PCPP2 Practice Test 15 — 15 Questions

Question 1

In a multi-threaded Python server, why is it discouraged to share a single socket object across multiple threads without synchronization?

Accepted Answer

Concurrent access can lead to interleaved or corrupted data streams.. Socket operations are generally thread-safe in CPython, but overlapping operations on the same file descriptor can lead to interleaved data or corrupted state.

Answer

Python's GIL prevents concurrent socket access.

Answer

Sockets are not picklable.

Answer

The socket module raises a RuntimeError for concurrent usage.

Question 2

You need to mock an object that is imported into a module. Which patch strategy correctly replaces the object where it is used?

Accepted Answer

Patch the object at the import location within the module being tested.. You must patch the object in the namespace where it is imported (the destination), not where it is defined, to ensure the replacement takes effect.

Answer

Use a global variable to override the module import.

Answer

Patch the object at its definition location.

Answer

Modify sys.modules directly.

Question 3

When using 'unittest', how do you ensure that a teardown method runs even if the test method raises an exception?

Accepted Answer

The framework automatically calls tearDown().. The 'tearDown' method is guaranteed to run by the unittest framework regardless of the test outcome, assuming setup succeeded.

Answer

You must check 'self.failureException'.

Answer

You must use the 'addCleanup' method.

Answer

Use a try-finally block inside the test method.

Question 4

Which THREE of the following are true regarding the use of 'unittest.mock.patch'?

Accepted Answer

It can be used as a context manager.. Patching can be used as a decorator, a context manager, or manually with 'start' and 'stop'.

Answer

It automatically deletes the original object.

Answer

It is only available for local modules.

Question 5

Which socket method is used to bind a socket to a specific address and port?

Accepted Answer

socket.bind(). The bind() method associates a socket with a specific address and port tuple.

Answer

socket.accept()

Answer

socket.connect()

Answer

socket.listen()

Question 6

Which THREE of the following options can be used with socket.setsockopt()?

Accepted Answer

socket.SO_KEEPALIVE. SO_REUSEADDR, SO_KEEPALIVE, and TCP_NODELAY are standard options supported by most systems.

Answer

socket.TCP_BUFFER_SIZE

Answer

socket.SO_MAX_CONNECTIONS

Question 7

When spawning processes on Windows, what is the default start method used by the multiprocessing module?

Accepted Answer

spawn. The 'spawn' method is the default on Windows.

Answer

thread

Answer

exec

Answer

forkserver

Answer

fork

Question 8

What is the result of using a Pipe to communicate between two processes if both processes attempt to write to the same end simultaneously?

Accepted Answer

The data may be corrupted or interleaved.. Data corruption can occur as the messages may become interleaved or mangled.

Answer

It raises an exception.

Answer

The OS serializes the writes automatically.

Answer

The write blocks until the other finishes.

Answer

One of the writes is silently dropped.

Question 9

When using the 'unittest' framework, which method is executed exactly once before any test methods in a class are run?

Accepted Answer

setUpClass. The 'setUpClass' method is a class method that runs once before all tests in the class, whereas 'setUp' runs before each individual test.

Answer

setUp

Answer

pre_test

Answer

init

Question 10

Which function in the socket module is used to convert a 32-bit integer from host byte order to network byte order?

Accepted Answer

socket.htonl(). htonl() stands for Host to Network Long, converting 32-bit integers for network transmission.

Answer

socket.ntohl()

Answer

socket.htons()

Answer

socket.inet_aton()

Question 11

When using select.select(inputs, outputs, exceptions), what does the 'outputs' list signify?

Accepted Answer

Sockets that are ready to send data without blocking.. The 'outputs' list contains sockets that are monitored for readiness to accept data for writing without blocking.

Answer

Sockets that are closed for writing.

Answer

Sockets that have finished writing.

Answer

Sockets that have received an interrupt signal.

Question 12

Which object would you use to share a simple integer between processes that is safe for concurrent access?

Accepted Answer

multiprocessing.Value. multiprocessing.Value is designed specifically to share single values between processes with a lock.

Answer

list

Answer

threading.Lock

Answer

global variable

Answer

multiprocessing.Queue

Question 13

Which TWO of the following are key benefits of using the multiprocessing.Pool class?

Accepted Answer

Automatic process creation and management.. Pools simplify process management and provide convenient result retrieval mechanisms.

Answer

Higher performance for I/O tasks than threads.

Answer

Guaranteed memory sharing between processes.

Answer

Automatic elimination of the GIL.

Question 14

Which THREE of the following are true about the 'subprocess' module's interaction with the operating system?

Accepted Answer

It can connect to standard input/output pipes.. Subprocess allows control over pipes, environments, and working directories for child processes.

Answer

It automatically cleans up zombie processes.

Answer

It allows direct manipulation of the parent process's memory.

Question 15

Why should you use a 'with' statement when using a Lock?

Accepted Answer

It automatically handles lock acquisition and release.. It automatically acquires and releases the lock, ensuring it is released even if an exception occurs.

Answer

It allows multiple threads to acquire the lock.

Answer

It increases the performance of the lock.

Answer

It creates a thread-safe environment.

Answer

It prevents the lock from being garbage collected.