April 9, 2006
What's Mean "internal dummy connection"?
作者:eygle
出处:http://blog.eygle.com
升级到Apache2.2之后,在Apache的日志中经常看到大量的internal dummy connection日志:
| [root@systest logs]# tail -f access_log.20060409 |grep "internal dummy connection" ::1 - - "GET / HTTP/1.0" 200 68091 "-" "Apache/2.2.0 (Unix) PHP/5.1.2 (internal dummy connection)" ::1 - - "GET / HTTP/1.0" 200 68091 "-" "Apache/2.2.0 (Unix) PHP/5.1.2 (internal dummy connection)" ::1 - - "GET / HTTP/1.0" 200 68091 "-" "Apache/2.2.0 (Unix) PHP/5.1.2 (internal dummy connection)" ::1 - - "GET / HTTP/1.0" 200 68091 "-" "Apache/2.2.0 (Unix) PHP/5.1.2 (internal dummy connection)" ::1 - - "GET / HTTP/1.0" 200 68091 "-" "Apache/2.2.0 (Unix) PHP/5.1.2 (internal dummy connection)" ::1 - - "GET / HTTP/1.0" 200 68091 "-" "Apache/2.2.0 (Unix) PHP/5.1.2 (internal dummy connection)" |
不知道是什么意思?哪位能指点一下,谢谢:)
感谢留言网友的指点，这些信息的含义为:/* Create the request string. We include a User-Agent so that通过修改Apache的配置文件可以在日志中屏蔽这些信息:
* adminstrators can track down the cause of the odd-looking
* requests in their logs.
*/
srequest = apr_pstrcat(p, "GET / HTTP/1.0\r\nUser-Agent: ",
ap_get_server_version(),
" (internal dummy connection)\r\n\r\n", NULL);
SetEnvIf Remote_Addr "::1" dontlog参考链接:
CustomLog "|/usr/local/sbin/cronolog /opt/apache/logs/eygle_access_log.%Y%m%d" combined env=!dontlog
http://www.clusting.com/Apache/ApacheManual/logs.html http://svn.apache.org/viewvc/httpd/httpd/trunk/server/mpm_common.c?view=markup&pathrev=230808
Posted by eygle at 4:48 PM | Comments (5)
关于自动PGA管理的进一步探讨
作者:eygle
出处:http://blog.eygle.com
伴随自动PGA调整新特性的引入,Oracle随之引入了一系列新的视图,V$PGASTAT就是其中的一个.
在V$PGASTAT中有这样一个条目: global memory bound ,该条目记录数据库允许的最高PGA内存使用量,我们可以从不同的PGA参数设置来观察一下Oracle运行的PGA上限.
SQL> alter system set pga_aggregate_target=&Nm;
Enter value for nm: 10m
old 1: alter system set pga_aggregate_target=&Nm
new 1: alter system set pga_aggregate_target=10m
System altered.
Elapsed: 00:00:00.05
SQL> SET autotrace traceonly
SQL> SELECT DISTINCT * FROM t WHERE ROWNUM < 500000;
20000 rows selected.
Elapsed: 00:03:04.12
…….
SQL> SET autotrace off
SQL> SELECT sql_text, operation_type, POLICY, last_memory_used / 1024 / 1024,
2 last_execution, last_tempseg_size
3 FROM v$sql l, v$sql_workarea a
4 WHERE l.hash_value = a.hash_value
5 AND sql_text = 'SELECT DISTINCT * FROM t WHERE ROWNUM < 500000';
SQL_TEXT OPERATION_TYPE POLIC
-------------------------------------------------- ------------------ -----
LAST_MEMORY_USED/1024/1024 LAST_EXE LAST_TEMPSEG_SIZE
-------------------------- -------- -----------------
SELECT DISTINCT * FROM t WHERE ROWNUM < 500000 GROUP BY (SORT) AUTO
.548828125 206 PASSES 62914560
Elapsed: 00:00:00.02
SQL>
SQL> SELECT NAME, VALUE / 1024 / 1024 MB
2 FROM v$pgastat
3 WHERE NAME IN ('aggregate PGA target parameter', 'global memory bound');
NAME MB
---------------------------------------------------------------- ----------
aggregate PGA target parameter 10
global memory bound .5
SQL> alter system set pga_aggregate_target=&Nm;
Enter value for nm: 30M
old 1: alter system set pga_aggregate_target=&Nm
new 1: alter system set pga_aggregate_target=30M
System altered.
Elapsed: 00:00:00.05
SQL> SET autotrace traceonly
SQL> SELECT DISTINCT * FROM t WHERE ROWNUM < 500000;
20000 rows selected.
Elapsed: 00:00:53.30
………..
SQL> SET autotrace off
SQL> SELECT sql_text, operation_type, POLICY, last_memory_used / 1024 / 1024,
2 last_execution, last_tempseg_size
3 FROM v$sql l, v$sql_workarea a
4 WHERE l.hash_value = a.hash_value
5 AND sql_text = 'SELECT DISTINCT * FROM t WHERE ROWNUM < 500000';
SQL_TEXT OPERATION_TYPE POLIC LAST_MEMORY_USED/1024/1024
-------------------------------------------------- ------------------ ----- --------------------------
LAST_EXECUTION LAST_TEMPSEG_SIZE
-------------------- -----------------
SELECT DISTINCT * FROM t WHERE ROWNUM < 500000 GROUP BY (SORT) AUTO 1.48046875
6 PASSES 57671680
Elapsed: 00:00:00.02
SQL>
SQL> SELECT NAME, VALUE / 1024 / 1024 MB
2 FROM v$pgastat
3 WHERE NAME IN ('aggregate PGA target parameter', 'global memory bound');
NAME MB
---------------------------------------------------------------- ----------
aggregate PGA target parameter 30
global memory bound 1.5
Elapsed: 00:00:00.00
我们可以注意到,PGA的global memory bound会一直处在5%的PGA_AGGREGATE_TARGET参数设置,直到5% PGA_AGGREGATE_TARGET超过100M,然后global memory bound被限制为100M,也就是满足我们前文提到的:
对于串行操作，单个SQL操作能够使用的PGA内存按照以下原则分配：
MIN（5% PGA_AGGREGATE_TARGET，100MB）
注意,修改PGA_AGGREGATE_TARGET参数可以使用如下命令:
alter system set pga_aggregate_target=4096M ;
修改参数后,通常需要之行操作才能看到视图信息的变化:
SQL> SELECT NAME, VALUE / 1024 / 1024 MB
2 FROM v$pgastat
3 WHERE NAME IN ('aggregate PGA target parameter', 'global memory bound');
NAME MB
---------------------------------------------------------------- ----------
aggregate PGA target parameter 10
global memory bound .5
SQL> SELECT NAME, VALUE / 1024 / 1024 MB
2 FROM v$pgastat
3 WHERE NAME IN ('aggregate PGA target parameter', 'global memory bound');
NAME MB
---------------------------------------------------------------- ----------
aggregate PGA target parameter 20
global memory bound 1
SQL> SELECT NAME, VALUE / 1024 / 1024 MB
2 FROM v$pgastat
3 WHERE NAME IN ('aggregate PGA target parameter', 'global memory bound');
NAME MB
---------------------------------------------------------------- ----------
aggregate PGA target parameter 40
global memory bound 2
SQL> SELECT NAME, VALUE / 1024 / 1024 MB
2 FROM v$pgastat
3 WHERE NAME IN ('aggregate PGA target parameter', 'global memory bound');
NAME MB
---------------------------------------------------------------- ----------
aggregate PGA target parameter 1024
global memory bound 51.1992188
SQL> SELECT NAME, VALUE / 1024 / 1024 MB
2 FROM v$pgastat
3 WHERE NAME IN ('aggregate PGA target parameter', 'global memory bound');
NAME MB
---------------------------------------------------------------- ----------
aggregate PGA target parameter 4096
global memory bound 100
实际上这个100M的上限是受到了另外一个隐含参数的控制,该参数为_pga_max_size,该参数的缺省值为200M,单进程串行操作PGA的上限不能超过该参数的1/2.
SQL> SELECT x.ksppinm NAME, y.ksppstvl VALUE, x.ksppdesc describ
2 FROM SYS.x$ksppi x, SYS.x$ksppcv y
3 WHERE x.inst_id = USERENV ('Instance')
4 AND y.inst_id = USERENV ('Instance')
5 AND x.indx = y.indx
6 AND x.ksppinm LIKE '%&par%'
7 /
Enter value for par: pga_max
old 6: AND x.ksppinm LIKE '%&par%'
new 6: AND x.ksppinm LIKE '%pga_max%'
NAME VALUE DESCRIB
--------------------------------------------- ---------------- ---
_pga_max_size 209715200 Maximum size of the PGA memory for one process
如果我们修改该参数, global memory bound将可以突破100M的上限:
SQL> alter system set "_pga_max_size"=400M;
System altered.
……………………
SQL> SELECT NAME, VALUE / 1024 / 1024 MB
2 FROM v$pgastat
3 WHERE NAME IN ('aggregate PGA target parameter', 'global memory bound');
NAME MB
---------------------------------------------------------------- ----------
aggregate PGA target parameter 4096
global memory bound 200
对于PGA的控制,还有一系列的内部参数,列举如下,仅供参考:
SQL> l
1 SELECT x.ksppinm NAME, y.ksppstvl VALUE, x.ksppdesc describ
2 FROM SYS.x$ksppi x, SYS.x$ksppcv y
3 WHERE x.inst_id = USERENV ('Instance')
4 AND y.inst_id = USERENV ('Instance')
5 AND x.indx = y.indx
6* AND x.ksppinm LIKE '%&par%'
SQL> /
Enter value for par: smm
old 6: AND x.ksppinm LIKE '%&par%'
new 6: AND x.ksppinm LIKE '%smm%'
NAME VALUE DESCRIB
------------------------ ----- ----------------------------------------------------------------
_smm_auto_min_io_size 56 Minimum IO size (in KB) used by sort/hash-join in auto mode
_smm_auto_max_io_size 248 Maximum IO size (in KB) used by sort/hash-join in auto mode
_smm_auto_cost_enabled TRUE if TRUE, use the AUTO size policy cost functions
_smm_control 0 provides controls on the memory manager
_smm_trace 0 Turn on/off tracing for SQL memory manager
_smm_min_size 128 minimum work area size in auto mode
_smm_max_size 2560 maximum work area size in auto mode (serial)
_smm_px_max_size 15360 maximum work area size in auto mode (global)
_smm_bound 0 overwrites memory manager automatically computed bound
_smm_advice_log_size 0 overwrites default size of the PGA advice workarea history log
_smm_advice_enabled TRUE if TRUE, enable v$pga_advice
11 rows selected.
Posted by eygle at 4:47 PM | Comments (12)
经典重现
作者:eygle
出处:http://blog.eygle.com
很意外,这么快就看到了《Cost Based Oracle Fundamentals》这本书的电子版,网络的力量一直是惊人的.ERN的渠道也真是广泛.
Thomas Kyte这样评价这本书:
The insights that Jonathan provides into the workings
of the cost-based optimizer will make a DBA a better
designer, and a Developer a better SQL coder. Both
groups will become better troubleshooters.
— Thomas Kyte, VP (Public Sector), Oracle Corporation
|
这是一部艰深的经典之作,出版社也曾经不看好这本书的销量,曲高和寡总是难免.
也许能够真正从头到尾仔细通读这本书的人也恐怕不多.
不管怎样,能看到经典,总是有值得欣喜的地方,虽然,再一次侵犯了作者的版权.
经典之作,欣然而获,不亦快载?
Posted by eygle at 4:45 PM | Comments (1)