Flask Test

Consider a complex Flask application that uses an application factory pattern for scalability and flexibility. The application also utilizes global variables to manage configurations across different parts of the app. Review the following pseudo-code, which illustrates a portion of this application where an issue with application context might arise when deploying:

In this scenario, where the application is configured to run with multiple threads, what is the potential issue that could arise when processing multiple requests concurrently?

A: The db_connection in g might be shared across requests leading to data integrity issues.
B: The USE_CACHE configuration might reset to its default value in between requests.
C: Multiple threads might cause the application to crash due to improper locking mechanisms.
D: There will be no issues as Flask naturally handles application contexts per request in a thread-safe manner.
E: The configuration change in current_app.config['USE_CACHE'] will not be visible to the request handlers.

Examine the advanced Flask application setup below which uses an application factory pattern and is intended to handle multiple user requests simultaneously using threading. The developer has configured an endpoint to perform data processing based on user inputs and global settings. However, the application might exhibit unexpected behavior due to its handling of the Flask context and multithreading. Your task is to determine the output of this setup under concurrent requests.

The pseudo-code for the Flask application is as follows:

In this code, the threads are launched almost simultaneously. Thread1 executes a POST request to /set_cache, and Thread2 executes a GET request to /get_data. What is the likely output of Thread2 when it runs concurrently with Thread1?

A: "Using Cache"
B: "Not Using Cache"
C: The output is non-deterministic, depending on the execution timing of Thread1 and Thread2.
D: A Flask RuntimeError due to the application context being improperly managed.
E: No response due to a deadlock in resource access between the threads.

What will the following Python code output?

The function high_sess should compute the highest number of events per session of each user in the database by reading a comma-separated value input file of session data. The result should be returned from the function as a dictionary. The first column of each line in the input file is expected to contain the user’s name represented as a string. The second column is expected to contain an integer representing the events in a session. Here is an example input file:

Tony,10
Stark,12
Black,25
Your program should ignore a non-conforming line like this one.
Stark,3
Widow,6
Widow,14

The resulting return value for this file should be the following dictionary: { 'Stark':12, 'Black':25, 'Tony':10, 'Widow':14 }

What should replace the CODE TO FILL line to complete the function?

Below are code lines to create a Python function. Ignoring indentation, what lines should be used and in what order for the following function to be complete:

Consider the following Python code:

In the above code, recursive_search is a function that takes a dictionary (data) and a target key (target) as arguments. It searches for the target key within the dictionary, which could potentially have nested dictionaries and lists as values, and returns the value associated with the target key. If the target key is not found, it returns None.

nested_dict is a dictionary that contains multiple levels of nested dictionaries and lists. The recursive_search function is then called with nested_dict as the data and 'target_key' as the target.

What will the output be after executing the above code?

What does the below function ‘fun’ does?

A: Sum of digits of the number passed to fun.
B: Number of digits of the number passed to fun.
C: 0 if the number passed to fun is divisible by 10. 1 otherwise.
D: Sum of all digits number passed to fun except for the last digit.