当删除oracle数据库user时发生row cache lock 等待事件

在oracle数据库中做的动作如下: drop user abc; hang住，等待事件为 row cache lock Hanganalyze   显示 ===============================================================================   Chains most likely to have caused the hang:  [a] Chain 1 Signature: 'enq: TT - contention'<='row cache lock' (cycle)   Chain 1 Signature Hash: 0x4a0d0d64  [b] Chain 2 Signature: 'row cache lock'<='row cache lock' (cycle)   Chain 2 Signature Hash: 0x75bdd0c  [c] Chain 3 Signature: 'row cache lock'<='row cache lock' (cycle)   Chain 3 Signature Hash: 0x75bdd0c   =============================================================================== Cycles:   ------------------------------------------------------------------------------- Chain 1: -------------------------------------------------------------------------------   Oracle session identified by:   {   instance: 1 (uouk2oas.uouk2oas1)   os id: 15866   process id: 197, oracle@uklpdufms01a (DW05)   session id: 1193   session serial #: 29877   }   is waiting for 'row cache lock' with wait info:   {   p1: 'cache id'=0xa   p2: 'mode'=0x0   p3: 'request'=0x3   time in wait: 1.731862 sec   heur. time in wait: 1871 min 58 sec   timeout after: 1.268138 sec   wait id: 489490   blocking: 6 sessions   current sql: BEGIN   SYS.KUPW$WORKER.MAIN('SYS_IMPORT_FULL_08', 'SYS', 0); >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>  END; impdp 导入数据操作阻止了drop user 的操作， 解决方法: 1:  取消impdp导数操作 2：重新运行drop user操作