1、问题发现
检查客户数据库的时候发现存在大量死锁的情况
Thread 1 advanced to log sequence 257 (LGWR switch) Current log# 16 seq# 257 mem# 0: /oradata/Oracle/online_log/redo16_01.log Current log# 16 seq# 257 mem# 1: /oradata/oracle/online_log/redo16_02.log Tue Jul 03 10:14:53 2018 Archived Log entry 385 added for thread 1 sequence 256 ID 0x59dc8ffa dest 1: Tue Jul 03 10:14:53 2018 LNS: Standby redo logfile selected for thread 1 sequence 257 for destination LOG_ARCHIVE_DEST_2 Tue Jul 03 10:19:39 2018 opiodr aborting process unknown ospid (23762) as a result of ORA-609 Tue Jul 03 10:51:18 2018 ORA-00060: Deadlock detected. More info in file /u01/oracle/diag/rdbms/orcl/orcl/trace/orcl_ora_25846.trc. Tue Jul 03 10:54:01 2018 ORA-00060: Deadlock detected. More info in file /u01/oracle/diag/rdbms/orcl/orcl/trace/orcl_ora_14067.trc. Tue Jul 03 11:02:28 2018 ORA-00060: Deadlock detected. More info in file /u01/oracle/diag/rdbms/orcl/orcl/trace/orcl_ora_20781.trc. Tue Jul 03 11:21:13 2018 Thread 1 cannot allocate new log, sequence 258 Private strand flush not complete
查看trace文件orcl_ora_25846.trc结果如下
Deadlock graph: ---------Blocker(s)-------- ---------Waiter(s)--------- Resource Name process session holds waits process session holds waits TX-026e0020-000001a5 147 4468 X 385 241 S TM-0007fd6c-00000000 385 241 X 147 4468 SX session 4468: DID 0001-0093-000001FEsession 241: DID 0001-0181-00000014 session 241: DID 0001-0181-00000014session 4468: DID 0001-0093-000001FE Rows waited on: Session 4468: obj - rowid = 0007FD6C - AAAAAAAAAAAAAAAAAA (dictionary objn - 523628, file - 0, block - 0, slot - 0) Session 241: no row ----- Information for the OTHER waiting sessions ----- Session 241: sid: 241 ser: 425 audsid: 24705000 user: 160/FD14 flags: (0x45) USR/- flags_idl: (0x1) BSY/-/-/-/-/- flags2: (0x40009) -/-/INC pid: 385 O/S info: user: oracle, term: UNKNOWN, ospid: 20781 image: oracle@dbserver1 client details: O/S info: user: TL3050, term: TL3050-WZ, ospid: 5300:5348 machine: WORKGROUPTL3050-WZ program: CWV4.2.8.337_20131204.exe application name: CWV4.2.8.337_20131204.exe, hash value=580982453 current SQL: insert into pzd2018 (UNI_NO,ORD,STYPE,STYPE2,SNO,SYEAR,SMONTH,RMONTH,SDAY,SABSTRACT,OPERATOR,J_AMOUNT,D_AMOUNT,SUBJ,SUBJNAME, OPP_SUBJ,SRC_CODE,ECO_CODE,SRC_PAYTYPE,SRC_BUTYPE,ECO_TYPE,ECO_WARRANT,PRJ_ORDER,PRJ_NAME,OPP_PRJ,CLR_ORDER, UNIT_CODE,SPECCODE,CONTRACT_NO,CAR_NO,OLPAY_SNO,schedule_date,WB_TYPE,WB_JNUM,WB_DNUM,WB_FACT,NUM_TYPE, NUM_JNUM,NUM_DNUM,NUM_PRICE,CAP_NO,CAP_ORD,JSFS_CODE,ZPH,BUSS_DATE,OTHER_UNIT,ACNT,BANKNO,ADDRESS1,ADDRESS2, TNO,ACT_NO,BU_CODE,T_CODE,RESBU_CODE,RESBU_AMT,SPECCODE1,SPECCODE2,SPECCODE3,SPECCODE4,RES_S1, RES_S2,RES_S3,RES_S4,ASSET_SUBJ,TAX_NO,SRC_NAME,ADDITION,UNI_PRJ_ORDER,Clr_Bu_Code, Source_Type,Source,SrKey,SMark,Uni_Prj_Name,clrsno,input_name,check_name,attach_act, attach_act_no,pz_attr,src_type,zj_type,ref_uni_no,charge_sno,charge_name,src_lkx,order_type,c ----- End of information for the OTHER waiting sessions ----- Information for THIS session: ----- Current SQL Statement for this session (sql_id=9ktt36bsngnyx) ----- insert into pz2018 (UNI_NO,STYPE,STYPE2,SNO,SYEAR,SMONTH,RMONTH,SDAY,INPUT_NAME,CHECK_NAME,COMP_NAME,COMP_NAME2, ADDITION,CHILDNUM,J_AMOUNT,D_AMOUNT,SSTATE,REMARK,PZ_ATTR) values(:1,:2,:3,:4,:5,:6,:7,:8,:9,:10,:11,:12,:13,:14,:15,:16,:17,:18,:19) ===================================================
2、问题分析
可以看出来241号会话持有一个TM锁，在执行insert into pzd2018语句在等待S锁
4468号会话持有一个TX锁，在执行insert into pz2018语句，在等待SX锁
通过与业务沟通与数据库查询发现了以下的锁表操作，并和业务确定了属于业务SQL
lock table pz2018 in exclusive mode
到这里问题已经清楚了，整个逻辑是这样的
241号会话将pz2018全表排他模式进行了锁定，导致4468会话无法对pz2018表进行insert操作，原因是无法在表上获取共享排它锁即SX锁，导致4468号会话进入等待模式
而4468号会话在等待前进行了insert into pzd2018操作，而241号会话在插入时存在唯一约束，导致241会话进行TX锁等待，等待4468号session数据提交或者回滚
这样一个环状等待就形成了即死锁
等待发生时会话的等待情况
SQL> select a.sample_time, 2 a.session_id, 3 a.session_serial#, 4 a.blocking_session bsession, 5 a.blocking_session_serial# bserial#, 6 a.event, 7 a.machine, 8 a.module, 9 a.sql_opname 10 from dba_hist_active_sess_history a 11 where a.session_id in (241, 4468, 6819, 10817) 12 and a.sample_time > to_date('2018070310', 'yyyymmddhh24') 13 and a.sample_time < to_date('2018070312', 'yyyymmddhh24') 14 and a.event is not null 15 order by a.sample_time 16 ; SAMPLE_TIME SESSION_ID SESSION_SERIAL# BSESSION BSERIAL# EVENT MACHINE MODULE SQL_OPNAME ------------------------------ ---------- --------------- ---------- ---------- ------------------------------ ------------------------------ ------------------------------ ---------------------------------------------------------------- 03-7月 -18 10.00.40.857 上午 241 425 6587 7875 enq: TM - contention WORKGROUPTL3050-WZ CWV4.2.8.337_20131204.exe LOCK TABLE 03-7月 -18 10.49.45.384 上午 10817 97 12929 7665 read by other session webserver JDBC Thin Client SELECT 03-7月 -18 10.51.16.143 上午 241 425 4468 2029 enq: TX - row lock contention WORKGROUPTL3050-WZ CWV4.2.8.337_20131204.exe INSERT 03-7月 -18 10.51.16.143 上午 4468 2029 241 425 enq: TM - contention ZDCWWANGH88208561 XCV5（新5.24）.exe INSERT 03-7月 -18 10.52.46.903 上午 10817 121 null event dbserver1 SELECT 03-7月 -18 10.53.57.464 上午 6819 99 10817 133 enq: TX - row lock contention ZDCWWANGWD88981612 CWV4.exe INSERT 03-7月 -18 10.53.57.464 上午 10817 133 6819 99 enq: TM - contention ZDCWWANGH88208561 XCV5（新5.24）.exe INSERT 03-7月 -18 10.54.07.554 上午 10817 133 db file parallel read ZDCWWANGH88208561 XCV5（新5.24）.exe INSERT 8 rows selected
3、锁等待的模拟，问题复现
---session1SQL> lock table pz2018 in exclusive mode;Table(s) Locked.----session2SQL> insert into pzd2018(OBJECT_ID,OBJECT_NAME) values(100000000,'PZD_Yong');1 row created.SQL> insert into pz2018(OBJECT_ID,OBJECT_NAME) values(100000000,'PZ_Yong');----session2执行直接hang住无法完成，在等待TM锁SQL> select s.SID,s.BLOCKING_SESSION bsid,s.EVENT,s.MACHINE,s.MODULE,s.STATUS,s.STATE from v
查看数据库alert日志发现
Thu Jul 05 11:40:40 2018 ORA-00060: Deadlock detected. More info in file /u01/app/oracle/diag/rdbms/dtstack1/dtstack1/trace/dtstack1_ora_29840.trc.
查看死锁trace
Deadlock graph: ---------Blocker(s)-------- ---------Waiter(s)--------- Resource Name process session holds waits process session holds waits TM-0001554c-00000000 28 17 X 27 143 SX TX-00040008-000002d9 27 143 X 28 17 S session 17: DID 0001-001C-00000024 session 143: DID 0001-001B-00000155 session 143: DID 0001-001B-00000155 session 17: DID 0001-001C-00000024 Rows waited on: Session 17: no row Session 143: obj - rowid = 0001554C - AAAAAAAAAAAAAAAAAA (dictionary objn - 87372, file - 0, block - 0, slot - 0) ----- Information for the OTHER waiting sessions ----- Session 143: sid: 143 ser: 905 audsid: 610017 user: 85/DTYONG flags: (0x45) USR/- flags_idl: (0x1) BSY/-/-/-/-/- flags2: (0x40009) -/-/INC pid: 27 O/S info: user: oracle, term: UNKNOWN, ospid: 29846 image: oracle@172-16-8-110 (TNS V1-V3) client details: O/S info: user: oracle, term: pts/1, ospid: 29845 machine: 172-16-8-110 program: sqlplus@172-16-8-110 (TNS V1-V3) application name: SQL*Plus, hash value=3669949024 current SQL: insert into pz2018(OBJECT_ID,OBJECT_NAME) values(100000000,'PZ_Yong') ----- End of information for the OTHER waiting sessions ----- Information for THIS session: ----- Current SQL Statement for this session (sql_id=7jbgf8fc4cac0) ----- insert into pzd2018(OBJECT_ID,OBJECT_NAME) values(100000000,'PZD_Yong') =================================================== PROCESS STATE ------------- Process global information: process: 0x914c4ed0, call: 0x910d2008, xact: 0x90390710, curses: 0x916aa020, usrses: 0x916aa020 in_exception_handler: no ---------------------------------------- SO: 0x914c4ed0, type: 2, owner: (nil), flag: INIT/-/-/0x00 if: 0x3 c: 0x3 proc=0x914c4ed0, name=process, file=ksu.h LINE:12721, pg=0 (process) Oracle pid:28, ser:23, calls cur/top: 0x910d2008/0x910d2008 flags : (0x0) - flags2: (0x0), flags3: (0x10) intr error: 0, call error: 0, sess error: 0, txn error 0 intr queue: empty ksudlp FALSE at location: 0 (post info) last post received: 138 0 2 last post received-location: ksl2.h LINE:2374 ID:kslpsr last process to post me: 0x914b3298 1 6 last post sent: 0 0 26 last post sent-location: ksa2.h LINE:285 ID:ksasnd last process posted by me: 0x914b3298 1 6 (latch info) wait_event=0 bits=0x0 Process Group: DEFAULT, pseudo proc: 0x915515e8 O/S info: user: oracle, term: UNKNOWN, ospid: 29840 OSD pid info: Unix process pid: 29840, image: oracle@172-16-8-110 (TNS V1-V3) ---------------------------------------- SO: 0x916aa020, type: 4, owner: 0x914c4ed0, flag: INIT/-/-/0x00 if: 0x3 c: 0x3 proc=0x914c4ed0, name=session, file=ksu.h LINE:12729, pg=0 (session) sid: 17 ser: 683 trans: 0x90390710, creator: 0x914c4ed0 flags: (0x45) USR/- flags_idl: (0x1) BSY/-/-/-/-/- flags2: (0x40009) -/-/INC
