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  1. WiredTiger
  2. WT-210

Sync request race

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    Details

    • Type: Task
    • Status: Closed
    • Resolution: Done
    • Affects Version/s: None
    • Fix Version/s: WT1.2
    • Component/s: None
    • Labels:
      None

      Description

      Automated testing today found a race in the new code that puts eviction requests into the session handle.

      A thread was waiting for a sync:

      Thread 2 (Thread 0x7f693ffff700 (LWP 25683)):
      #0  0x00000030f380b3dc in pthread_cond_wait@@GLIBC_2.3.2 ()
         from /lib64/libpthread.so.0
      WT-1  0x000000000040eb7c in __wt_cond_wait (session=0x1db44d0, 
          cond=0x7f6920012980) at ../src/os_posix/os_mtx.c:68
      WT-2  0x0000000000424036 in __wt_session_serialize_func (session=0x1db44d0, 
          op=WT_SERIAL_EVICT, func=0x419c57 <__wt_sync_file_serial_func>, 
          args=0x7f693fffeb20) at ../src/include/serial.i:54
      WT-3  0x0000000000424086 in __wt_sync_file_serial (session=0x1db44d0, syncop=1)
          at ../src/include/serial_funcs.i:321
      WT-4  0x0000000000424a0a in __wt_cache_flush (session=0x1db44d0, op=1)
          at ../src/btree/bt_sync.c:307
      

      But the eviction thread was sleeping, believing it had handled all requests:

      Thread 5 (Thread 0x7f694d39b700 (LWP 25667)):
      #0  0x00000030f380b3dc in pthread_cond_wait@@GLIBC_2.3.2 ()
         from /lib64/libpthread.so.0
      WT-1  0x000000000040eb7c in __wt_cond_wait (session=0x1db39e0, cond=0x1dc1d70)
          at ../src/os_posix/os_mtx.c:68
      WT-2  0x0000000000419e96 in __wt_cache_evict_server (arg=0x1db3210)
          at ../src/btree/bt_evict.c:273
      

      (gdb) print *((WT_CONNECTION_IMPL *)$2)->cache
      $4 = {..., sync_request = 99, sync_complete = 99}
      

      I'm about to push a change that should catch this, but I can't yet see how where the race is happening.

      Michael.

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              • Assignee:
                Unassigned
                Reporter:
                michael.cahill Michael Cahill
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                • Created:
                  Updated:
                  Resolved: