I just noticed this thread. Does this mean that (assuming the same setup of an empty keyspace and CFs added later) if I have a CF that I write to for some time, but not enough to hit the flush limits, it will never get flushed until the server is restarted? I believe this is causing commit logs to not be deleted, which is taking up a ton of disk space (in addition to a bunch of small memtables being stuck in memory).
-Jeffrey From: Ching-Cheng Chen [mailto:cc...@evidentsoftware.com] Sent: Thursday, February 17, 2011 8:52 AM To: user@cassandra.apache.org Cc: Jonathan Ellis Subject: Re: memtable_flush_after_mins setting not working https://issues.apache.org/jira/browse/CASSANDRA-2183 Regards, Chen www.evidentsoftware.com<http://www.evidentsoftware.com> On Thu, Feb 17, 2011 at 11:47 AM, Ching-Cheng Chen <cc...@evidentsoftware.com<mailto:cc...@evidentsoftware.com>> wrote: Certainly, I'll open a ticket to track this issue. Regards, Chen www.evidentsoftware.com<http://www.evidentsoftware.com> On Thu, Feb 17, 2011 at 11:42 AM, Jonathan Ellis <jbel...@gmail.com<mailto:jbel...@gmail.com>> wrote: 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<mailto: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<http://www.evidentsoftware.com> -- Jonathan Ellis Project Chair, Apache Cassandra co-founder of Riptano, the source for professional Cassandra support http://riptano.com -- www.evidentsoftware.com<http://www.evidentsoftware.com>
