[KAFKA-5641] Metadata request should always be allowed to send no regardless of value for max.in.flight.requests.per.connection

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Not A Problem
• Affects Version/s: 0.11.0.0
• Component/s: network, producer
• Assignee: Unassigned
• Reporter: huxihx
• Created: 26/Jul/17 05:42
• Updated: 02/Aug/17 08:54
• Resolved: 02/Aug/17 08:54

Description

Metadata request might not be able to be sent when `max.in.flight.requests.per.connection` is set to 1 and there is already an inflight request in the same node's queue, as show below:

NetworkClient.java

private long maybeUpdate(long now, Node node) {
            String nodeConnectionId = node.idString();
            if (canSendRequest(nodeConnectionId)) {
            ......
            }

However, setting `max.in.flight.requests.per.connection` to 1 actually means no out-of-order for the produced records, Metadata requests should have no related with this config. We don't have to check the inflight request's queue size when sending Metadata request.

ijuma Does it make any sense? If yes, I will work on it.