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  1. WiredTiger
  2. WT-639

WT_INSERT slots corrupted, test/format failure

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    Details

    • Type: Task
    • Status: Closed
    • Resolution: Fixed
    • Affects Version/s: None
    • Fix Version/s: WT1.6.5
    • Labels:

      Description

      Saw a core dump last night, when running against the WT-638 branch – it might be connected to that branch, but I don't think so.

      (gdb) where
      #0  0x000000000044dc67 in __bit_set (
          bitf=0x8044222a8 "wivk??e?WoVn???}\226???\227Uf_?gz\233k?\233?ۦ宿g????f?{zw????m?\236?\231?yZo?\225???ݷiyj??i?v~??U?V????f\233\236\237?i??i???ݥ\225\225w?w?u?\237???k?vo?o??ޯ??\236?W??W??^Y??\237??\225?\177[\177\235?ݾy???w??[knZ??^?ߺ]\231\233{\225\231????[g~\231?o~u}??ݺ?\226?????????"..., 
          bit=18446744073709551612) at bitstring.i:99
      WT-1  0x000000000044dbef in __bit_setv (
          bitf=0x8044222a8 "wivk??e?WoVn???}\226???\227Uf_?gz\233k?\233?ۦ宿g????f?{zw????m?\236?\231?yZo?\225???ݷiyj??i?v~??U?V????f\233\236\237?i??i???ݥ\225\225w?w?u?\237???k?vo?o??ޯ??\236?W??W??^Y??\237??\225?\177[\177\235?ݾy???w??[knZ??^?ߺ]\231\233{\225\231????[g~\231?o~u}??ݺ?\226?????????"..., 
          entry=18446744073709551614, width=2 '\002', value=3 '\003')
          at bitstring.i:303
      WT-2  0x000000000044e741 in __bit_setv_recno (page=0x8044208e0, 
          recno=18446744073709551615, width=2 '\002', value=3 '\003')
          at bitstring.i:315
      WT-3  0x000000000044e3c5 in __rec_col_fix (session=0x80268b660, r=0x804603400, 
          page=0x8044208e0) at ../src/btree/rec_write.c:2331
      WT-4  0x00000000004494fc in __wt_rec_write (session=0x80268b660, 
          page=0x8044208e0, salvage=0x0, flags=0) at ../src/btree/rec_write.c:317
      

      What's happening is that we're reconciling a page, and there's a record on the page's update list that has an invalid record number.

      Inside the page->modify->update skip list, I see:

      $1775 = {upd = 0x80243b200, u = {recno = 646, key = {offset = 646, 
            size = 0}}, next = 0x80243b1f0}
      $1776 = {upd = 0x805844380, u = {recno = 651, key = {offset = 651, 
            size = 0}}, next = 0x805844370}
      $1777 = {upd = 0x805c3b540, u = {recno = 18446744073709551615, key = {
            offset = 4294967295, size = 4294967295}}, next = 0x80385a5b0}
      $1778 = {upd = 0x80243b740, u = {recno = 657, key = {offset = 657, 
            size = 0}}, next = 0x80381f050}
      $1779 = {upd = 0x80243ba80, u = {recno = 658, key = {offset = 658, 
            size = 0}}, next = 0x8024401d0}
      

      $1777 has a recno of UINT64_MAX, and offset/size values of UINT32_MAX, but the WT_UPDATE structure looks reasonable:

      (gdb) p *(WT_UPDATE *)0x805c3b540
      $1791 = {size = 1, txnid = 4007, next = 0x0}
      

      Entry $1777 isn't at the head of any of the skip-list chains, it's right in the middle of all of them. (That's why I don't think this has anything to do with the WT-638 branch, this entry was pushed into the list long after the list itself was allocated).

      I would think that a recno of UINT64_MAX would be a smoking gun, but I can't find it. There's a little dance in __wt_btcur_insert():

      /*
       * If WT_CURSTD_APPEND is set, insert a new record (ignoring
       * the application's record number).  First we search for the
       * maximum possible record number so the search ends on the
       * last page.  The real record number is assigned by the
       * serialized append operation.
       */
      if (F_ISSET(cursor, WT_CURSTD_APPEND))
              cbt->iface.recno = UINT64_MAX;
       
      WT_ERR(__wt_col_search(session, cbt, 1));
       
      if (F_ISSET(cursor, WT_CURSTD_APPEND))
              cbt->iface.recno = 0;
      

      but I don't see how it's possible for the recno to be set incorrectly – imagine that we get WT_RESTART from __wt_col_search(), the next time through the loop we should still have WT_CURSTD_APPEND set.

      Here's the config that saw this error:

      ############################################
      #  RUN PARAMETERS
      ############################################
      bitcnt=2
      cache=40
      compression=snappy
      data_extend=0
      data_source=file
      delete_pct=0
      # dictionary not applicable to this run
      file_type=fixed-length column-store
      hot_backups=0
      # huffman_key not applicable to this run
      # huffman_value not applicable to this run
      insert_pct=41
      internal_key_truncation=0
      internal_page_max=17
      key_gap=17
      # key_max not applicable to this run
      # key_min not applicable to this run
      leaf_page_max=12
      ops=5000
      # prefix not applicable to this run
      # repeat_data_pct not applicable to this run
      reverse=0
      rows=1000
      runs=0
      split_pct=43
      threads=31
      # value_max not applicable to this run
      # value_min not applicable to this run
      # wiredtiger_config not applicable to this run
      write_pct=20
      ############################################
      

      @michaelcahill, any ideas?

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              • Assignee:
                keith.bostic Keith Bostic
                Reporter:
                keith.bostic Keith Bostic
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                • Created:
                  Updated:
                  Resolved: