Create multithreading.md

Author: C-Stevens

doc/multithreading.md

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+[<-- Return to index](../README.md)
+# Multithreading
+
+### How is multitasking accomplished?
+#### PHP
+By extending the [`Thread`](https://secure.php.net/manual/en/class.thread.php) class in the [pthreads API](https://secure.php.net/manual/en/intro.pthreads.php). It should be noted that by most defaults, PHP will be compiled as thread-safe and without pthreads. It requires a non-negligible amount of work to both recompile or obtain a version of PHP will threading enabled, and the pthreads API installed.
+#### Python
+By subclassing the [`Thread`](https://docs.python.org/3.6/library/threading.html#thread-objects) class from the [threading library](https://docs.python.org/3.6/library/threading.html#), which is native to Python.
+
+### How do threads or thread-like abilities work?
+#### PHP
+Parallel threading in PHP is less elegant than in Python, but ultimately just as functional. A parallel threading system in a basic form can look something like this:
+```php
+<?php
+    class myThread extends Thread {
+        private $id;
+        public function __construct($id) {
+            $this->id = $id;
+        }
+        public function run() {
+            $sleepTime = mt_rand(1, 5);
+            print "Thread with id ".$id."sleeping for ".$sleepTime." seconds";
+            sleep($sleepTime);
+            print "Thread with id ".$id." is ending";
+        }
+    }
+    
+    $threads = array();
+    foreach(range(0, 10) as $i) {
+        $threads[] = new myThread($i);
+    }
+    
+    foreach($threads as $t) {
+        $t->run();
+    }
+?>
+```
+
+#### Python
+Python's threading capabilities are dense and very well documented. A basic parallel threading system can look something like this:
+```python
+import time
+import random
+from threading import Thread
+
+def myThreadedMethod(id):
+    sleepTime = random.randint(1, 5)
+    print("Thread with id %d is sleeping for %d seconds"%(id, sleepTime))
+    time.sleep(sleepTime)
+    print("Thread with id %d is ending"%(id))
+
+for i in range(0, 10):
+    t = Thread(target=myThreadedMethod, args=(i,))
+    t.start()
+```
+Which will output:
+```
+Thread with id 0 is sleeping for 2 seconds
+Thread with id 1 is sleeping for 3 seconds
+Thread with id 2 is sleeping for 5 seconds
+Thread with id 3 is sleeping for 5 seconds
+Thread with id 4 is sleeping for 3 seconds
+Thread with id 5 is sleeping for 2 seconds
+Thread with id 6 is sleeping for 5 seconds
+Thread with id 7 is sleeping for 2 seconds
+Thread with id 8 is sleeping for 2 seconds
+Thread with id 9 is sleeping for 1 seconds
+
+Thread with id 9 is ending
+Thread with id 0 is ending
+Thread with id 5 is ending
+Thread with id 8 is ending
+Thread with id 7 is ending
+Thread with id 1 is ending
+Thread with id 4 is ending
+Thread with id 2 is ending
+Thread with id 3 is ending
+Thread with id 6 is ending
+```
+Note how the threads end at the end of their execution, not necessarily in the same order they were spawned. This demonstrates how all threads were running in parallel.