[20171106]配置客户端连接注意.txt
--//在配置客户端连接时一般建议使用Net Manager工具,windows下调用执行Net Manager.
--//linux下执行 netmgr,这样能一定程度避免copy & paste的 错误.
--//我这里想说的是在连接类型选择上一定要注意,一般存在4中选择:
数据库默认设置
专用服务器
共享服务器
池中服务器.
--//最好明确设置那种模式,而不是选择"数据库默认设置"模式,这样会导致以后配置启用"共享服务器"出现问题.
--//最近我们生产系统就遭遇这样的问题,还是通过例子说明:
1.环境:
SYS@book> @ &r/ver1
PORT_STRING VERSION BANNER
------------------------------ -------------- --------------------------------------------------------------------------------
x86_64/Linux 2.4.xx 11.2.0.4.0 Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production
--//我在我的client配置如下:
R:>cat tnsnames.ora
# tnsnames.ora Network Configuration File: r: nsnames.ora
# Generated by Oracle configuration tools.
BOOK =
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.100.78)(PORT = 1521))
)
(CONNECT_DATA =
(SERVICE_NAME = book)
)
)
BOOK1 =
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.100.78)(PORT = 1521))
)
(CONNECT_DATA =
(SERVER = DEDICATED)
(SERVICE_NAME = book)
)
)
BOOK2 =
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.100.78)(PORT = 1521))
)
(CONNECT_DATA =
(SERVER = SHARED)
(SERVICE_NAME = book)
)
)
--//注第一种情况连接串BOOK就是"数据库默认设置".没有明确参数SERVER的值.许多开发包括我们下发的程序都是这样设置的.
2.我开启共享服务模式:
SYS@book> show parameter dispatchers
NAME TYPE VALUE
---------------- -------- -------------------------------------
dispatchers string (PROTOCOL=TCP) (SERVICE=book,bookXDB)
max_dispatchers integer
SYS@book> show parameter shared_server
NAME TYPE VALUE
---------------------- ------- -----
max_shared_servers integer 1
shared_server_sessions integer
shared_servers integer 1
--//我打开2个会话:
R:>sqlplus scott/book@book
R:>sqlplus scott/book@book
--//打开另外会话以sys用户执行如下(session 3):
--//session 3:
SELECT s.sid
,s.serial#
,p.spid
,p.pid
,p.serial# p_serial#
,s.SERVER
,s.status
,s.username
, 'alter system kill session '''
|| s.sid
|| ','
|| s.serial#
|| ''''
|| ' immediate;'
c50
FROM v$session s, v$process p
WHERE s.paddr = p.addr and s.username='SCOTT';
SID SERIAL# SPID PID P_SERIAL# SERVER STATUS USERNAME C50
----- ------- ------ ------- ---------- --------- -------- ---------- --------------------------------------------------
262 241 5750 19 1 NONE INACTIVE SCOTT alter system kill session '262,241' immediate;
263 77 5750 19 1 NONE INACTIVE SCOTT alter system kill session '263,77' immediate;
--//你可以发现现在2个会话没有执行任何语句,status='INACTIVE',server='NONE'.如果你在其中会话执行语句.
--//session 1:
select count(*) from emp,emp,emp,emp,emp,emp,emp,emp;
--//session 3:
SID SERIAL# SPID PID P_SERIAL# SERVER STATUS USERNAME C50
----- ------- ------ ------- ---------- --------- -------- ---------- --------------------------------------------------
263 77 5750 19 1 NONE INACTIVE SCOTT alter system kill session '263,77' immediate;
262 241 5752 20 1 SHARED ACTIVE SCOTT alter system kill session '262,241' immediate;
--//你可以发现其中1个会话status从'INACTIVE'->'ACTIVE',server从'NONE'=>SHARED.
--//在sessiono 1没有执行结束时,在session 2执行:
SCOTT@book> select sysdate from dual ;
--//session 2会挂起,这个是因为我没有设置dispatchers参数D000进程太少.
--//如果这时在执行如下:
R:>sqlplus scott/book@book
SQL*Plus: Release 12.1.0.1.0 Production on Mon Nov 6 12:00:05 2017
Copyright (c) 1982, 2013, Oracle. All rights reserved.
ERROR:
ORA-28547: connection to server failed, probable Oracle Net admin error
3.重复测试看看awr报表:
--session 3:
exec dbms_workload_repository.create_snapshot();
--session 1:
select count(*) from emp,emp,emp,emp,emp,emp,emp,emp;
--session 2:
select sysdate from dual ;
--//等待结束.
--session 3:
exec dbms_workload_repository.create_snapshot();
--//查看awr报表.实际上根本看不出问题.
SYS@book> @ &r/wait
P1RAW P2RAW P3RAW P1 P2 P3 SID SERIAL# SEQ# EVENT STATE WAIT_TIME_MICRO SECONDS_IN_WAIT
---------------- ---------------- ---------------- ---------- ---------- ---------- ---------- ---------- ---------- ---------------------------------------- ------------------- --------------- ---------------
000000004D545300 0000000000000001 00 1297371904 1 0 262 241 77 SQL*Net message to client WAITED SHORT TIME 5 31
--//这个也是共享服务器模式的弊端.执行的语句必须很快完成,不然会影响别的会话执行sql语句.blog.itpub.net/267265/viewspace-2124172/
4.如果增加参数max_shared_servers,max_dispatchers数量:
SYS@book> alter system set max_shared_servers=6 scope=memory;
System altered.
SYS@book> alter system set max_dispatchers=10 scope=memory ;
System altered.
SYS@book> alter system set dispatchers='(PROTOCOL=TCP) (SERVICE=book,bookXDB)(dispatchers=6)' scope=memory;
System altered.
SYS@book> alter system register ;
System altered.
$ ps -lef | egrep "d00[0-9]_book|UI[D]"
F S UID PID PPID C PRI NI ADDR SZ WCHAN STIME TTY TIME CMD
0 S oracle 53333 1 0 80 0 - 61860 poll_s 14:45 ? 00:00:00 ora_d000_book
0 S oracle 53471 1 0 80 0 - 61827 poll_s 14:56 ? 00:00:00 ora_d001_book
0 S oracle 53473 1 0 80 0 - 61827 poll_s 14:56 ? 00:00:00 ora_d002_book
0 S oracle 53475 1 0 80 0 - 61827 poll_s 14:56 ? 00:00:00 ora_d003_book
0 S oracle 53477 1 0 80 0 - 61827 poll_s 14:56 ? 00:00:00 ora_d004_book
0 S oracle 53479 1 0 80 0 - 61827 poll_s 14:56 ? 00:00:00 ora_d005_book
--//依次打开3个会话:
R:>sqlplus scott/book@book
R:>sqlplus scott/book@book
R:>sqlplus scott/book@book
--//session 4:
SELECT s.sid
,s.serial#
,p.spid
,p.pid
,p.serial# p_serial#
,s.SERVER
,s.status
,s.username
,s.program
,p.program
, 'alter system kill session '''
|| s.sid
|| ','
|| s.serial#
|| ''''
|| ' immediate;'
c50
FROM v$session s, v$process p
WHERE s.paddr = p.addr and s.username='SCOTT';
SID SERIAL# SPID PID P_SERIAL# SERVER STATUS USERNAME PROGRAM PROGRAM C50
---------- ---------- ------ ------- ---------- --------- -------- -------- ------------ -------------------------- --------------------------------------------------
262 33 53471 29 4 NONE INACTIVE SCOTT sqlplus.exe oracle@xxxxxdg4 (D001) alter system kill session '262,33' immediate;
261 11 53473 30 2 NONE INACTIVE SCOTT sqlplus.exe oracle@xxxxxdg4 (D002) alter system kill session '261,11' immediate;
263 9 53479 33 1 NONE INACTIVE SCOTT sqlplus.exe oracle@xxxxxdg4 (D005) alter system kill session '263,9' immediate;
--//分别运行不同dispatchers上.这样就不会存在阻塞.
--//session 1:
SCOTT@book> select count(*) from emp,emp,emp,emp,emp,emp,emp,emp;
...
--//session 2:
SCOTT@book> select sysdate from dual ;
SYSDATE
-------------------
2017-11-06 15:11:00
--//session 3:
SCOTT@book> select sysdate from dual ;
SYSDATE
-------------------
2017-11-06 15:11:03
--//如果要增加S00N进程数量,修改参数:
SYS@book> alter system set shared_servers=4 scope=memory ;
System altered.
$ ps -lef | egrep "s00[0-9]_book|UI[D]"
F S UID PID PPID C PRI NI ADDR SZ WCHAN STIME TTY TIME CMD
0 S oracle 53335 1 3 80 0 - 60697 poll_s 14:45 ? 00:00:55 ora_s000_book
0 S oracle 53617 1 0 80 0 - 60565 poll_s 15:13 ? 00:00:00 ora_s001_book
0 S oracle 53619 1 0 80 0 - 60565 poll_s 15:13 ? 00:00:00 ora_s002_book
0 S oracle 53621 1 0 80 0 - 60565 poll_s 15:13 ? 00:00:00 ora_s003_book
5.总结:
1.讲了这么多,回到前面遇到的问题,可以发现如果client配置时使用数据库默认设置,在共享服务器存在的情况下,会优先使用.这样
如果应用配置存在问题,特别是2层应用模式,全部使用共享服务器模式连接数据库,这样如果某个sql执行很慢,就有可能阻塞业务的
正常运行,即使你配置足够的dispatchers.实际上如果你使用ezconnect连接也是共享模式.
参考链接: http://blog.itpub.net/267265/viewspace-2130292/=>[20161212]ezconnect与共享服务模式.txt
2.从上面的情况,说明在配置client时,需要选择正确的连接类型,而不是选择"数据库默认设置",以免造成不必要麻烦.
3.如果这样只能建立新的服务名,指派服务名使用共享服务器模式.
SYS@book> show parameter service
NAME TYPE VALUE
------------- ------ ---------------
service_names string BOOK, BOOKSHARE
SYS@book> alter system set dispatchers='(PROTOCOL=TCP) (SERVICE=bookshare,bookXDB)(dispatchers=6)' scope=memory;
System altered.
--//修改连接串如下:
BOOKS =
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.100.78)(PORT = 1521))
)
(CONNECT_DATA =
(SERVER = SHARED)
(SERVICE_NAME = bookshare)
)
)
R:>sqlplus scott/book@books
SCOTT@books> @ spid
SID SERIAL# SPID PID P_SERIAL# C50
---------- ---------- ------ ------- ---------- --------------------------------------------------
171 7 53621 37 1 alter system kill session '171,7' immediate;
--//session 4:
SELECT s.sid
,s.serial#
,p.spid
,p.pid
,p.serial# p_serial#
,s.SERVER
,s.status
,s.username
,s.program
,s.SERVICE_NAME
,p.program
, 'alter system kill session '''
|| s.sid
|| ','
|| s.serial#
|| ''''
|| ' immediate;'
c50
FROM v$session s, v$process p
WHERE s.paddr = p.addr and s.username='SCOTT';
SID SERIAL# SPID PID P_SERIAL# SERVER STATUS USERNAME PROGRAM SERVICE_NAME PROGRAM C50
--- ---------- ------ ------- ---------- --------- -------- -------- ----------- ------------ ---------------------- --------------------------------------------------
171 7 53727 32 6 NONE INACTIVE SCOTT sqlplus.exe BOOKSHARE oracle@xxxxxdg4 (D004) alter system kill session '171,7' immediate;
--//退出重新登录:
R:>sqlplus scott/book@book
SCOTT@book> @ spid
SID SERIAL# SPID PID P_SERIAL# C50
---------- ---------- ------ ------- ---------- --------------------------------------------------
184 19 53781 38 8 alter system kill session '184,19' immediate;
--//session 4:
SYS@book> /
SID SERIAL# SPID PID P_SERIAL# SERVER STATUS USERNAME PROGRAM SERVICE_NAME PROGRAM C50
--- ---------- ------ ------- ---------- --------- -------- -------- ----------- ------------ --------------- --------------------------------------------------
184 19 53781 38 8 DEDICATED INACTIVE SCOTT sqlplus.exe book oracle@gxqyydg4 alter system kill session '184,19' immediate;
--//这样连接模式就是专用服务器模式.