Deadlock in WriteBufferFromS3::waitForAllBackGroundTasks #48136
Description
This gets stuck:
INSERT INTO FUNCTION s3(..., 'CSV') PARTITION BY number SELECT * FROM numbers(3500)
where '...' is a url (with {_partition_id} wildcard in it) and access key.
For comparison, it works if we reduce 3500 to 3000:
INSERT INTO FUNCTION s3(..., 'CSV') PARTITION BY number SELECT * FROM numbers(3000)
This has something to do with the global thread pool size. With the following server settings:
max_thread_pool_size: 80
background_schedule_pool_size: 2
the query gets stuck with just numbers(12).