浅谈数据库死锁故障的分析过程。

转载自品略图书馆  http://www.pinlue.com/article/2020/07/1613/4911032273458.html

 

导读：客户的监控告警频繁提示系统xx数据库死锁增长个数高于当前阈值_当前值1.00。下面是详细的故障分析诊断过程，以及详细的解决方案描述。

本文分为三部分：

• 1.背景概述

• 2.故障分析

• 3.根本解决方案及建议

 

1. 背景概述

 

客户的监控告警频繁提示系统xx数据库死锁增长个数高于当前阈值_当前值1.00。下面是详细的故障分析诊断过程，以及详细的解决方案描述。

 

 

2. 故障分析

 

2.1 故障现象登录到系统，从数据库到alert日志可以发现的确存在很多ORA-60的信息，截取部分如下：

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2020-04-23T19:32:00.644961+08:00XXXDB(4):ORA-00060: Global Enqueue Services Deadlock detected. See Note 60.1 at My Oracle for Troubleshooting ORA-60 Errors. More info in file /oracle/app/oracle/diag/rdbms/z1d1v19c/xxxxxxxx2/trace/xxxxxxxx2_ora_127408.trc.2020-04-23T19:32:01.000382+08:00Dumping diagnostic data in directory=[cdmp_20200423193200], requested by (instance=2, osid=127408), summary=[abnormal process termination].2020-04-23T19:32:54.093147+08:00XXXDB(4):ORA-00060: Global Enqueue Services Deadlock detected. See Note 60.1 at My Oracle for Troubleshooting ORA-60 Errors. More info in file /oracle/app/oracle/diag/rdbms/z1d1v19c/xxxxxxxx2/trace/xxxxxxxx2_ora_127383.trc.2020-04-23T19:32:54.289460+08:00Dumping diagnostic data in directory=[cdmp_20200423193254], requested by (instance=2, osid=127383), summary=[abnormal process termination].2020-04-23T19:32:57.576079+08:00XXXDB(4):ORA-00060: Global Enqueue Services Deadlock detected. See Note 60.1 at My Oracle for Troubleshooting ORA-60 Errors. More info in file /oracle/app/oracle/diag/rdbms/z1d1v19c/xxxxxxxx2/trace/xxxxxxxx2_ora_124482.trc.

 

2.2 故障根源

查看trc内容，发现是自身导致的阻塞，几个trc都类似，下面截取其中一个trc跟踪日志的关键内容：

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*** 2020-04-23T19:32:00.644695+08:00 (XXXDB(4))*** SESSION ID:(7989.26294) 2020-04-23T19:32:00.644756+08:00*** CLIENT ID:() 2020-04-23T19:32:00.644762+08:00*** SERVICE NAME:(XXXDB) 2020-04-23T19:32:00.644767+08:00*** MODULE NAME:(oracle@xxxxxxxxdb2) 2020-04-23T19:32:00.644772+08:00*** ACTION NAME:() 2020-04-23T19:32:00.644777+08:00*** CLIENT DRIVER:() 2020-04-23T19:32:00.644781+08:00*** CONTAINER ID:(4) 2020-04-23T19:32:00.644785+08:00 Single resource deadlock: blocking enqueue which blocks itself, f 0Granted global enqueue 0xaf1cabb50----------enqueue 0xaf1cabb50------------------------lock version     : 137621Owner inst       : 2grant_level      : KJUSERNLreq_level        : KJUSERPWbast_level       : KJUSERNLnotify_func      : noneresp             : 0x5bf1f1c38procp            : 0xb069785a0pid              : 127405proc version     : 580oprocp           : (nil)opid             : 127405group lock owner : 0xb5aaec910possible pid     : 127405xid              : C1000-0002-000FC6D3dd_time          : 10.0 secsdd_count         : 0timeout          : 60.0 secsOn_timer_q?      : YOn_dd_q?         : Ysec since mv2grQ : N/Alock_state       : OPENING CONVERTINGast_flag         : 0x0flags            : 0x0Open Options     : KJUSERDEADLOCKConvert options  : KJUSERGETVALUEHistory          : FREE > KJLALC > REF_RES > LOC_AST > CLOSE > FREE > KJLALC > REF_RES > GR2CVTMsg_Seq          : 0x0res_seq          : 10845078valblk           : 0x00000000000000000000000000000000 .user session for deadlock lock 0xaf1cabb50  sid: 7867 ser: 47087 audsid: 210608 user: 103/ZJY  pdb: 4/XXXDB    flags: (0x41) USR/- flags2: (0x40009) -/-/INC    flags_idl: (0x1) status: BSY/-/-/- kill: -/-/-/-  pid: 193 O/S info: user: grid, term: UNKNOWN, ospid: 127405    image: oracle@xxxxxxxxdb2  client details:    O/S info: user: , term: , ospid: 1234    machine: ltyglapp01 program: oracle@xxxxxxxxdb2    application name: oracle@xxxxxxxxdb2, hash value=420857658  current SQL:  delete from tx_xxxx_xxxxx_xxxx where 1=1  and FTOOL_CODE="X019541" and T8_SYS_ADTYPE_ID=1 and T8_SYS_PORTFOL_ID=100148 and SETTLE_DATE >="20200423" and isaccount != 1   and account_type=3 and (BOND_MARKET=1 or BOND_MARKET is null )Requesting global enqueue 0xb1ceb9110----------enqueue 0xb1ceb9110------------------------lock version     : 534003Owner inst       : 2grant_level      : KJUSERCWreq_level        : KJUSERPWbast_level       : KJUSERNLnotify_func      : noneresp             : 0x5bf1f1c38procp            : 0xb069bd4b0pid              : 127408proc version     : 1615oprocp           : (nil)opid             : 127408group lock owner : 0xb4aa785e8possible pid     : 127408xid              : C2000-0002-0002D8DDdd_time          : 0.0 secsdd_count         : 0timeout          : -6670697.0 secsOn_timer_q?      : NOn_dd_q?         : Nsec since mv2grQ : 0lock_state       : CONVERTINGast_flag         : 0x0flags            : 0x1Open Options     : KJUSERDEADLOCKConvert options  : KJUSERGETVALUEHistory          : REF_RES > LOC_AST > CLOSE > FREE > KJLALC > REF_RES > GR2CVT > LOC_AST_FG > LOC_ASTMsg_Seq          : 0x0res_seq          : 10845078valblk           : 0x00000000000000000000000000000000 .user session for deadlock lock 0xb1ceb9110  sid: 7989 ser: 26294 audsid: 210609 user: 103/ZJY  pdb: 4/XXXDB    flags: (0x41) USR/- flags2: (0x40009) -/-/INC    flags_idl: (0x1) status: BSY/-/-/- kill: -/-/-/-  pid: 194 O/S info: user: grid, term: UNKNOWN, ospid: 127408    image: oracle@xxxxxxxxdb2  client details:    O/S info: user: , term: , ospid: 1234    machine: ltyglapp01 program: oracle@xxxxxxxxdb2    application name: oracle@xxxxxxxxdb2, hash value=420857658  current SQL:  delete from tx_xxxx_xxxxx_xxxx where 1=1  and FTOOL_CODE="112094455" and T8_SYS_ADTYPE_ID=24 and T8_SYS_PORTFOL_ID=100148 and SETTLE_DATE >="20200423" and isaccount != 1  and (BOND_MARKET=3 or BOND_MARKET is null ) and relation_no="100912"----------resource 0x5bf1f1c38----------------------resname       : [0x11ecf][0x0],[TM][ext 0xfffdbbf8,0x0][domid 0x4]

 

可以发现都是delete from tx_xxxx_xxxxx_xxxx这张表，死锁现象是Single resource deadlock，而且TYPE是TM，综合分析这种现象，大多就是外键没有索引导致。

c. For single resource deadlock on TM enqueue, missing foreign key index is often the cause, please check case 3 for the solution.

进一步获取建表语句查看约束部分，发现只有主键，没有外键：

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select dbms_metadata.get_ddl("TABLE","TX_XXXX_XXXXX_XXXX","ZJY") from dual;…      "TEMPACCRUBLN" NUMBER(22,4) DEFAULT 0,         CONSTRAINT "PK_TX_XXXX_XXXXX_XXXX" PRIMARY KEY ("ID")  USING INDEX PCTFREE 10 INITRANS 2 MAXTRANS 255 COMPUTE STATISTICS  STORAGE(INITIAL 65536 NEXT 1048576 MINEXTENTS 1 MAXEXTENTS 2147483645  PCTINCREASE 0 FREELISTS 1 FREELIST GROUPS 1  BUFFER_POOL DEFAULT FLASH_CACHE DEFAULT CELL_FLASH_CACHE DEFAULT)  TABLESPACE "ZJYDATA"  ENABLE…

 

查询ZJY用户下所有存在外键的表：

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STAT TABLE_NAME                     CON                  IDX---- ------------------------------ -------------------- --------------------ok   T8_ACC_XXXXXXX                 TX_XXXXX_XXXX_ID    TX_XXXXX_XXXX_ID**** T8_SHIBOR_ACC_XXXXXXX          TX_XXXXX_XXXX_ID**** T8_CUSTOM_ACC_XXXXXXX          TX_XXXXX_XXXX_ID**** T8_IMPAWN_ACC_XXXXXXX          TX_XXXXX_XXXX_ID**** T8_FUND_ACC_XXXXXXX            TX_XXXXX_XXXX_ID**** T8_LENDING_ACC_XXXXXXX         TX_XXXXX_XXXX_ID**** T8_BOND_ACC_XXXXXXX            TX_XXXXX_XXXX_ID**** T8_BUYOUT_ACC_XXXXXXX          TX_XXXXX_XXXX_ID

 

进一步分析，其中T8_BOND_ACC_XXXXXXX的外键就是引用了TX_XXXX_XXXXX_XXXX的主键ID列：

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select dbms_metadata.get_ddl("TABLE","T8_BOND_ACC_XXXXXXX","ZJY") from dual; REFERENCES "ZJY"."TX_XXXX_XXXXX_XXXX" ("ID") ON DELETE CASCADE ENABLE

 

2.3 故障处置

业务闲时，在T8_BOND_ACC_XXXXXXX表的外键列TX_XXXXX_XXXX_ID上创建索引，再观察告警情况。

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create index TX_XXXXX_XXXX_ID on T8_BOND_ACC_XXXXXXX(TX_XXXXX_XXXX_ID) online;

 

注：上面是示范创建语句，具体创建索引的语句，比如是否采用online，是否使用并行等参照行里运维具体规范。

3. 根本解决方案及建议

 

虽然本次告警信息未发现其他表的全局死锁问题，但从Oracle的设计层面来看，建议在在所有7个表的外键列上都创建对应的索引，防止后续在其他表大量DML时出现同类问题。

此外，复盘的时候发现，trc跟踪日志的这一部分信息：

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----------resource 0x5bf1f1c38----------------------resname       : [0x11ecf][0x0],[TM][ext 0xfffdbbf8,0x0][domid 0x4]

 

这里的[0x11ecf]转换为10进制，就是对应的外键无索引对象的object_id。