Number of file handles does not scale with number of Consumer(s)

[anthony-vaticlabs]

Description

The number of open file handles is not proportional with the number of Consumer(s) in a process. I have a simple example where I create N Consumer(s) in a loop. For each N in [1...10] I run lsof | awk '{print $4}' | sort | uniq -c | sort -n to examine the number of open file handles. Below is a paste of the number of file handles for each N [1...10]

1: 531
2: 1386
3: 1848
4: 4068
5: 5896
6: 8046
7: 10518
8: 13320
9: 16443
10: 19890

Furthermore, why is it that > 500 file handles need to be opened for one Consumer?

How to reproduce

import time
import uuid

from confluent_kafka import Consumer, Producer, TopicPartition
from confluent_kafka.admin import AdminClient, NewTopic


if __name__ == "__main__":
    conf = {"bootstrap.servers":  "INSERT_ANY_BOOTSTRAP",
            "enable.auto.commit": False,
            "group.id": "kafka-test" + str(uuid.uuid1()),
            }

    tracker = []

    for i in range(10):
        topic = str(uuid.uuid1()) # can be any dummy topic name
        consumer = Consumer(**conf)
        consumer.subscribe([topic])
        tracker.append(consumer)

    while True:
        time.sleep(5)

with
lsof | awk '{print $4}' | sort | uniq -c | sort -n

Checklist

Please provide the following information:

• [1.9.0 and 1.9.0 ] confluent-kafka-python and librdkafka version (confluent_kafka.version() and confluent_kafka.libversion()):
• Apache Kafka broker version:
• Client configuration: {...}
• Operating system:
• Provide client logs (with 'debug': '..' as necessary)
• Provide broker log excerpts
• Critical issue

[mhowlett]

i don't know. each instance is completely independent.

[MSeal]

I wonder if this is related to the root cause of #1361