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Oracle 19c Top event show “dispatcher listen timer” ?

今天在调试我的oracle数据库巡检脚本odbhc时,发现一套19c rac 测试库的top 1 event为 “dispatcher listen timer” , 影响脚本的显示,该数据库并没有配置共享会话模式,实际上是一个idle wait event算是AWR统计类Bug 19865595 , 后期版本已修复。

现象:

BEG_TIME         ELAPSED_SECS CPU_COUNT DBTIME           EVENT_NAME                                    WAITS waited(sec)      avg(ms)      DBTIME_PCT ELAPSE WAIT_CLASS
---------------- ------------ --------- ---------------- ---------------------------------------- ---------- ---------------- ------------ ---------- ------ --------------------
11-26 05:00              1005         6               12 dispatcher listen timer                           0            1,022        -1.00   8329.1%   17.0% Network
                         1005                            gc cr block 2-way                             60739               11         0.00     91.6%    0.2% Cluster
                         1005                            DB CPU                                            0               11         0.00     85.6%    0.2% DB CPU
                         1005                            control file sequential read                  16455                3         0.00     27.9%    0.1% System I/O
                         1005                            DFS lock handle                               12000                3         0.00     23.5%    0.0% Other

11-26 04:00              3599         6               42 dispatcher listen timer                           0            3,600        -4.00   8621.0%   16.7% Network
                         3599                            gc cr block 2-way                            223694               40         0.00     96.1%    0.2% Cluster
                         3599                            DB CPU                                            0               36         0.00     87.0%    0.2% DB CPU
                         3599                            DFS lock handle                               48000               14         0.00     33.3%    0.1% Other
                         3599                            control file sequential read                  54827               12         0.00     28.3%    0.1% System I/O


SQL> @sed dispatcher
Show wait event descriptions matching %dispatcher%..

EVENT# EVENT_NAME                                              WAIT_CLASS           PARAMETER1                PARAMETER2                PARAMETER3                ENQUEUE_NAME                   REQ_REASON                       REQ_DESCRIPTION
------ ------------------------------------------------------- -------------------- ------------------------- ------------------------- ------------------------- ------------------------------ -------------------------------- ----------------------------------------------------------------------------------------------------
   387 alter system set dispatcher                             Administrative       waited
   392 dispatcher listen timer                                 Network              sleep time
  1452 dispatcher shutdown                                     Other                waited
   391 dispatcher timer                                        Idle                 sleep time

原因
因为配置了XDB dispatcher,虽然没有使用XDB feature.

解决方法

SQL> show parameter dispatchers

PARAMETER_NAME                                               TYPE        VALUE
------------------------------------------------------------ ----------- ----------------------------------------------------------------------------------------------------
dispatchers                                                  string      (PROTOCOL=TCP) (SERVICE=kunXDB)
max_dispatchers                                              integer


SQL> alter system set dispatchers='' scope=both;

测试

SQL> execute dbms_workload_repository.create_snapshot;

PL/SQL procedure successfully completed.

SQL> execute dbms_workload_repository.create_snapshot;

PL/SQL procedure successfully completed.


BEG_TIME         ELAPSED_SECS CPU_COUNT DBTIME           EVENT_NAME                                    WAITS waited(sec)      avg(ms)      DBTIME_PCT ELAPSE WAIT_CLASS
---------------- ------------ --------- ---------------- ---------------------------------------- ---------- ---------------- ------------ ---------- ------ --------------------
11-26 05:17                10         6                2 DB CPU                                            0                2         0.00     89.7%    3.5% DB CPU
                           10                            gc current block busy                           250                0         0.00      3.5%    0.1% Cluster
                           10                            log file parallel write                          81                0         1.00      3.4%    0.1% System I/O
                           10                            control file sequential read                    563                0         0.00      2.5%    0.1% System I/O
                           10                            gcs log flush sync                               48                0         1.00      1.7%    0.1% Other





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