Re: MemtablePostFlush pending

2017-08-15 Thread Erick Ramirez 
Check what you have set for memtable_cleanup_threshold and if it's set too
low which means more flushing triggered. Cheers!

On Sat, Aug 12, 2017 at 5:05 AM, ZAIDI, ASAD A  wrote:

> Hello Folks,
>
>
>
> I’m using Cassandra 2.2 on 14 node cluster.
>
>
>
> Now a days, I’m observing memtablepostflush pending number going high ,
> this happens intermittently. I’m looking if  Is there way to ‘tune’
> memtablepostflush stage?
>
>
>
> Thanks/ASad
>
>
>

Re: MemtablePostFlush pending

2017-08-13 Thread Akhil Mehra 
HI Asad,

The post flush task frees up allocated commit log segments.

Apart for commit log segment allocation the post flush task "synchronises 
custom secondary indexes and provides ordering guarantees for futures on 
switchMemtable/flush
etc, which expect to be able to wait until the flush (and all prior flushes) 
requested have completed."

The post flush executor is a single threaded thread pool that cannot be tuned 
(https://github.com/apache/cassandra/blob/8b3a60b9a7dbefeecc06bace617279612ec7092d/src/java/org/apache/cassandra/db/ColumnFamilyStore.java#L160-L167
 
<https://github.com/apache/cassandra/blob/8b3a60b9a7dbefeecc06bace617279612ec7092d/src/java/org/apache/cassandra/db/ColumnFamilyStore.java#L160-L167>)

Are you using secondary indexes? I there a high write throughput which is 
resulting in frequent meltable flushes?

Regards,
Akhil





> On 12/08/2017, at 7:05 AM, ZAIDI, ASAD A  wrote:
> 
> Hello Folks,
>  
> I’m using Cassandra 2.2 on 14 node cluster.
>  
> Now a days, I’m observing memtablepostflush pending number going high , this 
> happens intermittently. I’m looking if  Is there way to ‘tune’ 
> memtablepostflush stage?
>  
> Thanks/ASad

MemtablePostFlush pending

2017-08-11 Thread ZAIDI, ASAD A 
Hello Folks,

I’m using Cassandra 2.2 on 14 node cluster.

Now a days, I’m observing memtablepostflush pending number going high , this 
happens intermittently. I’m looking if  Is there way to ‘tune’ 
memtablepostflush stage?

Thanks/ASad

MemtablePostFlush pending

2017-06-01 Thread ZAIDI, ASAD A 
Hello Folks,

I'm adding another node on my 14 node open source apache cassandra 2.2.8 
cluster.  New node is taking long time to join the cluster.
I see there are bunch of pending [memtablepostflush] threads. I did increase 
memtable_flush_writers from 8 to 24 , though it is not helping with situation.

Can you guys please share your experience or advise me what else I can look so 
to  remediate the situation.


nodetool tpstats
Pool NameActive   Pending  Completed   Blocked  All 
time blocked
MutationStage 0 08543301 0  
   0
ReadStage 0 0  0 0  
   0
RequestResponseStage  0 0  0 0  
   0
ReadRepairStage   0 0  0 0  
   0
CounterMutationStage  0 0  0 0  
   0
GossipStage   0 0  0 0  
   0
MigrationStage0 0  0 0  
   0
MemtablePostFlush 1   388 15 0  
   0
ValidationExecutor0 0  0 0  
   0
Sampler   0 0  0 0  
   0
MiscStage 0 0  0 0  
   0
MemtableFlushWriter   3 3133 0  
   0
InternalResponseStage 0 0  0 0  
   0
CompactionExecutor0 0 18 0  
   0
MemtableReclaimMemory 0 0133 0  
   0
AntiEntropyStage  0 0  0 0  
   0
CacheCleanupExecutor  0 0  0 0  
   0

Message type   Dropped
READ 0
RANGE_SLICE  0
_TRACE   0
MUTATION 0
COUNTER_MUTATION 0
REQUEST_RESPONSE 0
PAGED_RANGE  0
READ_REPAIR  0