Leveldb segfault during Riak startup

Antti Kuusela antti.kuusela at firstbeat.fi
Thu Dec 31 06:06:11 EST 2015


Hi Luke,

We erased the btrfs file system, replaced it with xfs on lvm with 
thinly-provisioned volumes and continued testing with a new database 
from scratch. The same problem continues, though. From /var/log/messages:

Dec 31 03:35:31 storage5 riak[66419]: Starting up
Dec 31 03:35:45 storage5 kernel: traps: beam.smp[66731] general 
protection ip:7f02280b3f16 sp:7f0197ad8dd0 error:0 in 
eleveldb.so[7f0228066000+93000]
Dec 31 03:35:46 storage5 run_erl[66417]: Erlang closed the connection.



18.12.2015, 16:45, Luke Bakken kirjoitti:
> Hi Antti,
>
> Riak is not tested on btrfs and the file system is not officially
> supported. We recommend ext4 or xfs for Linux. ZFS is an option on
> Solaris derivatives and FreeBSD.
>
> --
> Luke Bakken
> Engineer
> lbakken at basho.com
>
>
> On Fri, Dec 18, 2015 at 6:14 AM, Antti Kuusela
> <antti.kuusela at firstbeat.fi> wrote:
>> Hi,
>>
>> I have been testing Riak and Riak CS as a possible solution for our future
>> storage needs. I have a five server cluster running Centos 7. Riak version
>> is 2.1.3 (first installed as 2.1.1, updated twice via Basho repo) and Riak
>> CS version is 2.1.0. The servers each have 64GB RAM and six 4TB disks in
>> raid 6 using btrfs.
>>
>> I have been pushing random data into Riak-CS via s3cmd to see how the system
>> behaves. Smallest objects have been 2000 bytes, largest 100MB. I have also
>> been making btrfs snapshots of the entire platform data dir nightly for
>> backup purposes. Stop Riak CS, wait 10 seconds, stop Riak, wait 10, make
>> snapshot, start Riak, wait 180 seconds, start Riak CS. This is performed on
>> each of the servers in turn with a five minute wait in between. I have added
>> the waits to try spread the startup load and allow the system time to get
>> things running. New data is constantly pushed to the S3 API but restarting
>> the nodes in rotation causes by far the highest stress on the system.
>>
>> I have encountered one problem in particular. Quite often one of the Riak
>> nodes starts up but after a couple of minutes it just drops, all processes
>> exited except for epmd.
>>
>> Following is from /var/log/riak/console, most of the lines skipped for sake
>> of brevity. Normal startup stuff, as far as I can see:
>>
>> 2015-12-16 00:26:04.446 [info] <0.7.0> Application lager started on node
>> 'riak at 192.168.50.32'
>> ...
>> 2015-12-16 00:26:04.490 [info] <0.72.0> alarm_handler:
>> {set,{system_memory_high_watermark,[]}}
>> ...
>> 2015-12-16 00:26:04.781 [info]
>> <0.206.0>@riak_core_capability:process_capability_changes:555 New
>> capability: {riak_core,vnode_routing} = proxy
>> ...
>> 2015-12-16 00:26:04.869 [info] <0.7.0> Application riak_core started on node
>> 'riak at 192.168.50.32'
>> ...
>> 2015-12-16 00:26:04.969 [info] <0.407.0>@riak_kv_env:doc_env:46 Environment
>> and OS variables:
>> 2015-12-16 00:26:05.124 [warning] <0.6.0> lager_error_logger_h dropped 9
>> messages in the last second that exceeded the limit of 100 messages/sec
>> 2015-12-16 00:26:05.124 [info] <0.407.0> riak_kv_env: Open file limit: 65536
>> 2015-12-16 00:26:05.124 [warning] <0.407.0> riak_kv_env: Cores are disabled,
>> this may hinder debugging
>> 2015-12-16 00:26:05.124 [info] <0.407.0> riak_kv_env: Erlang process limit:
>> 262144
>> 2015-12-16 00:26:05.125 [info] <0.407.0> riak_kv_env: Erlang ports limit:
>> 65536
>> 2015-12-16 00:26:05.125 [info] <0.407.0> riak_kv_env: ETS table count limit:
>> 256000
>> 2015-12-16 00:26:05.125 [info] <0.407.0> riak_kv_env: Thread pool size: 64
>> 2015-12-16 00:26:05.125 [info] <0.407.0> riak_kv_env: Generations before
>> full sweep: 0
>> 2015-12-16 00:26:05.125 [info] <0.407.0> riak_kv_env: Schedulers: 12 for 12
>> cores
>> 2015-12-16 00:26:05.125 [info] <0.407.0> riak_kv_env: sysctl vm.swappiness
>> is 0 greater than or equal to 0)
>> 2015-12-16 00:26:05.125 [info] <0.407.0> riak_kv_env: sysctl
>> net.core.wmem_default is 8388608 lesser than or equal to 8388608)
>> ...
>> 2015-12-16 00:26:05.139 [info] <0.478.0>@riak_core:wait_for_service:504
>> Waiting for service riak_kv to start (0 seconds)
>> 2015-12-16 00:26:05.158 [info]
>> <0.495.0>@riak_kv_entropy_manager:set_aae_throttle_limits:790 Setting AAE
>> throttle limits: [{-1,0},{200,10},{500,50},{750,250},{900,1000},{1100,5000}]
>> ...
>> 2015-12-16 00:26:30.160 [info]
>> <0.495.0>@riak_kv_entropy_manager:perhaps_log_throttle_change:853 Changing
>> AAE throttle from undefined -> 5000 msec/key, based on maximum vnode mailbox
>> size {unknown_mailbox_sizes,node_list,['riak at 192.168.50.32']} from
>> ['riak at 192.168.50.32']
>> 2015-12-16 00:27:12.053 [info] <0.478.0>@riak_core:wait_for_service:504
>> Waiting for service riak_kv to start (60 seconds)
>> 2015-12-16 00:28:25.057 [info] <0.478.0>@riak_core:wait_for_service:504
>> Waiting for service riak_kv to start (120 seconds)
>>
>> And then nothing
>>
>>  From /var/log/messages:
>>
>> Dec 16 00:26:02 storage2 su: (to riak) root on none
>> Dec 16 00:26:04 storage2 riak[48174]: Starting up
>> Dec 16 00:28:59 storage2 kernel: traps: beam.smp[48492] general protection
>> ip:7fcaf9402f16 sp:7fca6affcdd0 error:0 in eleveldb.so[7fcaf93b5000+93000]
>> Dec 16 00:28:59 storage2 run_erl[48172]: Erlang closed the connection.
>>
>> On another node at a different time /var/log/riak/console.log had similar
>> messages, and also some warnings about invalid hint files, such as:
>>
>> 2015-12-13 00:15:41.232 [warning] <0.815.0> Hintfile
>> '/data/riak/bitcask/570899077082383952423314387779798054553098649600/56.bitcask.hint'
>> invalid
>>
>> In this latter example riak was started with "systemctl start riak" rather
>> than "riak start". From /var/log/messages:
>>
>> Dec 13 00:15:29 storage1 riak: Starting riak: [  OK  ]
>> Dec 13 00:15:29 storage1 systemd: Started SYSV: Riak is a distributed data
>> store.
>> Dec 13 00:15:56 storage1 kernel: beam.smp[131820]: segfault at 160 ip
>> 00007f24c0902ce6 sp 00007f24337fddd0 error 4 in
>> eleveldb.so[7f24c08b5000+93000]
>> Dec 13 00:15:56 storage1 run_erl[131501]: Erlang closed the connection.
>>
>> Of reported Riak bugs, this is similar to
>> https://github.com/basho/riak/issues/790 . However, the poster of that issue
>> reported that his problem was fixed by repairing leveldb partitions. I
>> looked at this following
>> http://docs.basho.com/riak/latest/ops/running/recovery/repairing-leveldb/
>> but didn't find any errors.
>>
>> Incidentally, I started having problems with btrfs as well. On one node
>> btrfs caused a kernel crash and on another kernel killed beam.smp process
>> after it stopped responding for over 120 seconds while syncing to btrfs. The
>> kernel in Centos 7 probably isn't best suited for working with btrfs.
>> Advertised version is 3.10.0.
>>
>> So, my question is what is your take on this? Is this a bug in the leveldb
>> library? The same one already reported? What log data would help debug or
>> reproduce it? Or is there potentially some problem with my setup? Or could
>> this be caused by a bug in btrfs? What is your take on using Riak with
>> btrfs?
>>
>> --
>> Antti Kuusela, M.Sc
>> Senior Software Developer
>> Firstbeat Technologies Ltd.
>>
>>
>> _______________________________________________
>> riak-users mailing list
>> riak-users at lists.basho.com
>> http://lists.basho.com/mailman/listinfo/riak-users_lists.basho.com
> .
>


-- 
Antti Kuusela, M.Sc
Senior Software Developer
Firstbeat Technologies Ltd.





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