Alexey Raga created KAFKA-3656: ---------------------------------- Summary: Avoid stressing system more when already under stress Key: KAFKA-3656 URL: https://issues.apache.org/jira/browse/KAFKA-3656 Project: Kafka Issue Type: Bug Reporter: Alexey Raga
I am working with Kafka Connect now and I am having error messages like that: {code} [2016-05-04 03:11:28,226] ERROR Failed to flush WorkerSourceTask{id=geo-connector-0}, timed out while waiting for producer to flush outstanding messages, 151860 left ([FAILED toString()]) (org.apache.kafka.connect.runtime.WorkerSourceTask:237) [2016-05-04 03:11:28,227] ERROR Failed to commit offsets for WorkerSourceTask{id=geo-connector-0} (org.apache.kafka.connect.runtime.SourceTaskOffsetCommitter:112) {code} I didn't figure out the reason why Connect would pull so many records into memory when it clearly can't produce that fast and I don't yet know why producing messages is slow. But the part of {{151860 left ([FAILED toString()]) }} is interesting and I looked at the code and found this: {code} if (timeoutMs <= 0) { log.error( "Failed to flush {}, timed out while waiting for producer to flush outstanding " + "messages, {} left ({})", this, outstandingMessages.size(), outstandingMessages); finishFailedFlush(); return false; } {code} So when the connector is under stress and, assuming {{151860}} messages, under a heavy memory pressure the code choses to take pretty much {{4 * 151860}} byte arrays and to convert it to a java string. This not only eats more memory and adds to GC, but is also useless for logging because the actual string, if it wouldn't fail, would look like: {code} (topic=lamington--geo-connector, partition=null, key=null, value=[B@62c66f62=ProducerRecord(topic=lamington--geo-connector, partition=null, key=null, value=[B@62c66f62, ProducerRecord(topic=lamington--geo-connector, partition=null, key=null, ..... {code} I think it is a bug and a string representation of the outstanding messages should be removed from the log. -- This message was sent by Atlassian JIRA (v6.3.4#6332)