Oracle进程：LMS 进程与Oracle RAC

LMS进程是Oracle RAC环境下非常重要的一个进程，关于这个进程的解释在不同文档中也有所不同。

在Oracle 9iR2的概念手册中这样介绍：

Lock Manager Server Process (LMS)

In Oracle9i Real Application Clusters, a Lock Manager Server process (LMS) provides inter-instance resource management.

也就是说LMS进程也就是 Lock Manager Server Process 的缩写，意思是 锁管理服务器进程。

LMS进程在RAC环境下可能会启动多个，其设置规则为：max( 2, #CPU/2) but no more than 10

而在Oracle 9iR2 RAC的概念文档中，Oracle这样解释LMS进程：

Global Cache Service Processes (LMSn)

The processes that handle remote Global Cache Service (GCS) messages. Real Application Clusters provides for up to 10 Global Cache Service Processes. The number of LMSn varies depending on the amount of messaging traffic amount the nodes in the cluster. The LMSn handle the acquisition interrupt and blocking interrupt requests from a remote instance for Global Cache Service resources. For cross-instance consistent read requests, LMSn creates a consistent read version of the block and sends it to the requesting instance. LMSn also controls the flow of messages to and from remote instances.

在这个文档中，Oracle将LMS重新定义为Global Cache Service Processes ，因为在9iRAC中，Oracle引入了大量Service的概念，所以LMS称为 Global Cache Service Processes 就更为合适一些，于是潜移默化的改变发生了，而且LMS的本意在新的定义中已经看不出来。

Oracle很多概念都经历了这样的变化，在变化中失去了原来的含义，如果不从源头上追溯，很多概念理解起来就会有很多困难。

看看在Oracle 10g中的定义：

Global Cache Service (LMS) - In a Real Application Clusters environment, this process manages resources and provides inter-instance resource control.

变化就是这样产生的。以下是一个Oracle 10g 10.2.0.4环境下的进程信息：[oracle@wapdbrac1 ~]$ ps -ef|grep lms

oracle 14712 3313 0 16:51 pts/1 00:00:00 grep lms

oracle 15882 1 0 May05 ? 00:00:01 asm_lms0_+ASM1

oracle 29839 1 0 May05 ? 00:12:07 ora_lms0_wapdb1

oracle 29843 1 0 May05 ? 00:13:39 ora_lms1_wapdb1

在LMS的进程跟踪文件中，你可以看到类似如下信息：/opt/oracle/admin/wapdb/bdump/wapdb1_lms1_7605.trc

Oracle Database 10g Enterprise Edition Release 10.2.0.3.0 - Production

With the Partitioning, Real Application Clusters, OLAP and Data Mining options

ORACLE_HOME = /opt/oracle/product/10.2.0/db

System name: Linux

Node name: wapdbrac1

Release: 2.6.9-55.0.0.0.2.ELhugemem

Version: #1 SMP Wed May 2 15:04:06 PDT 2007

Machine: i686

Instance name: wapdb1

Redo thread mounted by this instance: 0 Oracle process number: 8

Unix process pid: 7605, image: oracle@wapdbrac1 (LMS1)

*** SERVICE NAME:() 2008-02-22 19:10:54.020

*** SESSION ID:(1099.1) 2008-02-22 19:10:54.020

0 GCS shadows cancelled, 0 closed

0 GCS resources traversed, 0 cancelled

LMS 1: 126150 GCS resources on freelist, 126190 on array, 126190 allocated

0 GCS shadows traversed, 0 replayed, 0 duplicates

lms 1 finished replaying gcs resources

0 write requests issued in 4788 GCS resources

0 PIs marked suspect, 0 flush PI msgs

0 write requests issued in 4797 GCS resources

0 PIs marked suspect, 0 flush PI msgs

0 write requests issued in 4751 GCS resources

0 PIs marked suspect, 0 flush PI msgs

0 write requests issued in 4644 GCS resources

0 PIs marked suspect, 0 flush PI msgs

0 write requests issued in 439 GCS resources

0 PIs marked suspect, 0 flush PI msgs

lms 1 finished fixing gcs write protocol

*** 2008-03-17 14:54:10.828

KJM_HISTORY: RCVR STALL OP(12) context 0 elapsed 536578176 us

KJM HIST LMS1:

12:536578176 7:7 6:2 10:3 17:6 16:4 15:4 12:30675 7:6 6:3

10:3 17:7 16:3 15:5 12:30242 7:6 6:2 10:3 17:6 16:3

15:5 12:30241 7:5 6:3 10:3 17:7 16:3 15:5 12:30242 7:6

6:3 10:3 17:8 16:3 15:4 12:30245 7:5 6:3 10:2 17:7

16:4 15:4 12:30240 7:7 6:2 10:3 17:7 16:4 15:4 12:30243

7:6 6:2 10:2 17:7 16:4 15:5 12:30260 7:5 6:2 10:3

17:5 16:3 15:3 12:30243

----------------------------------------

SO: 0x7a17d5f0, type: 4, owner: 0x7ca38d14, flag: INIT/-/-/0x00

(session) sid: 1099 trans: (nil), creator: 0x7ca38d14, flag: (51) USR/- BSY/-/-/-/-/-

DID: 0000-0000-00000000, short-term DID: 0000-0000-00000000

txn branch: (nil)

oct: 0, prv: 0, sql: (nil), psql: (nil), user: 0/SYS

last wait for 'gcs remote message' blocking sess=0x(nil) seq=12843 wait_time=536578162 seconds since wait started=611

waittime=18, poll=0, event=0

Dumping Session Wait History

for 'gcs remote message' count=1 wait_time=536578162

waittime=18, poll=0, event=0

for 'gcs remote message' count=1 wait_time=30661

waittime=18, poll=0, event=0

for 'gcs remote message' count=1 wait_time=30228

waittime=18, poll=0, event=0

for 'gcs remote message' count=1 wait_time=30227

waittime=18, poll=0, event=0

for 'gcs remote message' count=1 wait_time=30226

waittime=18, poll=0, event=0

for 'gcs remote message' count=1 wait_time=30229

waittime=18, poll=0, event=0

for 'gcs remote message' count=1 wait_time=30225

waittime=18, poll=0, event=0

for 'gcs remote message' count=1 wait_time=30226

waittime=18, poll=0, event=0

for 'gcs remote message' count=1 wait_time=30244

waittime=18, poll=0, event=0

for 'gcs remote message' count=1 wait_time=30232

waittime=18, poll=0, event=0

temporary object counter: 0

----------------------------------------

UOL used : 0 locks(used=0, free=0)

KGX Atomic Operation Log 0x7bb78228

Mutex (nil)(0, 0) idn 0 oper NONE

Library Cache uid 1099 efd 0 whr 0 slp 0

KGX Atomic Operation Log 0x7bb78250

Mutex (nil)(0, 0) idn 0 oper NONE

Library Cache uid 1099 efd 0 whr 0 slp 0

KGX Atomic Operation Log 0x7bb78278

Mutex (nil)(0, 0) idn 0 oper NONE

Library Cache uid 1099 efd 0 whr 0 slp 0

SKGXPIWAIT: keepalive_reset elapsed 791166 ts 2058197925 last ping 2057406759 check 600000

PING HISTORY for CONTEXT Time Stampe 0x7aad9ba5

MSGs Time Stamp

--- ----------

1 0x7aa18927

1 0x7a5cdef7

1 0x7a6172df

1 0x7a6606bc

1 0x7a6a9a9b

1 0x7a6f2e7a

1 0x7a73c258

1 0x7a785637

1 0x7a7cea20

1 0x7a817e08

1 0x7a8611e7

1 0x7a8aa5c5

1 0x7a8f39a4

1 0x7a93cd83

1 0x7a986161

1 0x7a9cf542

SKGXP_KEEPALIVE_RESET: alarm unblocked already

SKGXP_KEEPALIVE_RESET: restting shared signal for keep alive messages

SKGXP_KEEPALIVE_RESET: re-initing shared signal for keep alive messages

SKGXP_KEEPALIVE_RESET: setting alarm for keep alive messages

*** 2008-04-24 15:26:59.079

0 GCS shadows cancelled, 0 closed

14477 GCS resources traversed, 0 cancelled

LMS 1: 97446 GCS resources on freelist, 126190 on array, 126190 allocated

30592 GCS shadows traversed, 0 replayed, 0 duplicates

lms 1 finished replaying gcs resources

0 write requests issued in 7498 GCS resources

0 PIs marked suspect, 0 flush PI msgs

0 write requests issued in 7456 GCS resources

0 PIs marked suspect, 0 flush PI msgs

0 write requests issued in 7484 GCS resources

0 PIs marked suspect, 0 flush PI msgs

0 write requests issued in 7468 GCS resources

0 PIs marked suspect, 0 flush PI msgs

0 write requests issued in 686 GCS resources

0 PIs marked suspect, 0 flush PI msgs

lms 1 finished fixing gcs write protocol

-The End-

By eygle on 2008-06-04 16:50 |

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