Thank you both for your answer!
After several tests with different parameters we came to the
conclusion that it must be a bug.
It looks very similar to: https://issues.apache.org/jira/browse/CASSANDRA-1014
For both CFs we reduced thresholds:
- memtable_flush_after_mins = 60 (both CFs are used permanently,
therefore other thresholds should trigger first)
- memtable_throughput_in_mb = 40
- memtable_operations_in_millions = 0.3
- keys_cached = 0
- rows_cached = 0
- in_memory_compaction_limit_in_mb = 64
First we disabled caching, later we disabled compacting and after that we set
But our problem still appears:
During inserting files with Lucandra memory usage is slowly growing
until OOM crash after about 50 min.
@Peter: In our latest test we stopped writing suddenly but cassandra
didn\'t relax and remains even after minutes on ~90% heap usage.
With our heap calculation we should need:
64 MB * 2 * 3 + 1 GB = 1,4 GB
All recent tests we run with 3 GB. I think that should be ok for a
Also consistency level is one.
But Aaron is right, Lucandra produces even more than 200 inserts/s.
My 200 documents per second are about 200 operations (writecount) on
first CF and about 3000 on second CF.
But even with about 120 documents/s cassandra crashes.
Disk I/O monitored with Windows performance admin tools is on both
discs moderate (commitlog is on seperate harddisc).
If it's really a bug, in my opinion it's very critical.
Aaron Morton <firstname.lastname@example.org> wrote:
> I remember you have 2 CF's but what are the settings for:
> - memtable_flush_after_mins
> - memtable_throughput_in_mb
> - memtable_operations_in_millions
> - keys_cached
> - rows_cached
> - in_memory_compaction_limit_in_mb
> Can you do the JVM Heap Calculation here and see what it says
> What Consistency Level are you writing at? (Checking it's not Zero)
> When you talk about 200 inserts per second is that storing 200
> documents through lucandra or 200 request to cassandra. If it's the
> first option I would assume that would generate a lot more actual
> requests into cassandra. Open up jconsole and take a look at the
> WriteCount settings for the
> CF's http://wiki.apache.org/cassandra/MemtableThresholds
> You could also try setting the compaction thresholds to 0 to disable
> compaction while you are pushing this data in. Then use node tool to
> compact and turn the settings back to normal. See cassandra.yam for
> more info.
> I would have thought you could get the writes through with the setup
> you've described so far (even though a single 32bit node is unusual).
> The best advice is to turn all the settings down (e.g. caches off,
> mtable flush 64MB, compaction disabled) and if it still fails try:
> - checking your IO stats, not sure on windows but JConsole has some IO
> stats. If your IO cannot keep up then your server is not fast enough
> for your client load.
> - reducing the client load
> Hope that helps.
> On 04 Dec, 2010,at 05:23 AM, Max <email@example.com> wrote:
> we increased heap space to 3 GB (with JRocket VM under 32-bit Win with
> 4 GB RAM)
> but under "heavy" inserts Cassandra is still crashing with OutOfMemory
> error after a GC storm
> It sounds very similar to
> In our insert-tests the average heap usage is slowly growing up to the
> 3 GB border (jconsole monitor over 50 min
) and the CompactionManger queue is
> also constantly growing up to about 50 jobs pending
> We tried to decrease CF memtable threshold but after about half a
> million inserts it's over.
> - Cassandra 0.7.0 beta 3
> - Single Node
> - about 200 inserts/s ~500byte - 1 kb
> Is there no other possibility instead of slowing down inserts/s ?
> What could be an indicator to see if a node works stable with this
> amount of inserts?
> Thank you for your answer,
> Aaron Morton <firstname.lastname@example.org>:
>> Sounds like you need to increase the Heap size and/or reduce the
>> memtable_throughput_in_mb and/or turn off the internal caches.
>> Normally the binary memtable thresholds only apply to bulk load
>> operations and it's the per CF memtable_* settings you want to
>> change. I'm not familiar with lucandra though.
>> See the section on JVM Heap Size here
>> Bottom line is you will need more JVM heap memory.
>> Hope that helps.
>> On 29 Nov, 2010,at 10:28 PM, email@example.com wrote:
>> Hi community,
>> during my tests i had several OOM crashes.
>> Getting some hints to find out the problem would be nice.
>> First cassandra crashes after about 45 min insert test script.
>> During the following tests time to OOM was shorter until it started to crash
>> even in "idle" mode.
>> Here the facts:
>> - cassandra 0.7 beta 3
>> - using lucandra to index about 3 million files ~1kb data
>> - inserting with one client to one cassandra node with about 200 files/s
>> - cassandra data files for this keyspace grow up to about 20 GB
>> - the keyspace only contains the two lucandra specific CFs
>> - cassandra single node on windows 32bit, Xeon 2,5 Ghz, 4GB RAM
>> - java jre 1.6.0_22
>> - heap space first 1GB, later increased to 1,3 GB
>> default + reduced "binary_memtable_throughput_in_mb" to 128
>> default + reduced
>> min_compaction_threshold: 4
>> max_compaction_threshold: 8
>> I think the problem appears always during compaction,
>> and perhaps it is a result of large rows (some about 170mb).
>> Are there more options we could use to work with few memory?
>> Is it a problem of compaction?
>> And how to avoid?
>> Slower inserts? More memory?
>> Even fewer memtable_throuput or in_memory_compaction_limit?
>> Continuous manual major comapction?
>> I've read
>> - row_size should be fixed since 0.7 and 200mb is still far away from 2gb
>> - only key cache is used a little bit 3600/20000
>> - after a lot of writes cassandra crashes even in idle mode
>> - memtablesize was reduced and there are only 2 CFs
>> Several heapdumps in MAT show 60-99% heapusage of compaction thread.