[20210914]探究mutex的值 4.txt

[20210914]探究mutex的值 4.txt --//前几天做了做library_cache转储时,显示的mutex结构体里面相关信息的探究. Bucket: #=102650 Mutex=0x80528f40(0, 19, 0, 6) --//注：11g 下每个library cache bucket占用16字节，后面跟着mutex，mutex结构占用24字节，这样整个占用40字节。可以参考我前面 --//的测试 [20210524]分析library cache转储 3.txt --//大概猜测出第2,3数字表示gets,sleeps的数量.后面的dump显示总是6,不知道为什么我感觉应该对应mutex结构体的20~23字节. --//前面第1个数字,转储总是显示0,如果使用oradebug poke前面0~3,4-7字节非0,dump总是挂起.导致我无法猜测第1个数字表示什么. oradebug poke 0x0000000080528f40 4 0x00000001 oradebug poke 0x0000000080528f44 4 0x00000002 --//前面的测试有点乱,重新测试看看. 1.环境: 1.环境： SCOTT@book> @ 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 SYS@book> alter system set session_cached_cursors=0 scope=spfile; System altered. --//重启略,设置目的主要保证每次都是软解析,这样都会访问library cache mutex. SCOTT@book> select * from dept where deptno=20;     DEPTNO DNAME          LOC ---------- -------------- -------------         20 RESEARCH       DALLAS --//执行5次以上。 SCOTT@book> @ hash HASH_VALUE SQL_ID        CHILD_NUMBER HASH_HEX ---------- ------------- ------------ ---------   95129850 80baj2c2ur47u            0   5ab90fa --//95129850%131072 = 102650,确定library cache mutex 地址如下,通过转储library cache,过程略. oradebug setmypid oradebug dump library_cache 10; --//检查转储,搜索Bucket: #=102650,发现如下: Bucket: #=102650 Mutex=0x80528f40(0, 6, 0, 6) 2.建立测试脚本: $ cat mutex_gets.sh #! /bin/bash # test mutex gets change # # argv1=mutex_address # argv2=sleep secoonds # sqlplus -s -l / as sysdba <<EOF|ts.awk & oradebug setmypid $(seq 6 | xargs -IQ echo -e "oradebug peek 0x${1} 24\nhost sleep $2\n") quit EOF sqlplus -s -l scott/book <<EOF | ts.awk & set head off feedback off $(seq 5 | xargs -IQ echo -e "select * from dept where deptno=20;\nhost sleep $2\n") quit EOF #strace -Ttt -f -p $! -o /tmp/mutex.txt & #strace -Ttt -f -p $! -o /tmp/mutex.txt -e select,sched_yield & $ . mutex_gets.sh 80528F40 1 | grep 080528F40 [2021-09-14 09:36:34] [080528F40, 080528F58) = 00000000 00000000 00000045 00000000 000190FA 00000000 [2021-09-14 09:36:35] [080528F40, 080528F58) = 00000000 00000000 00000046 00000000 000190FA 00000000 [2021-09-14 09:36:36] [080528F40, 080528F58) = 00000000 00000000 00000047 00000000 000190FA 00000000 [2021-09-14 09:36:37] [080528F40, 080528F58) = 00000000 00000000 00000048 00000000 000190FA 00000000 [2021-09-14 09:36:38] [080528F40, 080528F58) = 00000000 00000000 00000049 00000000 000190FA 00000000 [2021-09-14 09:36:39] [080528F40, 080528F58) = 00000000 00000000 00000049 00000000 000190FA 00000000 --//因为我设置session_cached_cursors=0,每次都是软解析,各样每次间隔1秒gets增加1,可以看出peek 24字节中8-11字节表示gets的数量. SYS@book> oradebug setmypid Statement processed. SYS@book> oradebug peek 0x80528f40 24 [080528F40, 080528F58) = 00000000 00000000 00000049 00000000 000190FA 00000000 --//0x49 = 73 SYS@book> oradebug dump library_cache 8; Statement processed. SYS@book> oradebug peek 0x80528f40 24 [080528F40, 080528F58) = 00000000 00000000 0000004A 00000000 000190FA 00000000 --//0x4a = 74 --//检查转储: Bucket: #=102650 Mutex=0x80528f40(0, 74, 0, 6) --//74 = 0x4a   LibraryHandle:  Address=0x7d3c9600 Hash=5ab90fa LockMode=N PinMode=0 LoadLockMode=0 Status=VALD     ObjectName:  Name=select * from dept where deptno=20       FullHashValue=e8ec445edab00042802d511305ab90fa Namespace=SQL AREA(00) Type=CURSOR(00) Identifier=95129850 OwnerIdn=83     Statistics:  InvalidationCount=0 ExecutionCount=70 LoadCount=2 ActiveLocks=1 TotalLockCount=70 TotalPinCount=1     Counters:  BrokenCount=1 RevocablePointer=1 KeepDependency=1 Version=0 BucketInUse=69 HandleInUse=69 HandleReferenceCount=0     Concurrency:  DependencyMutex=0x7d3c96b0(0, 2, 0, 0) Mutex=0x7d3c9740(86, 301, 0, 6)     Flags=RON/PIN/TIM/PN0/DBN/[10012841]     WaitersLists:       Lock=0x7d3c9690[0x7d3c9690,0x7d3c9690]       Pin=0x7d3c9670[0x7d3c9670,0x7d3c9670]       LoadLock=0x7d3c96e8[0x7d3c96e8,0x7d3c96e8]     Timestamp:  Current=09-14-2021 09:20:40     HandleReference:  Address=0x7d3c97d0 Handle=(nil) Flags=[00]     ReferenceList:       Reference:  Address=0x7d06d128 Handle=0x7d6c0cc8 Flags=ROD[21]     LibraryObject:  Address=0x7d06ee18 HeapMask=0000-0001-0001-0000 Flags=EXS[0000] Flags2=[0000] PublicFlags=[0000]       DataBlocks:         Block:  #='0' name=KGLH0^5ab90fa pins=0 Change=NONE           Heap=0x7c185b68 Pointer=0x7d06eeb8 Extent=0x7d06ed98 Flags=I/-/P/A/-/-           FreedLocation=0 Alloc=2.437500 Size=3.976562 LoadTime=22924574690       ChildTable:  size='16'         Child:  id='0' Table=0x7d06fcc8 Reference=0x7d06f708 Handle=0x7d5e6c68     NamespaceDump:       Parent Cursor:  sql_id=80baj2c2ur47u parent=0x7d06eeb8 maxchild=1 plk=y ppn=n --//你可以发现转储library cache ,对应的gets也增加1. --//本来想继续描述sleep的情况的,发现一些我无法理解的情况,先放一放.