Merge jobs are currently broken due to IMPALA-5733 <https://issues.apache.org/jira/browse/IMPALA-5733> - where Kudu tablet servers are getting killed because of memory pressure on the machine. Please refrain from submitting new merge jobs until someone gives the all clear.
We don't currently have an ETA for a fix. Looks like this only started happening recently, so hopefully we'll be able to identify the culprit in short order. Thanks for your patience! Henry