Does not exit until done.</span>
&lt;iter&gt; = executor.map(<span class="hljs-keyword">lambda</span> x: x + <span class="hljs-number">1</span>, range(<span class="hljs-number">3</span>)) <span class="hljs-comment"># (1, 2, 3)</span>
&lt;iter&gt; = executor.map(<span class="hljs-keyword">lambda</span> x, y: x + y, <span class="hljs-string">'abc'</span>, <span class="hljs-string">'123'</span>) <span class="hljs-comment"># ('a1', 'b2', 'c3')</span>
&lt;Future&gt; = executor.submit(&lt;function&gt; [, &lt;arg_1&gt;, ...]) <span class="hljs-comment"># Also visible outside block.</span>
<div><h3 id="threadpoolexecutor">Thread Pool Executor</h3><p><strong>Object that manages thread execution.</strong></p><pre><code class="python language-python hljs"><span class="hljs-keyword">from</span> concurrent.futures <span class="hljs-keyword">import</span> ThreadPoolExecutor
</code></pre></div>
<div><h4 id="future">Future:</h4><pre><code class="python language-python hljs">&lt;bool&gt; = &lt;Future&gt;.done() <span class="hljs-comment"># Checks if thread has finished executing.</span>
&lt;obj&gt; = &lt;Future&gt;.result() <span class="hljs-comment"># Waits for thread to finish and returns result.</span>
</code></pre></div>
<pre><code class="python language-python hljs">&lt;Exec&gt; = ThreadPoolExecutor([max_workers]) <span class="hljs-comment"># Use max_workers to limit the number of threads.</span>
&lt;Exec&gt;.shutdown(wait=<span class="hljs-keyword">True</span>) <span class="hljs-comment"># Or: `with ThreadPoolExecutor() as executor: …`</span>
</code></pre>
<pre><code class="python language-python hljs">&lt;iter&gt; = &lt;Exec&gt;.map(&lt;func&gt;, &lt;args_1&gt;, ...) <span class="hljs-comment"># A multithreaded and non-lazy map().</span>
&lt;Futr&gt; = &lt;Exec&gt;.submit(&lt;func&gt;, &lt;arg_1&gt;, ...) <span class="hljs-comment"># Starts a thread and returns its Future object.</span>
&lt;bool&gt; = &lt;Futr&gt;.done() <span class="hljs-comment"># Checks if thread has finished executing.</span>
&lt;obj&gt; = &lt;Futr&gt;.result() <span class="hljs-comment"># Waits for thread to finish and returns result.</span>
</code></pre>
<div><h3 id="queue">Queue</h3><p><strong>A thread-safe FIFO queue. For LIFO queue use LifoQueue.</strong></p><pre><code class="python language-python hljs"><span class="hljs-keyword">from</span> queue <span class="hljs-keyword">import</span> Queue
&lt;Queue&gt; = Queue(maxsize=<span class="hljs-number">0</span>)
</code></pre></div>
<pre><code class="python language-python hljs">&lt;Queue&gt;.put(&lt;el&gt;) <span class="hljs-comment"># Blocks until queue stops being full.</span>
&lt;Queue&gt;.put_nowait(&lt;el&gt;) <span class="hljs-comment"># Raises queue.Full exception if full.</span>
&lt;el&gt; = &lt;Queue&gt;.get() <span class="hljs-comment"># Blocks until queue stops being empty.</span>
&lt;el&gt; = &lt;Queue&gt;.get_nowait() <span class="hljs-comment"># Raises queue.Empty exception if empty.</span>
<pre><code class="python language-python hljs">&lt;Queue&gt;.put(&lt;el&gt;) <span class="hljs-comment"># Blocks until queue stops being full.</span>
&lt;Queue&gt;.put_nowait(&lt;el&gt;) <span class="hljs-comment"># Raises queue.Full exception if full.</span>
&lt;el&gt; = &lt;Queue&gt;.get() <span class="hljs-comment"># Blocks until queue stops being empty.</span>
&lt;el&gt; = &lt;Queue&gt;.get_nowait() <span class="hljs-comment"># Raises queue.Empty exception if empty.</span>
</code></pre>
<div><h2 id="operator"><a href="#operator" name="operator">#</a>Operator</h2><p><strong>Module of functions that provide the functionality of operators.</strong></p><pre><code class="python language-python hljs"><span class="hljs-keyword">from</span> operator <span class="hljs-keyword">import</span> add, sub, mul, truediv, floordiv, mod, pow, neg, abs
<span class="hljs-keyword">from</span> operator <span class="hljs-keyword">import</span> eq, ne, lt, le, gt, ge
@ -1913,10 +1914,10 @@ delattr(&lt;object&gt;, <span class="hljs-string">'&lt;attr_name&gt;'</span>)
</code></pre></div>
<div><h3 id="parameters-1">Parameters</h3><pre><code class="python language-python hljs"><span class="hljs-keyword">from</span> inspect <span class="hljs-keyword">import</span> signature
&lt;sig&gt; = signature(&lt;function&gt;)
no_of_params = len(&lt;sig&gt;.parameters)
param_names = list(&lt;sig&gt;.parameters.keys())
param_kinds = [a.kind <span class="hljs-keyword">for</span> a <span class="hljs-keyword">in</span> &lt;sig&gt;.parameters.values()]
&lt;sig&gt; = signature(&lt;function&gt;) <span class="hljs-comment"># Signature object of the function.</span>
&lt;dict&gt; = &lt;sig&gt;.parameters <span class="hljs-comment"># Dict of function's parameters.</span>
&lt;str&gt; = &lt;param&gt;.name <span class="hljs-comment"># Prameter's name.</span>
&lt;memb&gt; = &lt;param&gt;.kind <span class="hljs-comment"># Member of ParameterKind enum.</span>
</code></pre></div>
<div><h2 id="metaprograming"><a href="#metaprograming" name="metaprograming">#</a>Metaprograming</h2><p><strong>Code that generates code.</strong></p><div><h3 id="type-1">Type</h3><p><strong>Type is the root class. If only passed an object it returns its type (class). Otherwise it creates a new class.</strong></p><pre><code class="python language-python hljs">&lt;class&gt; = type(<span class="hljs-string">'&lt;class_name&gt;'</span>, &lt;parents_tuple&gt;, &lt;attributes_dict&gt;)</code></pre></div></div>

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