Perhaps it was just some mismatch between the expectation (pooled, long-running connections) and reality. (many, many short-lived connections) I think another

Perhaps it was just some mismatch between the expectation (pooled, long-running connections) and reality. (many, many short-lived connections) I think another takeaway from this is any time you need to adjust the ulimit, take a step back and ask "Does this make sense? Is my use case exceptional enough that it won't perform within the default limits set by my OS?"