Oracle 死锁分析过程详解

Oracle 死锁分析

关于死锁一般3种处理方式

1、事前预测

2、资源分级

3、事后检测释放

我知道的ORACLE MYSQL都是采用第三种在行锁级别上的话。

这里分析一个ORACLE死锁，首先一个死锁肯定会生成一个TRACE文件，这里会记录很多信息如：

Deadlock graph:

---------Blocker(s)--------  ---------Waiter(s)---------

Resource Name          process session holds waits  process session holds waits

TX-0058000f-0000b473      649    1204    X            651    1252          X

TX-0019001c-0004e0b0      651    1252    X            649    1204          X

这里给出了进程和会话id

Rows waited on:

Session 1204: obj - rowid = 0003D942 - AAA9lCAAEAADgaNAAI

(dictionary objn - 252226, file - 4, block - 919181, slot - 8)

Session 1252: obj - rowid = 0003D942 - AAA9lCAAEAADgaNAAa

(dictionary objn - 252226, file - 4, block - 919181, slot - 26)

这里给出导致死锁的行

同时给出了最后触发死锁会话 1252的语句

----- Information for the OTHER waiting sessions -----

Session 1252:

sid: 1252 ser: 35883 audsid: 7170593 user: 235/FEECORESV

flags: (0x100045) USR/- flags_idl: (0x1) BSY/-/-/-/-/-

flags2: (0x40009) -/-/INC

pid: 651 O/S info: user: oracle, term: UNKNOWN, ospid: 13035

image: oracle@oratest11

client details:

O/S info: user: sky, term: unknown, ospid: 1234

machine: autobots program: JDBC Thin Client

application name: JDBC Thin Client, hash value=2546894660

current SQL:

UPDATE *******

----- End of information for the OTHER waiting sessions -----

Information for THIS session:

----- Current SQL Statement for this session (sql_id=3vh5sc7pgtrjy) -----

UPDATE *******

那么到这里我们大概能够分析出

A:1204拿到AAA9lCAAEAADgaNAAa 行锁    B:1252 拿到 AAA9lCAAEAADgaNAAI 行锁

C:1204需要AAA9lCAAEAADgaNAAI 则等待  D:1252 需要  AAA9lCAAEAADgaNAAa 则触发死锁1204回滚

那么随后trace给出1204 C这一步等待时间和事物信息

SO: 0xee1fcd10, type: 4, owner: 0xf031e750, flag: INIT/-/-/0x00 if: 0x3 c: 0x3

proc=0xf031e750, name=session, file=ksu.h LINE:12624, pg=0

(session) sid: 1204 ser: 2443 trans: 0xe9221180, creator: 0xf031e750

flags: (0x100045) USR/- flags_idl: (0x1) BSY/-/-/-/-/-

flags2: (0x40009) -/-/INC

DID: , short-term DID:

txn branch: (nil)

oct: 6, prv: 0, sql: 0xf25d2278, psql: 0xc4346788, user: 235/FEECORESV

ksuxds FALSE at location: 0

service name: SYS$USERS

Current Wait Stack:

0: waiting for 'enq: TX - row lock contention'

name|mode=0x54580006, usn<<16 | slot=0x19001c, sequence=0x4e0b0

wait_id=33 seq_num=34 snap_id=1

wait times: snap=3.001739 sec, exc=3.001739 sec, total=3.001739 sec

wait times: max=infinite, heur=3.001739 sec

wait counts: calls=1 os=1

in_wait=1 iflags=0x15a0

随后给出了导致他等待会话的等待信息，这里不给出。当然随后还有很多类容，但是关键就是如上

但是这里并没有一个显示的事物执行的过程，如果要看到完整的语句我们需要日志挖掘，我挖掘出来的如下：

1204：

set transaction read write;

select * from TEST.TEST where ROWID = 'AAA9lCAAEAADgaNAAa' for update;

commit;

1252：

set transaction read write;

select * from TEST.TEST where ROWID = 'AAA9lCAAEAADgaNAAI' for update;

update TEST.TEST set "STATUS" = 'SUCCESS', "DETAIL" = '执行成功', "RAW_UPDATE_TIME" = TO_TIMESTAMP('19-SEP-16 01.27.25.714715 PM') where "IDENTITY" = '39319' and "STATUS" = 'PROCESSING' and "DETAIL" IS NULL and "RAW_UPDATE_TIME" = TO_TIMESTAMP('19-SEP-16 01.27.24.611036 PM') and ROWID = 'AAA9lCAAEAADgaNAAa';

commit;

这样能够清楚的看到1204的update并没有执行，而由于触发了deadlock回滚掉了