The ultimate guide to senior engineering interviews. Strategies developed by FAANG engineers on Python concurrency, multithreading, monitors, and event loops. Prep faster for top company questions.

Concurrency in Python is one of the most complex and advanced topics brought up during senior engineering interviews. Knowledge of concurrency and multithreading can put interviewees at a considerable advantage. This course lays the foundations of advanced concurrency and multithreading and explains concepts such as Monitors, Event Loops and Deferred Callbacks in depth. It also builds simple and complete solutions to popular concurrency problems that can be asked about in interviews like the Reader-Writer Problem and the Dining Philosopher Problem. While prior knowledge of concurrency is not required to follow through with this course, familiarity with the very basic Python would be helpful.

Python Concurrency for Senior Engineering Interviews

<div class="card">
# Miscellaneous Functions
<div class="ans">
The <code class="abtc">concurrent.futures</code> module provides two methods to wait for futures collectively. These are:

<ul>
<li>wait</li>
<li>as_completed</li>
</ul>

Let's discuss each with examples below.

## wait ( )
The <code class="mthd">wait()</code> method takes in an iterable consisting of futures. These futures could be futures returned from thread or process pools. Next, it takes a timeout value, which if elapsed will return from the <code class="mthd">wait()</code> call irrespective of how many futures have completed. The last argument is interesting and describes the strategy used to wait for the futures. It takes on the following values:

<ul>
<li> FIRST_COMPLETED </li>
<li> FIRST_EXCEPTION </li>
<li> ALL_COMPLETED </li>
</ul>

The <code class="mthd">wait()</code> call returns a value consisting of two sets. One set consists of futures that have completed or cancelled and the other consists of futures pending or running futures. Consider the snippet from the executable example below:


```python
 result = wait(lst, timeout=None, return_when='ALL_COMPLETED')

 print("completed futures count: " + str(len(result.done)) + " and uncompleted futures count: " +
 str(len(result.not_done)) + "\n")

```

The above lines demonstrate how we <code class="mthd">wait()</code> for all futures to complete and then print the counts of both the sets returned from the <code class="mthd">wait()</code> call. 
</div>

<div>
# Miscellaneous Functions
<div>
The <code>concurrent.futures</code> module provides two methods to wait for futures collectively. These are:

<ul>
<li>wait</li>
<li>as_completed</li>
</ul>

Let's discuss each with examples below.

## wait ( )
The <code>wait()</code> method takes in an iterable consisting of futures. These futures could be futures returned from thread or process pools. Next, it takes a timeout value, which if elapsed will return from the <code>wait()</code> call irrespective of how many futures have completed. The last argument is interesting and describes the strategy used to wait for the futures. It takes on the following values:

<ul>
<li> FIRST_COMPLETED </li>
<li> FIRST_EXCEPTION </li>
<li> ALL_COMPLETED </li>
</ul>

The <code>wait()</code> call returns a value consisting of two sets. One set consists of futures that have completed or cancelled and the other consists of futures pending or running futures. Consider the snippet from the executable example below:


```python
 result = wait(lst, timeout=None, return_when='ALL_COMPLETED')

 print("completed futures count: " + str(len(result.done)) + " and uncompleted futures count: " +
 str(len(result.not_done)) + "\n")

```

The above lines demonstrate how we <code>wait()</code> for all futures to complete and then print the counts of both the sets returned from the <code>wait()</code> call. 
</div>

This lesson demonstrates the use of various utility functions present in the concurrent module.

The Basics

Threading Module

Multiprocessing

Concurrent Package

Async.io

Global Interpreter Lock

Interview Practise Problems

The End

Miscellaneous Functions

Miscellaneous Functions

wait ( )