The behavior was seen with row caching off. I now have row caching on. key cache hit rate is 0.75-0.8 row cache hit rate is 0 (row cache capacity=1, RowsCached="100%")
looks like I should try another format for RowsCached, like "0.8" or "90%" or something. On Thu, Jun 17, 2010 at 1:47 PM, aaron morton <aa...@thelastpickle.com> wrote: > Do you have Row Caching enabled ? You can check in the JMX console to see if > you're hitting the cache. > > Try turning on DEBUG level logging and look at the log on a machine you > connect to do the read. > > > Aaron > > On 18 Jun 2010, at 05:31, AJ Slater wrote: > >> Total data size in the entire cluster is about twenty 12k images. With >> no other load on the system. I just ask for one column and I get these >> timeouts. Performing multiple gets on the columns leads to multiple >> timeouts for a period of a few seconds or minutes and then the >> situation magically resolves itself and response times are down to >> single digit milliseconds for a column get. >> >> On Thu, Jun 17, 2010 at 10:24 AM, AJ Slater <a...@zuno.com> wrote: >>> Cassandra 0.6.2 from the apache debian source. >>> Ubunutu Jaunty. Sun Java6 jvm. >>> >>> All nodes in separate racks at 365 main. >>> >>> On Thu, Jun 17, 2010 at 10:12 AM, AJ Slater <a...@zuno.com> wrote: >>>> I'm seing 10s timeouts on reads few times a day. Its hard to reproduce >>>> consistently but seems to happen most often after its been a long time >>>> between reads. After presenting itself for a couple minutes the >>>> problem then goes away. >>>> >>>> I've got a three node cluster with replication factor 2, reading at >>>> consistency level ONE. The columns being read are around 12k each. The >>>> nodes are 8GB multicore boxes with the JVM limits between 4GB and 6GB. >>>> >>>> Here's an application log from early this morning when a developer in >>>> Belgrade accessed the system: >>>> >>>> Jun 17 03:54:17 lpc03 pinhole[5736]: MainThread:pinhole.py:61 | >>>> Requested image_id: 5827067133c3d670071c17d9144f0b49 >>>> Jun 17 03:54:27 lpc03 pinhole[5736]: MainThread:pinhole.py:76 | >>>> TimedOutException for Image 5827067133c3d670071c17d9144f0b49 >>>> Jun 17 03:54:27 lpc03 pinhole[5736]: MainThread:zlog.py:105 | Image >>>> Get took 10005.388975 ms >>>> Jun 17 03:54:27 lpc03 pinhole[5736]: MainThread:pinhole.py:61 | >>>> Requested image_id: af8caf3b76ce97d13812ddf795104a5c >>>> Jun 17 03:54:27 lpc03 pinhole[5736]: MainThread:zlog.py:105 | Image >>>> Get took 3.658056 ms >>>> Jun 17 03:54:27 lpc03 pinhole[5736]: MainThread:zlog.py:105 | Image >>>> Transform took 0.978947 ms >>>> >>>> That's a Timeout and then a successful get of another column. >>>> >>>> Here's the cassandra log for 10.33.2.70: >>>> >>>> DEBUG 03:54:17,070 get_slice >>>> DEBUG 03:54:17,071 weakreadremote reading >>>> SliceFromReadCommand(table='jolitics.com', >>>> key='5827067133c3d670071c17d9144f0b49', >>>> column_parent='QueryPath(columnFamilyName='Images', >>>> superColumnName='null', columnName='null')', start='', finish=' >>>> ', reversed=false, count=100) >>>> DEBUG 03:54:17,071 weakreadremote reading >>>> SliceFromReadCommand(table='jolitics.com', >>>> key='5827067133c3d670071c17d9144f0b49', >>>> column_parent='QueryPath(columnFamilyName='Images', >>>> superColumnName='null', columnName='null')', start='', finish=' >>>> ', reversed=false, count=100) from 45138@/10.33.3.10 >>>> DEBUG 03:54:27,077 get_slice >>>> DEBUG 03:54:27,078 weakreadlocal reading >>>> SliceFromReadCommand(table='jolitics.com', >>>> key='af8caf3b76ce97d13812ddf795104a5c', >>>> column_parent='QueryPath(columnFamilyName='Images', >>>> superColumnName='null', columnName='null')', start='', finish='' >>>> , reversed=false, count=100) >>>> DEBUG 03:54:27,079 collecting body:false:1...@1275951327610885 >>>> DEBUG 03:54:27,080 collecting body:false:1...@1275951327610885 >>>> DEBUG 03:54:27,080 Reading consistency digest for >>>> af8caf3b76ce97d13812ddf795104a >>>> 5c from 45...@[/10.33.2.70, /10.33.3.10] >>>> DEBUG 03:54:50,779 Disseminating load info ... >>>> >>>> It looks like it asks for key='5827067133c3d670071c17d9144f0b49' from >>>> the local host and also queries 10.33.3.10 for the first one and then >>>> for 'af8caf3b76ce97d13812ddf795104a5c' it only queries the local host >>>> and then returns appropriately. >>>> >>>> Here's the log for 10.33.3.10 around that time: >>>> >>>> DEBUG 03:54:19,645 Disseminating load info ... >>>> DEBUG 03:55:19,645 Disseminating load info ... >>>> DEBUG 03:56:19,646 Disseminating load info ... >>>> DEBUG 03:57:19,645 Disseminating load info ... >>>> DEBUG 03:58:19,645 Disseminating load info ... >>>> DEBUG 03:59:19,646 Disseminating load info ... >>>> DEBUG 04:00:18,635 GC for ParNew: 4 ms, 21443128 reclaimed leaving >>>> 55875144 used; max is 6580535296 >>>> >>>> No record of communication from 10.33.2.70. >>>> >>>> Does this ring any bells for anyone? I can of course attach >>>> storage-conf's for all nodes if that sounds useful and I'll be on >>>> #cassandra as ajslater. >>>> >>>> Much thanks for taking a look and any suggestions. We fear we'll have >>>> to abandon Cassandra if this bug cannot be resolved. >>>> >>>> AJ >>>> >>> > >
