Counting error in rdkafka_performance

[LionelCons]

I ran rdkafka_performance with:

$ rdkafka_performance -P -t performance-tests -c 60000000 -s 1000 -S 1 -a 0

It worked fine and at some point it has produced all the messages requested:

% 59895281 messages produced (59895281000 bytes), 59395313 delivered (offset 0, 0 failed) in 1032819ms: 57507 msgs/s and 57.51 MB/s, 1583935 produce failures, 499969 in queue, no compression
% 59943352 messages produced (59943352000 bytes), 59443359 delivered (offset 0, 0 failed) in 1033819ms: 57498 msgs/s and 57.50 MB/s, 1586516 produce failures, 499995 in queue, no compression
% 59999218 messages produced (59999218000 bytes), 59499222 delivered (offset 0, 0 failed) in 1034820ms: 57497 msgs/s and 57.50 MB/s, 1588434 produce failures, 499996 in queue, no compression
% 60000000 messages produced (60000000000 bytes), 59521253 delivered (offset 0, 0 failed) in 1035821ms: 57462 msgs/s and 57.46 MB/s, 1588447 produce failures, 478747 in queue, no compression
% 60000000 messages produced (60000000000 bytes), 59541214 delivered (offset 0, 0 failed) in 1036827ms: 57426 msgs/s and 57.43 MB/s, 1588447 produce failures, 458786 in queue, no compression
% 60000000 messages produced (60000000000 bytes), 59561058 delivered (offset 0, 0 failed) in 1037853ms: 57388 msgs/s and 57.39 MB/s, 1588447 produce failures, 438943 in queue, no compression

So far, so good.

However, near the end of the run, it reported:

% 60000000 messages produced (60000000000 bytes), 59960874 delivered (offset 0, 0 failed) in 1058937ms: 56623 msgs/s and 56.62 MB/s, 1588447 produce failures, 39128 in queue, no compression
% 60000000 messages produced (60000000000 bytes), 59979812 delivered (offset 0, 0 failed) in 1059938ms: 56587 msgs/s and 56.59 MB/s, 1588447 produce failures, 20198 in queue, no compression
% 60000000 messages produced (60000000000 bytes), 59997103 delivered (offset 0, 0 failed) in 1060944ms: 56550 msgs/s and 56.55 MB/s, 1588447 produce failures, 2901 in queue, no compression
% 1588447 backpressures for 60000000 produce calls: 2.647% backpressure rate
% 59999999 messages produced (59999999000 bytes), 60000000 delivered (offset 0, 0 failed) in 1061132ms: 56543 msgs/s and 56.54 MB/s, 1588447 produce failures, 0 in queue, no compression

As you can see, it went from "60000000 messages produced" down to "59999999 messages produced" but reported anyway "60000000 delivered"!

This is with librdkafka version 0.11.1 (0x000b01ff).

[edenhill]

There just happens to be an event enqueued for the application (which is accounted for in outq_len()):
https://github.com/edenhill/librdkafka/blob/master/examples/rdkafka_performance.c#L1340

That line should probably be removed.