PCPP2 Practice Test 3 — 10 Questions

Question 1

When using the multiprocessing module, why is it recommended to use a Manager object instead of a standard dictionary to share data between processes?

Accepted Answer

It ensures the dictionary is synchronized between processes.. A manager process is created to host the objects, allowing them to be shared safely between different processes using proxy objects.

Answer

It is faster than standard dictionaries.

Answer

It is the only way to store strings.

Answer

It removes the need for locks.

Answer

It allows local storage of values.

Question 2

Which PyMongo method should be used to update a single document if you want to modify specific fields without replacing the entire document?

Accepted Answer

update_one. The update_one method with the $set operator allows updating specific fields.

Answer

upsert

Answer

save

Answer

replace_one

Answer

update_many

Question 3

You are writing a Python script that needs to perform heavy I/O-bound tasks concurrently. Which module should you prioritize to minimize the overhead of global interpreter lock (GIL) contention?

Accepted Answer

threading. The threading module is ideal for I/O-bound tasks as it releases the GIL during blocking operations, whereas multiprocessing is better for CPU-bound tasks.

Answer

queue

Answer

subprocess

Answer

asyncio

Answer

multiprocessing

Question 4

Which TWO of the following scenarios are best suited for the subprocess module?

Accepted Answer

Running an external C++ executable.. Subprocess is intended for executing external binaries and interacting with their system streams.

Answer

Sharing memory between Python threads.

Answer

Managing internal thread pools.

Answer

Parallelizing Python functions.

Question 5

Which THREE of the following are common characteristics of the Observer pattern?

Accepted Answer

Automatic notification when the subject's state changes. One-to-many relationship, event notification, and loose coupling are key.

Answer

Observers are forced to be synchronous

Answer

The subject is tightly coupled to the concrete observers

Question 6

In the context of the threading module, what does the daemon flag do when set to True?

Accepted Answer

It causes the thread to exit when the main process exits.. Daemon threads exit automatically when the main program finishes.

Answer

It increases the thread's priority.

Answer

It prevents the thread from being interrupted.

Answer

It allows the thread to be killed by the OS.

Answer

It ensures the thread completes before the program exits.

Question 7

In pytest, how can you skip a test based on the operating system platform?

Accepted Answer

@pytest.mark.skipif(sys.platform == 'win32'). The @pytest.mark.skipif decorator allows for conditional skipping based on expressions like sys.platform.

Answer

pytest.ignore_if(platform='win32')

Answer

pytest.skip_on('win32')

Answer

@pytest.skip(os='win32')

Question 8

You are using SQLAlchemy's relationship() function. What does 'back_populates' achieve?

Accepted Answer

It synchronizes the two sides of the relationship in Python memory.. It links two sides of a relationship so that changes in one are reflected in the other via the session's identity map.

Answer

It improves query performance.

Answer

It automatically cascades deletes.

Answer

It forces a database level foreign key constraint.

Question 9

Which TWO of the following pytest command-line options allow for filtering which tests are run?

Accepted Answer

-m. -k allows filtering by substring and -m allows filtering by markers.

Answer

-v

Answer

-q

Answer

-s

Question 10

When using 'unittest.mock.MagicMock', what happens when you access an attribute that hasn't been defined?

Accepted Answer

It returns a new MagicMock instance.. MagicMock instances automatically create new MagicMock objects when you access previously undefined attributes.

Answer

It returns None.

Answer

It returns the string 'undefined'.

Answer

It raises an AttributeError.