Dear Jan, Thank you in advance for any time you invest in our issue. We were wondering if you had a chance to see our questions in response to your suggestions about enabling logging to further research our intermittent server crash issue? Best, Jeroen Andriessen On 27 Aug 2014, at 15:56 pm, Jeroen Andriessen wrote:

Hi Jan,

Thank you for answering, sorry for getting back to you so late with this answer. We are a little hesitant to post full unedited error_logs to the newsgroup, because of user information sensitivity.

Right now the problem hasn’t manifested itself for about a month. When you suggest enabling logging, I assume you are referring to the General Query Log? Or did you mean something else? As I understand it, enabling this log, with this great an interval between occurrences might mean a significant prolonged performance lag, due to the great amount of logging that wil occur. Do you think that is advisable? We wouldn’t want to run this logging for such an extended period of time.

Thank you for your advice,

Jeroen

On 30 Jul 2014, at 16:53 pm, Jan Lindström wrote:

...

Hi,

First thing is trying to identify which SQL-clause is causing this error and assertion. Could you provide us MariaDB configuration and full unedited error long from all the nodes. Furthermore, could you enable logging at least temporally adding log = log_file_name to your configuration and when/if problem repreoduces, provide the log files ?

R: Jan

On Wed, Jul 30, 2014 at 5:21 PM, Jeroen Andriessen wrote: Hi all,

We’re currently using a system with three clustered maria-db masters. We are experiencing occasional (once every three weeks or so) crashes of one of the server, namely our third server, which we use as a dedicated donor for the other two. The crashes point to a BF-BF X lock conflict in the same table. I was wondering how to proceed with identifying and localising the problem and counteracting it. We have already tried to rebuild the database in question from an earlier mysql dump, to no effect.

Any input is welcome, thanks.

——

BF-BF X lock conflict RECORD LOCKS space id 36361 page no 10 n bits 264 index `***REDACTED***` of table `***REDACTED***`.`***REDACTED***` trx id D860A49 lock_mode X locks rec but not gap 140724 6:10:53 [ERROR] mysqld got signal 6 ; This could be because you hit a bug. It is also possible that this binary or one of the libraries it was linked against is corrupt, improperly built, or misconfigured. This error can also be caused by malfunctioning hardware.

To report this bug, see http://kb.askmonty.org/en/reporting-bugs

We will try our best to scrape up some info that will hopefully help diagnose the problem, but since we have already crashed, something is definitely wrong and this may fail.

Server version: 5.5.38-MariaDB-wsrep-log key_buffer_size=134217728 read_buffer_size=131072 max_used_connections=7 max_threads=1002 thread_count=20 It is possible that mysqld could use up to key_buffer_size + (read_buffer_size + sort_buffer_size)*max_threads = 2329723 K bytes of memory Hope that's ok; if not, decrease some variables in the equation.

Thread pointer: 0x0x7f57b3412000 Attempting backtrace. You can use the following information to find out where mysqld died. If you see no messages after this, something went terribly wrong... stack_bottom = 0x7f5c1a16b940 thread_stack 0x48000 (my_addr_resolve failure: fork) /usr/sbin/mysqld(my_print_stacktrace+0x2b) [0xa95bab] /usr/sbin/mysqld(handle_fatal_signal+0x398) [0x6ebc58] /lib64/libpthread.so.0() [0x34e7e0f710] /lib64/libc.so.6(gsignal+0x35) [0x34e7632925] /lib64/libc.so.6(abort+0x175) [0x34e7634105] /usr/sbin/mysqld() [0x50e940] /usr/sbin/mysqld() [0x92c0ff] /usr/sbin/mysqld() [0x931799] /usr/sbin/mysqld() [0x932566] /usr/sbin/mysqld() [0x968a65] /usr/sbin/mysqld() [0x85fe3b] /usr/sbin/mysqld() [0x863ada] /usr/sbin/mysqld() [0x8642de] /usr/sbin/mysqld() [0x84e571] /usr/sbin/mysqld() [0x8337b2] /usr/sbin/mysqld(handler::ha_delete_row(unsigned char const*)+0xb0) [0x6f3640] /usr/sbin/mysqld(Delete_rows_log_event::do_exec_row(Relay_log_info const*)+0x10d) [0x7a41dd] /usr/sbin/mysqld(Rows_log_event::do_apply_event(Relay_log_info const*)+0x26a) [0x798e2a] /usr/sbin/mysqld(wsrep_apply_cb(void*, void const*, unsigned long, unsigned int, wsrep_trx_meta const*)+0x598) [0x69f988] /usr/lib64/galera/libgalera_smm.so(galera::TrxHandle::apply(void*, wsrep_cb_status (*)(void*, void const*, unsigned long, unsigned int, wsrep_trx_meta const*), wsrep_trx_meta const&) const+0xb1) [0x7f5c197462c1] /usr/lib64/galera/libgalera_smm.so(+0x1aaf95) [0x7f5c1977df95] /usr/lib64/galera/libgalera_smm.so(galera::ReplicatorSMM::apply_trx(void*, galera::TrxHandle*)+0x283) [0x7f5c1977ee03] /usr/lib64/galera/libgalera_smm.so(galera::ReplicatorSMM::process_trx(void*, galera::TrxHandle*)+0x45) [0x7f5c1977f6f5] /usr/lib64/galera/libgalera_smm.so(galera::GcsActionSource::dispatch(void*, gcs_action const&, bool&)+0x2c9) [0x7f5c1975c349] /usr/lib64/galera/libgalera_smm.so(galera::GcsActionSource::process(void*, bool&)+0x63) [0x7f5c1975c823] /usr/lib64/galera/libgalera_smm.so(galera::ReplicatorSMM::async_recv(void*)+0x93) [0x7f5c1977b3f3] /usr/lib64/galera/libgalera_smm.so(galera_recv+0x23) [0x7f5c19790743] /usr/sbin/mysqld() [0x6a037f] /usr/sbin/mysqld(start_wsrep_THD+0x365) [0x527415] /lib64/libpthread.so.0() [0x34e7e079d1] /lib64/libc.so.6(clone+0x6d) [0x34e76e8b5d]

Trying to get some variables. Some pointers may be invalid and cause the dump to abort. Query (0x0): is an invalid pointer Connection ID (thread ID): 17 Status: NOT_KILLED

Optimizer switch: index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_merge_sort_intersection=off,engine_condition_pushdown=off,index_condition_pushdown=on,derived_merge=on,derived_with_keys=on,firstmatch=on,loosescan=on,materialization=on,in_to_exists=on,semijoin=on,partial_match_rowid_merge=on,partial_match_table_scan=on,subquery_cache=on,mrr=off,mrr_cost_based=off,mrr_sort_keys=off,outer_join_with_cache=on,semijoin_with_cache=on,join_cache_incremental=on,join_cache_hashed=on,join_cache_bka=on,optimize_join_buffer_size=off,table_elimination=on,extended_keys=off

The manual page at http://dev.mysql.com/doc/mysql/en/crashing.html contains information that should help you find out what is causing the crash. 140724 06:10:53 mysqld_safe Number of processes running now: 0 140724 06:10:53 mysqld_safe WSREP: not restarting wsrep node automatically 140724 06:10:53 mysqld_safe mysqld from pid file /var/lib/mysql/***hostnameredacted***.pid ended _______________________________________________ Mailing list: https://launchpad.net/~maria-discuss Post to : maria-discuss@lists.launchpad.net Unsubscribe : https://launchpad.net/~maria-discuss More help : https://help.launchpad.net/ListHelp

-- --

Jan Lindström, Principal Engineer SkySQL - The MariaDB Company

skype: jan_p_lindstrom

www.skysql.com