Your analysis sounds correct to me. Can you open a ticket on
https://issues.apache.org/jira/browse/CASSANDRA ?
On Thu, Feb 17, 2011 at 10:17 AM, Ching-Cheng Chen
<cc...@evidentsoftware.com> wrote:
> We have observed the behavior that memtable_flush_after_mins setting not
> working occasionally. After some testing and code digging, we finally
> figured out what going on.
> The memtable_flush_after_mins won't work on certain condition with current
> implementation in Cassandra.
>
> In org.apache.cassandra.db.Table, the scheduled flush task is setup by the
> following code during construction.
>
> int minCheckMs = Integer.MAX_VALUE;
>
> for (ColumnFamilyStore cfs : columnFamilyStores.values())
> {
> minCheckMs = Math.min(minCheckMs, cfs.getMemtableFlushAfterMins() * 60 *
> 1000);
> }
> Runnable runnable = new Runnable()
> {
> public void run()
> {
> for (ColumnFamilyStore cfs : columnFamilyStores.values())
> {
> cfs.forceFlushIfExpired();
> }
> }
> };
> flushTask = StorageService.scheduledTasks.scheduleWithFixedDelay(runnable,
> minCheckMs, minCheckMs, TimeUnit.MILLISECONDS);
>
> Now for our application, we will create a keyspacewithout any columnfamily
> first. And only add needed columnfamily later depends on request.
> However, when keyspacegot created (without any columnfamily ), the above
> code will actually schedule a fixed delay flush check task with
> Integer.MAX_VALUE ms
> since there is no columnfamily yet.
> Later when you add columnfamily to this empty keyspace, the initCf() method
> in Table.java doesn't check whether the scheduled flush check task interval
> need
> to be updated or not. To fix this, we'd need to restart the Cassandra
> after columnfamily added into the keyspace.
> I would suggest that add additional logic in initCf() method to recreate a
> scheduled flush check task if needed.
> Regards,
> Chen
> www.evidentsoftware.com
--
Jonathan Ellis
Project Chair, Apache Cassandra
co-founder of Riptano, the source for professional Cassandra support
http://riptano.com
