Partition count strategy in Kafka - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this Kafka partition assignment code?

Consider a Kafka topic with 3 partitions and 2 consumers in a consumer group. Given the following partition assignment logic, what partitions will each consumer receive?

Kafka

partitions = [0, 1, 2]
consumers = ['consumer1', 'consumer2']
assignment = {c: [] for c in consumers}
for i, p in enumerate(partitions):
    assignment[consumers[i % len(consumers)]].append(p)
print(assignment)

A {'consumer1': [0], 'consumer2': [1, 2]}

B {'consumer1': [1, 2], 'consumer2': [0]}

C {'consumer1': [0, 2], 'consumer2': [1]}

D {'consumer1': [0, 1, 2], 'consumer2': []}

💡 Hint

Partitions are assigned in a round-robin way based on the index modulo the number of consumers.

The code assigns partitions 0 and 2 to consumer1 because 0 % 2 = 0 and 2 % 2 = 0, and partition 1 to consumer2 because 1 % 2 = 1.

🧠 Conceptual

intermediate

How does increasing partition count affect Kafka topic throughput?

Which statement best describes the effect of increasing the number of partitions in a Kafka topic on throughput?

A Increasing partitions always decreases throughput due to overhead.

B Increasing partitions can increase throughput by allowing more parallelism.

C Partition count has no effect on throughput.

D Increasing partitions reduces throughput because consumers get fewer messages.

💡 Hint

Think about how partitions allow multiple consumers to read in parallel.

More partitions allow more consumers to read in parallel, increasing throughput, but too many partitions can add overhead.

🔧 Debug

advanced

Identify the error in this partition assignment code snippet

What error will this Kafka partition assignment code raise?

Kafka

partitions = [0, 1, 2]
consumers = ['c1', 'c2']
assignment = {c: [] for c in consumers}
for i in range(len(partitions)+1):
    assignment[consumers[i % len(consumers)]].append(partitions[i])
print(assignment)

A IndexError: list index out of range

B KeyError: 'c3'

C TypeError: unsupported operand type(s)

D No error, prints assignment correctly

💡 Hint

Check the loop range and how it accesses the partitions list.

The loop runs one iteration too many (len(partitions)+1), causing partitions[i] to access an invalid index.

📝 Syntax

advanced

Which option correctly defines a Kafka topic with 5 partitions using Kafka CLI?

Choose the correct Kafka CLI command to create a topic named 'logs' with 5 partitions.

A kafka-topics.sh --create --topic logs --partitions-count 5 --bootstrap-server localhost:9092

B kafka-topics.sh --create --topic logs --partition-count 5 --bootstrap-server localhost:9092

C kafka-topics.sh --create --topic logs --num-partitions 5 --bootstrap-server localhost:9092

D kafka-topics.sh --create --topic logs --partitions 5 --bootstrap-server localhost:9092

💡 Hint

Check the exact option name for partitions in Kafka CLI.

The correct option to specify partitions is '--partitions'. Other options are invalid and cause errors.

🚀 Application

expert

Calculate the number of partitions needed for a target throughput

You want to achieve a throughput of 1 million messages per second. Each partition can handle 100,000 messages per second. How many partitions should your Kafka topic have at minimum?

A 10

B 100

C 1,000

D 100,000

💡 Hint

Divide the target throughput by the capacity per partition.

1,000,000 / 100,000 = 10 partitions needed to meet the throughput.