Crash Log: yz_anti_entropy

Matthew Von-Maszewski matthewv at basho.com
Thu Jan 19 09:22:22 EST 2017


Damion,

I will explain what happened.  

ring_size = 8:  The default ring_size is 64.  It is based on the recommendation of five servers for a minimum cluster.  You stated you are using only one machine.  64 divided by 5 is 12.8 vnodes per server ... and ring size needs to be a power of 2.  So next smaller power of 2 from 12 is 8.

leveldb.limited_developer_mem = on:  leveldb allocates certain memory buffer size per vnode (ring_size).  This setting reduces the size of those buffers by 10x.  

The two settings squash the memory requirements to give you a better opportunity for happiness with both search and riak on a single server.

Matthew



> On Jan 19, 2017, at 9:15 AM, Junk, Damion A <junkda at purdue.edu> wrote:
> 
> Matthew -
> 
> That did it! 
> 
> Actually, I tried with both settings, and also with just the ring_size change. 
> 
> Setting ring_size to 8 got rid of crashing.  I'll have to do a bit more reading on this setting I suppose. I have a much more memory-constrained virtual machine running on my local desktop running with just the default install settings and no crashing. 
> 
> Thanks!
> 
> Damion
> 
>> On Jan 19, 2017, at 7:57 AM, Matthew Von-Maszewski <matthewv at basho.com <mailto:matthewv at basho.com>> wrote:
>> 
>> Damion,
>> 
>> Add the following settings within riak.conf:
>> 
>> leveldb.limited_developer_mem = on
>> ring_size = 8
>> 
>> Erase all data / vnodes and start over.
>> 
>> Matthew
>> 
>> 
>>> On Jan 19, 2017, at 8:51 AM, Junk, Damion A <junkda at purdue.edu <mailto:junkda at purdue.edu>> wrote:
>>> 
>>> Hi Magnus -
>>> 
>>> I've tried a wide range of parameters for leveldb.maximum_memory_percent ranging from 5 to 70. I also tried the leveldb.maximum_memory setting in bytes, ranging from 500MB to 4GB. I get the same results in the crash/console log no matter what the settings. But the log messages seem to indicate an issue with yokozuna, and not leveldb itself from what I can tell.
>>> 
>>> I set the max (-Xmx) to 2G for SOLR as well.
>>> 
>>> From the log messages, it looks like it's not actually the KV leveldb system that's crashing, but the yokozuna system. I'm not sure how to control or set memory here:
>>> 
>>>> {badmatch,{error,{db_open,"IO error: lock /var/lib/riak/yz_anti_entropy/639406966332270026714112114313373821099470487552/LOCK: Cannot allocate memory"}
>>> 
>>> This is a development node, running as a single (nojn-clustered) riak node. It has 14G memory, and at the time of trying changes with Riak, 9GB were free. 
>>> 
>>> 
>>> To Recap:
>>> 
>>> There are no keys/values in the database at all. 
>>> The only default settings I changed were:
>>> 
>>> storage_backend = leveldb
>>> search = on
>>> 
>>> and when that didn't work, I started changing:
>>> 
>>> search.solr.jvm_options = -d64 -Xms1g -Xmx2g -XX:+UseStringCache -XX:+UseCompressedOops
>>> leveldb.maximum_memory_percent = 5 .. 70 
>>> 
>>> and then when nothing seemed to change:
>>> 
>>> leveldb.maximum_memory =  1000000 ... 4000000000
>>> 
>>> 
>>> Thanks for any assistance!
>>> 
>>> 
>>> Damion
>>> 
>>> 
>>>> On Jan 19, 2017, at 3:33 AM, Magnus Kessler <mkessler at basho.com <mailto:mkessler at basho.com>> wrote:
>>>> 
>>>> Hi Damion,
>>>> 
>>>> Let me first state that AAE always uses leveldb, regardless of the storage backend chosen for Riak KV data. Could you please state how much physical memory your Riak nodes have, and what you have configured for "leveldb.maximum_memory.percent" in "riak.conf"? Have you changed the settings for "search.solr.jvm_options", in particular the memory allocated to Solr?
>>>> 
>>>> As a general rule, leveldb should have at least 350MB of memory available per partition, and performance has been shown to increase with up to 2GB (2.5 GB when also using Search and AAE) per partition. Please check that you have enough memory available in your system.
>>>> 
>>>> Kind Regards,
>>>> 
>>>> Magnus
>>>>  
>>>> -- 
>>>> Magnus Kessler
>>>> Client Services Engineer
>>>> Basho Technologies Limited
>>>> 
>>>> Registered Office - 8 Lincoln’s Inn Fields London WC2A 3BP Reg 07970431
>>> 
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>> 
> 

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