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  1. WiredTiger
  2. WT-265

schema truncate of a table with an index unlocks a lock it doesn't hold

    • Type: Icon: Task Task
    • Resolution: Done
    • WT1.3
    • Affects Version/s: None
    • Component/s: None
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      This Python test script tries to abort because we're unlocking a lock that was never acquired.

      import wiredtiger, wttest
      class test_f(wttest.WiredTigerTestCase):
          # This test drops core. 
          def test_f(self):
              uri = "table:xxx"
                  'key_format=i,value_format=SiS,' +
                  'columns=(record,column2,column3,column4),' +
              cgname = 'colgroup:' + uri.split(":")[1]
              self.session.create(cgname + ':cgroup1', 'columns=(column2)')
              self.session.create(cgname + ':cgroup2', 'columns=(column3)')
              self.session.create(cgname + ':cgroup3', 'columns=(column4)')
              indxname = 'index:' + uri.split(":")[1]
              self.session.create(indxname + ':indx1', 'columns=(column2)')
              self.session.truncate(uri, None, None, None)
              self.session.drop(uri, None)
      if __name__ == '__main__':

      The problem is we're not acquiring a lock when opening the btree handle. Here's the stack to get the btree handle:

      #0  __wt_session_get_btree (session=0x8030de3d0, uri=0x801012ec0 "file:xxx_indx1.wti", cfg=0x0, 
          flags=2) at ../src/session/session_btree.c:178
      WT-1  0x0000000801ec533e in __open_index (session=0x8030de3d0, table=0x800f87600, 
          uri=0x800ea7b08 "index:xxx:indx1", 
          idxconf=0x8010d5190 "columns=(column2),filename=xxx_indx1.wti")
          at ../src/schema/schema_open.c:172
      WT-2  0x0000000801ec5966 in __wt_schema_open_index (session=0x8030de3d0, table=0x800f87600, 
          idxname=0x0, len=0) at ../src/schema/schema_open.c:305
      WT-3  0x0000000801ecbbbb in __truncate_table (session=0x8030de3d0, name=0x8030c117a "xxx")
          at ../src/schema/schema_truncate.c:68
      WT-4  0x0000000801ecbd99 in __wt_schema_truncate (session=0x8030de3d0, uri=0x8030c1174 "table:xxx", 
          cfg=0x7fffffffc6a0) at ../src/schema/schema_truncate.c:114
      WT-5  0x0000000801ecd53f in __session_truncate (wt_session=0x8030de3d0, 
          uri=0x8030c1174 "table:xxx", start=0x0, stop=0x0, config=0x0)
          at ../src/session/session_api.c:331

      I believe the problem is encapsulated in *open_index: early in the function we call *wt_session_get_btree() but which doesn't lock the btree's rwlock, and then at the end of the function we call __wt_session_release_btree which always attempts to unlock btree->rwlock.

            michael.cahill@mongodb.com Michael Cahill (Inactive)
            keith.bostic@mongodb.com Keith Bostic (Inactive)
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