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  1. MariaDB Server
  2. MDEV-16527

Spider crash in background thread




      During testing (only ran a simple PK query on a big spider table partitioned on 4 datanodes and some monitoring queries, like: show table status from `db` like 't1') the server crashed in a spider backend thread

      Using host libthread_db library "/lib64/libthread_db.so.1".
      Core was generated by `/usr/local/mysql/bin/mysqld --defaults-file=/etc/my.cnf --user=mysql --core-fil'.
      Program terminated with signal 11, Segmentation fault.
      #0  0x00007fbe9a044a01 in pthread_kill () from /lib64/libpthread.so.0
      Missing separate debuginfos, use: debuginfo-install glibc-2.17-222.el7.x86_64 libaio-0.3.109-13.el7.x86_64 libgcc-4.8.5-28.el7.x86_64 libstdc++-4.8.5-28.el7.x86_64 nss-softokn-freebl-3.34.0-2.el7.x86_64 sssd-client-1.16.0-19.el7.x86_64 xz-libs-5.2.2-1.el7.x86_64
      (gdb) bt
      #0  0x00007fbe9a044a01 in pthread_kill () from /lib64/libpthread.so.0
      #1  0x00007fbe9abfbfc2 in handle_fatal_signal (sig=11)
          at /MariaDB/server/sql/signal_handler.cc:305
      #2  <signal handler called>
      #3  movelink (newlink=1, next_link=4294967295, find=0, array=0x7fbe9c55b068)
          at /MariaDB/server/mysys/hash.c:337
      #4  my_hash_insert (info=0x7fbe9c553710, record=0x7fbdc4011598 "\001")
          at /MariaDB/server/mysys/hash.c:517
      #5  0x00007fbe21727399 in spider_get_conn (share=share@entry=0x7fbcd407ba28, link_idx=<optimized out>, 
          link_idx@entry=0, conn_key=<optimized out>, trx=0x7fbe9c553648, spider=spider@entry=0x7fbcd4085b40, 
          another=another@entry=false, thd_chg=thd_chg@entry=false, conn_kind=conn_kind@entry=1, 
          error_num=error_num@entry=0x7fbde77fde60) at /MariaDB/server/storage/spider/spd_conn.cc:1126
      #6  0x00007fbe2173c5c8 in spider_table_bg_crd_action (arg=arg@entry=0x7fbe9c54fb78)
          at /MariaDB/server/storage/spider/spd_table.cc:10169
      #7  0x00007fbe9b12360d in pfs_spawn_thread (arg=0x7fbe9c550ae8)
          at /MariaDB/server/storage/perfschema/pfs.cc:1862
      #8  0x00007fbe9a03fe25 in start_thread () from /lib64/libpthread.so.0
      #9  0x00007fbe98efcbad in clone () from /lib64/libc.so.6
      (gdb) up
      #1  0x00007fbe9abfbfc2 in handle_fatal_signal (sig=11)
          at /MariaDB/server/sql/signal_handler.cc:305
      warning: Source file is more recent than executable.
      305	    my_write_core(sig);
      (gdb) up
      #2  <signal handler called>
      (gdb) up
      #3  movelink (newlink=1, next_link=4294967295, find=0, array=0x7fbe9c55b068)
          at /MariaDB/server/mysys/hash.c:337
      warning: Source file is more recent than executable.
      337	  while ((next_link=old_link->next) != find);
      (gdb) p old_link
      $1 = (HASH_LINK *) 0x7fce9c55b058
      (gdb) p find
      $2 = 0
      (gdb) p next_link
      $3 = 4294967295
      (gdb) p old_link->next
      Cannot access memory at address 0x7fce9c55b058

      In the mysqld.log there are also other hints:

      20180619 18:16:08 [SEND SPIDER SQL] from 2 to [spider-datanode3.example.com] 6120658:  sql: show table status from `db` like 't3'
      180619 18:16:08 20180619 18:16:08 [SEND SPIDER SQL] from 9 to [spider-datanode2.example.com] 5459221:  sql: show table status from `db` like 't3'
      [ERROR] mysqld got signal 11 ;
      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 https://mariadb.com/kb/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: 10.3.7-MariaDB-log
      20180619 18:16:08 [SEND SPIDER SQL] from 7 to [spider-datanode1.example.com] 3978791:  sql: show table status from `db` like 't3'
      It is possible that mysqld could use up to 
      key_buffer_size + (read_buffer_size + sort_buffer_size)*max_threads = 4311648 K  bytes of memory
      Hope that's ok; if not, decrease some variables in the equation.
      Thread pointer: 0x7fbdc40009a8
      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 = 0x7fbde77fdd90 thread_stack 0x49000
      20180619 18:16:08 [SEND SPIDER SQL] from 7 to [spider-datanode4.example.com] 23775456:  sql: show table status from `db` like 't3'
      spider/spd_conn.cc:1126(spider_get_conn(st_spider_share*, int, char*, st_spider_transaction*, ha_spider*, bool, bool, unsigned int, int*))[0x7fbe21727399]
      Trying to get some variables.
      Some pointers may be invalid and cause the dump to abort.
      Query (0x0): 
      Connection ID (thread ID): 18
      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=on,exists_to_in=on,orderby_uses_equalities=on,condition_pushdown_for_derived=on,split_materialized=on
      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.
      Writing a core file at /mysql/db/data/

      (Also notice the minor bugs in the crashing message: pointing to dev.mysql.com seems wrong when the MariaDB server crashes. 'Writing a core file at /mysql/db/data' is wrong, the config is different!)




            Kentoku Kentoku Shiba
            mattiasjonsson Mattias Jonsson
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