Hi! It helps, but before I do more actions I want to give you some more info, and ask some questions:
*Related Info* 1. According to my yaml file (where do I see these parameters in the jmx? I couldn't find them): in_memory_compaction_limit_in_mb: 64 concurrent_compactors: 1, but it is commented out, so I guess it is the default value multithreaded_compaction: false compaction_throughput_mb_per_sec: 16 compaction_preheat_key_cache: true 2. According to cfstats there are the some CF with high Comacted row maximum sizes (1131752, 4866323 and 25109160). Others max sizes are < 1000000. Are these considered to be problematic, what can I do to solve that? 3. During compactions Cassandra is slower 4. Running Cassandra Version 1.0.8 *Questions* What should be the values of in_memory_compaction_limit_in_mb and concurrent_compactors and how do I change them? change yaml file and restart, or can it be done using jmx without restarting Cassandra? What do I do about the long rows? What value is considered too big. I appreciate your help! Thanks, *Tamar Fraenkel * Senior Software Engineer, TOK Media [image: Inline image 1] ta...@tok-media.com Tel: +972 2 6409736 Mob: +972 54 8356490 Fax: +972 2 5612956 On Tue, Aug 14, 2012 at 1:22 PM, aaron morton <aa...@thelastpickle.com>wrote: > There are a couple of steps you can take if compaction is causing GC. > > - if you have a lot of wide rows consider reducing > the in_memory_compaction_limit_in_mb yaml setting. This will slow down > compaction but will reduce the memory usage. > > - reduce concurrent_compactors > > Both of these may slow down compaction. Once you have GC under control > you may want to play with memory settings. > > Hope that helps. > ----------------- > Aaron Morton > Freelance Developer > @aaronmorton > http://www.thelastpickle.com > > On 14/08/2012, at 4:45 PM, Tamar Fraenkel <ta...@tok-media.com> wrote: > > Hi! > I have 3 nodes ring running on Amazon EC2. > About once a week I see in the logs compaction messages and around the > same time info messages about GC (see below) that I think means it is > taking too long and happening too often. > > Does it mean I have to reduce my cache size? > Thanks, > Tamar > > INFO [ScheduledTasks:1] 2012-08-13 12:50:57,593 GCInspector.java (line > 122) GC for ParNew: 242 ms for 1 collections, 1541590352 used; max is > 1937768448 > INFO [ScheduledTasks:1] 2012-08-13 12:51:27,740 GCInspector.java (line > 122) GC for ParNew: 291 ms for 1 collections, 1458227032 used; max is > 1937768448 > INFO [ScheduledTasks:1] 2012-08-13 12:51:29,741 GCInspector.java (line > 122) GC for ParNew: 261 ms for 1 collections, 1228861368 used; max is > 1937768448 > INFO [ScheduledTasks:1] 2012-08-13 12:51:30,833 GCInspector.java (line > 122) GC for ParNew: 319 ms for 1 collections, 1120131360 used; max is > 1937768448 > INFO [ScheduledTasks:1] 2012-08-13 12:51:32,863 GCInspector.java (line > 122) GC for ParNew: 241 ms for 1 collections, 983144216 used; max is > 1937768448 > INFO [ScheduledTasks:1] 2012-08-13 12:51:33,864 GCInspector.java (line > 122) GC for ParNew: 215 ms for 1 collections, 967702720 used; max is > 1937768448 > INFO [ScheduledTasks:1] 2012-08-13 12:51:34,964 GCInspector.java (line > 122) GC for ParNew: 248 ms for 1 collections, 973803344 used; max is > 1937768448 > INFO [ScheduledTasks:1] 2012-08-13 12:51:41,211 GCInspector.java (line > 122) GC for ParNew: 265 ms for 1 collections, 1071933560 used; max is > 1937768448 > INFO [ScheduledTasks:1] 2012-08-13 12:51:43,212 GCInspector.java (line > 122) GC for ParNew: 326 ms for 1 collections, 1217367792 used; max is > 1937768448 > INFO [ScheduledTasks:1] 2012-08-13 12:51:44,212 GCInspector.java (line > 122) GC for ParNew: 245 ms for 1 collections, 1203481536 used; max is > 1937768448 > INFO [ScheduledTasks:1] 2012-08-13 12:51:45,213 GCInspector.java (line > 122) GC for ParNew: 209 ms for 1 collections, 1208819416 used; max is > 1937768448 > INFO [ScheduledTasks:1] 2012-08-13 12:51:46,237 GCInspector.java (line > 122) GC for ParNew: 248 ms for 1 collections, 1338361648 used; max is > 1937768448 > > > *Tamar Fraenkel * > Senior Software Engineer, TOK Media > > <tokLogo.png> > > > ta...@tok-media.com > Tel: +972 2 6409736 > Mob: +972 54 8356490 > Fax: +972 2 5612956 > > > > >
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