Christian Spriegel created CASSANDRA-7401: ---------------------------------------------
Summary: Memtable.maybeUpdateLiveRatio goes into an endless loop when currentOperations is zero Key: CASSANDRA-7401 URL: https://issues.apache.org/jira/browse/CASSANDRA-7401 Project: Cassandra Issue Type: Bug Components: Core Reporter: Christian Spriegel Assignee: Christian Spriegel Hi, I was describing an error the other day on the mailing list, where the MemoryMeter would go into an endless loop. This happened multiple times last week, unfortunetaly I cannot reproduce it at the moment. The whole cassandra server got unresponsive and logged about 7000k messages per second into the log: {quote} ... INFO [MemoryMeter:1] 2014-06-14 19:24:09,488 Memtable.java (line 481) CFS(Keyspace='MDS', ColumnFamily='ResponsePortal') liveRatio is 64.0 (just-counted was 64.0). calculation took 0ms for 0 cells ... {quote} The cause for this seems to be Memtable.maybeUpdateLiveRatio(), which cannot handle currentOperations (and liveRatioComputedAt) to be zero. The loop will iterate endlessly: {code} ... if (operations < 2 * last) // does never break when zero: 0 < 0 is not true break; ... {code} One thing I cannot explain: How can the operationcount be zero when maybeUpdateLiveRatio() gets called? is it possible that addAndGet in resolve() increases by 0 in some cases? {code} currentOperations.addAndGet(cf.getColumnCount() + (cf.isMarkedForDelete() ? 1 : 0) + cf.deletionInfo().rangeCount()); // can this be zero? {code} Nevertheless, the attached patch fixes the endless loop. Feel free to reassign this ticket or create a followup ticket if currentOperations should not be zero. kind regards, Christian -- This message was sent by Atlassian JIRA (v6.2#6252)