1. 대기 이벤트(Wait Event)란?

대기 이벤트란 오라클 인스턴스 내에서 공유된 자원을 사용하기 위해 프로세스들이 점유를 해야 하는데 이 때 점유를 하지 못한 상태에서는 Sleep 상태에 빠지며
이 때 발생되는 현상을 대기 이벤트(Wait Event)라고 함.
대기 이벤트는 오라클 개발자들이 Debuging 용도로 개발한 것인데 오늘날까지 발전되어 성능관리 분야에 일대 혁신을 가져옴.
대기 이벤트 종류(10.2.0.3 기준)
- 대기 이벤트 종류는 아래의 SQL을 수행하여 확인할 수 있다.


SELECT WAIT_CLASS,
       NAME,
       PARAMETER1,
       PARAMETER2,
       PARAMETER3
FROM   V$EVENT_NAME
ORDER BY WAIT_CLASS,
         NAME
;

Count	WAIT_CLASS	NAME	PARAMETER1	PARAMETER2	PARAMETER3
1	Administrative	ASM COD rollback operation completion	dismount force
2	Administrative	ASM mount : wait for heartbeat
3	Administrative	Backup: sbtbackup
4	Administrative	Backup: sbtclose
5	Administrative	Backup: sbtclose2
6	Administrative	Backup: sbtcommand
7	Administrative	Backup: sbtend
8	Administrative	Backup: sbterror
9	Administrative	Backup: sbtinfo
10	Administrative	Backup: sbtinfo2
11	Administrative	Backup: sbtinit
12	Administrative	Backup: sbtinit2
13	Administrative	Backup: sbtopen
14	Administrative	Backup: sbtpcbackup
15	Administrative	Backup: sbtpccancel
16	Administrative	Backup: sbtpccommit
17	Administrative	Backup: sbtpcend
18	Administrative	Backup: sbtpcquerybackup
19	Administrative	Backup: sbtpcqueryrestore
20	Administrative	Backup: sbtpcrestore
21	Administrative	Backup: sbtpcstart
22	Administrative	Backup: sbtpcstatus
23	Administrative	Backup: sbtpcvalidate
24	Administrative	Backup: sbtread
25	Administrative	Backup: sbtread2
26	Administrative	Backup: sbtremove
27	Administrative	Backup: sbtremove2
28	Administrative	Backup: sbtrestore
29	Administrative	Backup: sbtwrite
30	Administrative	Backup: sbtwrite2
31	Administrative	JS coord start wait
32	Administrative	JS kgl get object wait
33	Administrative	JS kill job wait
34	Administrative	alter rbs offline
35	Administrative	alter system set dispatcher	waited
36	Administrative	buffer pool resize	buffer pool id	current size	new size
37	Administrative	enq: DB - contention	name_mode	EnqMode	0
38	Administrative	enq: TW - contention	name_mode	0	operation
39	Administrative	enq: ZG - contention	name_mode	file group id	version id
40	Administrative	index (re)build online cleanup	object	mode	wait
41	Administrative	index (re)build online merge	object	mode	wait
42	Administrative	index (re)build online start	object	mode	wait
43	Administrative	multiple dbwriter suspend/resume for file offline
44	Administrative	switch logfile command
45	Administrative	switch undo - offline
46	Administrative	wait for possible quiesce finish
47	Application	SQL*Net break/reset to client	driver id	break?
48	Application	SQL*Net break/reset to dblink	driver id	break?
49	Application	Streams capture: filter callback waiting for ruleset
50	Application	Streams: apply reader waiting for DDL to apply	sleep time
51	Application	Wait for Table Lock
52	Application	enq: KO - fast object checkpoint	name_mode	2	0
53	Application	enq: PW - flush prewarm buffers	name_mode	0	0
54	Application	enq: RO - contention	name_mode	2	0
55	Application	enq: RO - fast object reuse	name_mode	2	0
56	Application	enq: TM - contention	name_mode	object #	table/partition
57	Application	enq: TX - row lock contention	name_mode	usn<<16 _ slot	sequence
58	Application	enq: UL - contention	name_mode	id	0
59	Cluster	ASM PST query : wait for PM grp 0 grant
60	Cluster	Streams: RAC waiting for inter instance ack
61	Cluster	gc assume	le
62	Cluster	gc block recovery request	file#	block#	class#
63	Cluster	gc buffer busy	file#	block#	id#
64	Cluster	gc claim
65	Cluster	gc cr block 2-way
66	Cluster	gc cr block 3-way
67	Cluster	gc cr block busy
68	Cluster	gc cr block congested
69	Cluster	gc cr block lost
70	Cluster	gc cr block unknown
71	Cluster	gc cr cancel	le
72	Cluster	gc cr disk read
73	Cluster	gc cr disk request	file#	block#	class#
74	Cluster	gc cr failure
75	Cluster	gc cr grant 2-way
76	Cluster	gc cr grant busy
77	Cluster	gc cr grant congested
78	Cluster	gc cr grant unknown
79	Cluster	gc cr multi block request	file#	block#	class#
80	Cluster	gc cr request	file#	block#	class#
81	Cluster	gc current block 2-way
82	Cluster	gc current block 3-way
83	Cluster	gc current block busy
84	Cluster	gc current block congested
85	Cluster	gc current block lost
86	Cluster	gc current block unknown
87	Cluster	gc current cancel	le
88	Cluster	gc current grant 2-way
89	Cluster	gc current grant busy
90	Cluster	gc current grant congested
91	Cluster	gc current grant unknown
92	Cluster	gc current multi block request	file#	block#	id#
93	Cluster	gc current request	file#	block#	id#
94	Cluster	gc current retry
95	Cluster	gc current split
96	Cluster	gc domain validation	file#	block#	class#
97	Cluster	gc freelist
98	Cluster	gc prepare
99	Cluster	gc quiesce wait
100	Cluster	gc recovery free
101	Cluster	gc recovery quiesce
102	Cluster	gc remaster	file#	block#	class#
103	Cluster	lock remastering
104	Cluster	pi renounce write complete	file#	block#
105	Cluster	retry contact SCN lock master
106	Commit	log file sync	buffer#
107	Concurrency	buffer busy waits	file#	block#	class#
108	Concurrency	cursor: mutex S	idn	value	where_sleeps
109	Concurrency	cursor: mutex X	idn	value	where_sleeps
110	Concurrency	cursor: pin S wait on X	idn	value	where_sleeps
111	Concurrency	enq: TX - index contention	name_mode	usn<<16 _ slot	sequence
112	Concurrency	latch: In memory undo latch	address	number	tries
113	Concurrency	latch: MQL Tracking Latch	address	number	tries
114	Concurrency	latch: Undo Hint Latch	address	number	tries
115	Concurrency	latch: cache buffers chains	address	number	tries
116	Concurrency	latch: library cache	address	number	tries
117	Concurrency	latch: library cache lock	address	number	tries
118	Concurrency	latch: library cache pin	address	number	tries
119	Concurrency	latch: row cache objects	address	number	tries
120	Concurrency	latch: shared pool	address	number	tries
121	Concurrency	library cache load lock	object address	lock address	100*mask+namespace
122	Concurrency	library cache lock	handle address	lock address	100*mode+namespace
123	Concurrency	library cache pin	handle address	pin address	100*mode+namespace
124	Concurrency	logout restrictor
125	Concurrency	os thread startup
126	Concurrency	pipe put	handle address	record length	timeout
127	Concurrency	resmgr:internal state change	location
128	Concurrency	resmgr:internal state cleanup	location
129	Concurrency	resmgr:sessions to exit	location
130	Concurrency	row cache lock	cache id	mode	request
131	Concurrency	row cache read	cache id	address	times
132	Configuration	Streams AQ: enqueue blocked on low memory
133	Configuration	Streams capture: resolve low memory condition
134	Configuration	Streams capture: waiting for subscribers to catch up
135	Configuration	checkpoint completed
136	Configuration	enq: HW - contention	name_mode	table space #	block
137	Configuration	enq: SQ - contention	name_mode	object #	0
138	Configuration	enq: SS - contention	name_mode	tablespace #	dba
139	Configuration	enq: ST - contention	name_mode	0	0
140	Configuration	enq: TX - allocate ITL entry	name_mode	usn<<16 _ slot	sequence
141	Configuration	free buffer waits	file#	block#	set-id#
142	Configuration	latch: redo copy	address	number	tries
143	Configuration	latch: redo writing	address	number	tries
144	Configuration	log buffer space
145	Configuration	log file switch (archiving needed)
146	Configuration	log file switch (checkpoint incomplete)
147	Configuration	log file switch (private strand flush incomplete)
148	Configuration	log file switch completion
149	Configuration	sort segment request
150	Configuration	statement suspended, wait error to be cleared
151	Configuration	undo segment extension	segment#
152	Configuration	undo segment tx slot	segment#
153	Configuration	wait for EMON to process ntfns
154	Configuration	write complete waits	file#	block#
155	Idle	ASM background timer
156	Idle	DIAG idle wait	component	where	wait time(millisec)
157	Idle	EMON idle wait
158	Idle	HS message to agent
159	Idle	JS external job
160	Idle	KSV master wait
161	Idle	LNS ASYNC archive log
162	Idle	LNS ASYNC dest activation
163	Idle	LNS ASYNC end of log
164	Idle	LogMiner: client waiting for transaction
165	Idle	LogMiner: slave waiting for activate message
166	Idle	LogMiner: wakeup event for builder
167	Idle	LogMiner: wakeup event for preparer
168	Idle	LogMiner: wakeup event for reader
169	Idle	PL/SQL lock timer	duration
170	Idle	PX Deq Credit: need buffer	sleeptime/senderid	passes	qref
171	Idle	PX Deq: Execute Reply	sleeptime/senderid	passes
172	Idle	PX Deq: Execution Msg	sleeptime/senderid	passes
173	Idle	PX Deq: Index Merge Close	sleeptime/senderid	passes
174	Idle	PX Deq: Index Merge Execute	sleeptime/senderid	passes
175	Idle	PX Deq: Index Merge Reply	sleeptime/senderid	passes
176	Idle	PX Deq: Join ACK	sleeptime/senderid	passes
177	Idle	PX Deq: Msg Fragment	sleeptime/senderid	passes
178	Idle	PX Deq: Par Recov Change Vector	sleeptime/senderid	passes
179	Idle	PX Deq: Par Recov Execute	sleeptime/senderid	passes
180	Idle	PX Deq: Par Recov Reply	sleeptime/senderid	passes
181	Idle	PX Deq: Parse Reply	sleeptime/senderid	passes
182	Idle	PX Deq: Table Q Normal	sleeptime/senderid	passes
183	Idle	PX Deq: Table Q Sample	sleeptime/senderid	passes
184	Idle	PX Deq: Txn Recovery Reply	sleeptime/senderid	passes
185	Idle	PX Deq: Txn Recovery Start	sleeptime/senderid	passes
186	Idle	PX Deq: kdcph_mai	kdcph_mai
187	Idle	PX Deq: kdcphc_ack	kdcphc_ack
188	Idle	PX Deque wait	sleeptime/senderid	passes
189	Idle	PX Idle Wait	sleeptime/senderid	passes
190	Idle	SGA: MMAN sleep for component shrink	component id	current size	target size
191	Idle	SQL*Net message from client	driver id	#bytes
192	Idle	SQL*Net message from dblink	driver id	#bytes
193	Idle	Streams AQ: RAC qmn coordinator idle wait
194	Idle	Streams AQ: deallocate messages from Streams Pool
195	Idle	Streams AQ: delete acknowledged messages
196	Idle	Streams AQ: qmn coordinator idle wait
197	Idle	Streams AQ: qmn slave idle wait
198	Idle	Streams AQ: waiting for messages in the queue	queue id	process#	wait time
199	Idle	Streams AQ: waiting for time management or cleanup tasks
200	Idle	Streams fetch slave: waiting for txns
201	Idle	class slave wait	slave id
202	Idle	dispatcher timer	sleep time
203	Idle	gcs remote message	waittime	poll	event
204	Idle	ges remote message	waittime	loop	p3
205	Idle	i/o slave wait	msg ptr
206	Idle	jobq slave wait
207	Idle	parallel recovery coordinator waits for cleanup of slaves
208	Idle	pipe get	handle address	buffer length	timeout
209	Idle	pmon timer	duration
210	Idle	rdbms ipc message	timeout
211	Idle	single-task message
212	Idle	smon timer	sleep time	failed
213	Idle	virtual circuit status	circuit#	status
214	Idle	wait for unread message on broadcast channel	channel context	channel handle
215	Idle	wait for unread message on multiple broadcast channels	channel context	channel handle count
216	Idle	watchdog main loop
217	Network	ARCH wait for flow-control
218	Network	ARCH wait for net re-connect
219	Network	ARCH wait for netserver detach
220	Network	ARCH wait for netserver init 1
221	Network	ARCH wait for netserver init 2
222	Network	ARCH wait for netserver start
223	Network	ARCH wait on ATTACH
224	Network	ARCH wait on DETACH
225	Network	ARCH wait on SENDREQ
226	Network	LGWR wait on ATTACH
227	Network	LGWR wait on DETACH
228	Network	LGWR wait on LNS
229	Network	LGWR wait on SENDREQ
230	Network	LNS wait on ATTACH
231	Network	LNS wait on DETACH
232	Network	LNS wait on LGWR
233	Network	LNS wait on SENDREQ
234	Network	SQL*Net message to client	driver id	#bytes
235	Network	SQL*Net message to dblink	driver id	#bytes
236	Network	SQL*Net more data from client	driver id	#bytes
237	Network	SQL*Net more data from dblink	driver id	#bytes
238	Network	SQL*Net more data to client	driver id	#bytes
239	Network	SQL*Net more data to dblink	driver id	#bytes
240	Network	TCP Socket (KGAS)
241	Network	TEXT: URL_DATASTORE network wait
242	Network	dedicated server timer	wait event
243	Network	dispatcher listen timer	sleep time
244	Other	ARCH wait for archivelog lock
245	Other	ARCH wait for process death 1
246	Other	ARCH wait for process death 2
247	Other	ARCH wait for process death 3
248	Other	ARCH wait for process death 4
249	Other	ARCH wait for process death 5
250	Other	ARCH wait for process start 1
251	Other	ARCH wait for process start 2
252	Other	ARCH wait for process start 3
253	Other	ARCH wait for process start 4
254	Other	ARCH wait on c/f tx acquire 1
255	Other	ARCH wait on c/f tx acquire 2
256	Other	ASM background running
257	Other	ASM background starting
258	Other	ASM db client exists
259	Other	ASM internal hang test	test #
260	Other	AWR Flush
261	Other	AWR Metric Capture
262	Other	BFILE check if exists
263	Other	BFILE check if open
264	Other	BFILE closure
265	Other	BFILE get length
266	Other	BFILE get name object
267	Other	BFILE get path object
268	Other	BFILE internal seek
269	Other	BFILE open
270	Other	CGS skgxn join retry	retry count
271	Other	CGS wait for IPC msg
272	Other	Cluster Suspension wait
273	Other	Cluster stablization wait
274	Other	DBFG waiting for reply
275	Other	DBMS_LDAP: LDAP operation
276	Other	DFS db file lock	file#
277	Other	DFS lock handle	type_mode	id1	id2
278	Other	Data Guard broker: single instance	Data Guard broker: single instance
279	Other	Data Guard broker: wait upon ORA-12850 error	waiting for retrying the query to mask ORA-12850 error
280	Other	Data Guard: process clean up
281	Other	Data Guard: process exit
282	Other	FAL archive wait 1 sec for REOPEN minimum
283	Other	GCS lock cancel	le
284	Other	GCS lock cvt S	group	obj#	block#
285	Other	GCS lock cvt X	group	obj#	block#
286	Other	GCS lock esc	group	obj#	block#
287	Other	GCS lock esc X	group	obj#	block#
288	Other	GCS lock open	group	obj#	block#
289	Other	GCS lock open S	group	obj#	block#
290	Other	GCS lock open X	group	obj#	block#
291	Other	GCS recovery lock convert	group	obj#	block#
292	Other	GCS recovery lock open	group	obj#	block#
293	Other	GV$: slave acquisition retry wait time
294	Other	IPC busy async request
295	Other	IPC send completion sync	send count
296	Other	IPC wait for name service busy
297	Other	IPC waiting for OSD resources
298	Other	KJC: Wait for msg sends to complete	msg	dest_rcvr	mtype
299	Other	Kupp process shutdown	nalive	sleeptime	loop
300	Other	L1 validation	seghdr	l1bmb
301	Other	LGWR simulation latency wait
302	Other	LGWR wait for redo copy	copy latch #
303	Other	LGWR wait on full LNS buffer
304	Other	LGWR-LNS wait on channel
305	Other	LMON global data update
306	Other	LNS simulation latency wait
307	Other	LNS wait for LGWR redo
308	Other	Logical Standby Apply shutdown
309	Other	Logical Standby Terminal Apply	stage
310	Other	Logical Standby dictionary build
311	Other	Logical Standby pin transaction	xidusn	xidslt	xidsqn
312	Other	MMON (Lite) shutdown	process#	waited
313	Other	MMON slave messages
314	Other	MRP wait on archivelog archival
315	Other	MRP wait on archivelog arrival
316	Other	MRP wait on archivelog delay
317	Other	MRP wait on process death
318	Other	MRP wait on process restart
319	Other	MRP wait on process start
320	Other	MRP wait on startup clear
321	Other	MRP wait on state change
322	Other	MRP wait on state n_a
323	Other	MRP wait on state reset
324	Other	OLAP Aggregate Client Deq	sleeptime/senderid	passes
325	Other	OLAP Aggregate Client Enq	sleeptime/senderid	passes
326	Other	OLAP Aggregate Master Deq	sleeptime/senderid	passes
327	Other	OLAP Aggregate Master Enq	sleeptime/senderid	passes
328	Other	OLAP Null PQ Reason	sleeptime/senderid	passes
329	Other	OLAP Parallel Temp Grew	sleeptime/senderid	passes
330	Other	OLAP Parallel Temp Grow Request	sleeptime/senderid	passes
331	Other	OLAP Parallel Temp Grow Wait	sleeptime/senderid	passes
332	Other	OLAP Parallel Type Deq	sleeptime/senderid	passes
333	Other	PMON to cleanup pseudo-branches at svc stop time
334	Other	PX Deq Credit: free buffer	sleeptime/senderid	passes	qref
335	Other	PX Deq Credit: send blkd	sleeptime/senderid	passes	qref
336	Other	PX Deq: OLAP Update Close	sleeptime/senderid	passes
337	Other	PX Deq: OLAP Update Execute	sleeptime/senderid	passes
338	Other	PX Deq: OLAP Update Reply	sleeptime/senderid	passes
339	Other	PX Deq: Signal ACK	sleeptime/senderid	passes
340	Other	PX Deq: Table Q Close	sleeptime/senderid	passes
341	Other	PX Deq: Table Q Get Keys	sleeptime/senderid	passes
342	Other	PX Deq: Table Q qref	sleeptime/senderid	passes
343	Other	PX Deq: Test for msg	sleeptime/senderid	passes
344	Other	PX Deq: reap credit
345	Other	PX Nsq: PQ descriptor query
346	Other	PX Nsq: PQ load info query
347	Other	PX Send Wait
348	Other	PX create server	nservers	sleeptime	enqueue
349	Other	PX qref latch	function	sleeptime	qref
350	Other	PX server shutdown	nalive	sleeptime	loop
351	Other	PX signal server	serial	error	nbusy
352	Other	PX slave connection
353	Other	PX slave release
354	Other	RF - FSFO Wait for Ack
355	Other	RFS announce
356	Other	RFS attach
357	Other	RFS close
358	Other	RFS create
359	Other	RFS detach
360	Other	RFS dispatch
361	Other	RFS ping
362	Other	RFS register
363	Other	RVWR wait for flashback copy	copy latch #
364	Other	Replication Dequeue	sleeptime/senderid	passes
365	Other	SGA: allocation forcing component growth
366	Other	SGA: sga_target resize
367	Other	Streams AQ: enqueue blocked due to flow control
368	Other	Streams AQ: qmn coordinator waiting for slave to start
369	Other	Streams AQ: waiting for busy instance for instance_name	where	wait_count
370	Other	Streams capture: waiting for archive log
371	Other	Streams capture: waiting for database startup
372	Other	Sync ASM rebalance
373	Other	Wait for TT enqueue	tsn
374	Other	Wait for shrink lock	object_id	lock_mode
375	Other	Wait for shrink lock2	object_id	lock_mode
376	Other	Wait on stby instance close
377	Other	affinity expansion in replay
378	Other	block change tracking buffer space
379	Other	buffer busy	group#	obj#	block#
380	Other	buffer deadlock	dba	class*10+mode	flag
381	Other	buffer dirty disabled	group#
382	Other	buffer exterminate	file#	block#	buf_ptr
383	Other	buffer freelistbusy	group#	obj#	block#
384	Other	buffer invalidation wait	group#	obj#	block#
385	Other	buffer latch	latch addr	chain#
386	Other	buffer rememberlist busy	group#	obj#	block#
387	Other	buffer resize
388	Other	buffer write wait	group#	obj#	block#
389	Other	buffer writeList full	group#	obj#	block#
390	Other	change tracking file parallel write	blocks	requests
391	Other	change tracking file synchronous read	block#	blocks
392	Other	change tracking file synchronous write	block#	blocks
393	Other	check CPU wait times
394	Other	checkpoint advanced	group#
395	Other	cleanup of aborted process	location
396	Other	control file diagnostic dump	type	param
397	Other	control file heartbeat
398	Other	cr request retry	file#	block#
399	Other	cursor: pin S	idn	value	where_sleeps
400	Other	cursor: pin X	idn	value	where_sleeps
401	Other	debugger command
402	Other	dispatcher shutdown	waited
403	Other	dma prepare busy	group	obj#	block#
404	Other	dupl. cluster key	dba
405	Other	enq: AD - allocate AU	name_mode	group and disk number	AU number
406	Other	enq: AD - deallocate AU	name_mode	group and disk number	AU number
407	Other	enq: AF - task serialization	name_mode	task id	0
408	Other	enq: AG - contention	name_mode	workspace #	generation
409	Other	enq: AM - client registration	name_mode	id1	id2
410	Other	enq: AM - rollback COD reservation	name_mode	id1	id2
411	Other	enq: AM - shutdown	name_mode	id1	id2
412	Other	enq: AO - contention	name_mode	workspace #	object #
413	Other	enq: AS - modify service	name_mode	0	0
414	Other	enq: AS - service activation	name_mode	0	0
415	Other	enq: AT - contention	name_mode	0	0
416	Other	enq: AU - audit index file	name_mode	XML audit index file	0
417	Other	enq: AW - AW generation lock	name_mode	operation	workspace #
418	Other	enq: AW - AW state lock	name_mode	operation	workspace #
419	Other	enq: AW - AW$ table lock	name_mode	operation	workspace #
420	Other	enq: AW - user access for AW	name_mode	operation	workspace #
421	Other	enq: BF - allocation contention	name_mode	node#/parallelizer#	bloom#
422	Other	enq: BR - file shrink	name_mode	operation	file #
423	Other	enq: BR - proxy-copy	name_mode	operation	file #
424	Other	enq: CF - contention	name_mode	0	operation
425	Other	enq: CI - contention	name_mode	opcode	type
426	Other	enq: CL - compare labels	name_mode	object #	0
427	Other	enq: CL - drop label	name_mode	object #	0
428	Other	enq: CM - gate	name_mode	disk group #	type
429	Other	enq: CM - instance	name_mode	disk group #	type
430	Other	enq: CN - race with init	name_mode	reg id	0
431	Other	enq: CN - race with reg	name_mode	reg id	0
432	Other	enq: CN - race with txn	name_mode	reg id	0
433	Other	enq: CT - CTWR process start/stop	name_mode	operation	operation parm
434	Other	enq: CT - change stream ownership	name_mode	operation	operation parm
435	Other	enq: CT - global space management	name_mode	operation	operation parm
436	Other	enq: CT - local space management	name_mode	operation	operation parm
437	Other	enq: CT - reading	name_mode	operation	operation parm
438	Other	enq: CT - state	name_mode	operation	operation parm
439	Other	enq: CT - state change gate 1	name_mode	operation	operation parm
440	Other	enq: CT - state change gate 2	name_mode	operation	operation parm
441	Other	enq: CU - contention	name_mode	handle	handle
442	Other	enq: DD - contention	name_mode	disk group	type
443	Other	enq: DF - contention	name_mode	0	file #
444	Other	enq: DG - contention	name_mode	disk group	type
445	Other	enq: DL - contention	name_mode	object #	0
446	Other	enq: DM - contention	name_mode	type	type
447	Other	enq: DN - contention	name_mode	0	0
448	Other	enq: DP - contention	name_mode	0	0
449	Other	enq: DR - contention	name_mode	0	0
450	Other	enq: DS - contention	name_mode	0	0
451	Other	enq: DT - contention	name_mode	0	0
452	Other	enq: DV - contention	name_mode	object #	0
453	Other	enq: DX - contention	name_mode	transaction entry #	0
454	Other	enq: FA - access file	name_mode	disk group number	file number
455	Other	enq: FB - contention	name_mode	tablespace #	dba
456	Other	enq: FC - open an ACD thread	name_mode	disk group	thread
457	Other	enq: FC - recover an ACD thread	name_mode	disk group	thread
458	Other	enq: FD - Flashback coordinator	name_mode	Internal	Internal
459	Other	enq: FD - Flashback on/off	name_mode	Internal	Internal
460	Other	enq: FD - Marker generation	name_mode	Internal	Internal
461	Other	enq: FD - Restore point create/drop	name_mode	Internal	Internal
462	Other	enq: FD - Tablespace flashback on/off	name_mode	Internal	Internal
463	Other	enq: FG - FG redo generation enq race	name_mode	disk group	type
464	Other	enq: FG - LGWR redo generation enq race	name_mode	disk group	type
465	Other	enq: FG - serialize ACD relocate	name_mode	disk group	type
466	Other	enq: FL - Flashback database log	name_mode	Log #	zero
467	Other	enq: FL - Flashback db command	name_mode	Log #	zero
468	Other	enq: FM - contention	name_mode	0	0
469	Other	enq: FP - global fob contention	name_mode	low file obj add	high file obj add
470	Other	enq: FR - contention	name_mode	disk group	unused
471	Other	enq: FS - contention	name_mode	0	type
472	Other	enq: FT - allow LGWR writes	name_mode	disk group	thread
473	Other	enq: FT - disable LGWR writes	name_mode	disk group	thread
474	Other	enq: FU - contention	name_mode	0	0
475	Other	enq: HD - contention	name_mode	disk group	0
476	Other	enq: HP - contention	name_mode	tablespace #	dba
477	Other	enq: HQ - contention	name_mode	object #	hash value
478	Other	enq: HV - contention	name_mode	object #	0
479	Other	enq: IA - contention	name_mode	0	0
480	Other	enq: ID - contention	name_mode	0	0
481	Other	enq: IL - contention	name_mode	object #	0
482	Other	enq: IM - contention for blr	name_mode	pool #	0
483	Other	enq: IR - contention	name_mode	0	0/1
484	Other	enq: IR - contention2	name_mode	0	0/1
485	Other	enq: IS - contention	name_mode	0	type
486	Other	enq: IT - contention	name_mode	object #	0
487	Other	enq: JD - contention	name_mode	0	0
488	Other	enq: JI - contention	name_mode	view object #	0
489	Other	enq: JQ - contention	name_mode	0	0
490	Other	enq: JS - contention	name_mode	service ID	queue type
491	Other	enq: JS - evt notify	name_mode	service ID	queue type
492	Other	enq: JS - evtsub add	name_mode	service ID	queue type
493	Other	enq: JS - evtsub drop	name_mode	service ID	queue type
494	Other	enq: JS - job recov lock	name_mode	service ID	queue type
495	Other	enq: JS - job run lock - synchronize	name_mode	service ID	queue type
496	Other	enq: JS - q mem clnup lck	name_mode	service ID	queue type
497	Other	enq: JS - queue lock	name_mode	service ID	queue type
498	Other	enq: JS - sch locl enqs	name_mode	service ID	queue type
499	Other	enq: JS - wdw op	name_mode	service ID	queue type
500	Other	enq: KK - context	name_mode	0	redo thread
501	Other	enq: KM - contention	name_mode	type	type
502	Other	enq: KP - contention	name_mode	0	0
503	Other	enq: KT - contention	name_mode	plan #	0
504	Other	enq: MD - contention	name_mode	master object #	0
505	Other	enq: MH - contention	name_mode	0	0
506	Other	enq: MK - contention	name_mode	0	0
507	Other	enq: ML - contention	name_mode	0	0
508	Other	enq: MN - contention	name_mode	session ID	0
509	Other	enq: MR - contention	name_mode	0 or file #	type
510	Other	enq: MS - contention	name_mode	master object #	0
511	Other	enq: MW - contention	name_mode	Schedule Id	0
512	Other	enq: OC - contention	name_mode	1	2
513	Other	enq: OL - contention	name_mode	hash value	0
514	Other	enq: OQ - xsoq*histrecb	name_mode	resource id	0
515	Other	enq: OQ - xsoqhiAlloc	name_mode	resource id	0
516	Other	enq: OQ - xsoqhiClose	name_mode	resource id	0
517	Other	enq: OQ - xsoqhiFlush	name_mode	resource id	0
518	Other	enq: OQ - xsoqhistrecb	name_mode	resource id	0
519	Other	enq: OW - initialization	name_mode	0	0
520	Other	enq: OW - termination	name_mode	0	0
521	Other	enq: PD - contention	name_mode	property name	key hash
522	Other	enq: PE - contention	name_mode	parno	0
523	Other	enq: PF - contention	name_mode	0	0
524	Other	enq: PG - contention	name_mode	0	0
525	Other	enq: PH - contention	name_mode	0	0
526	Other	enq: PI - contention	name_mode	operation	serial #
527	Other	enq: PL - contention	name_mode	0	0
528	Other	enq: PR - contention	name_mode	0	0
529	Other	enq: PS - contention	name_mode	instance	slave ID
530	Other	enq: PT - contention	name_mode	disk group #	type
531	Other	enq: PV - syncshut	name_mode	0	0
532	Other	enq: PV - syncstart	name_mode	0	0
533	Other	enq: PW - perwarm status in dbw0	name_mode	0	0
534	Other	enq: RB - contention	name_mode	disk group	0
535	Other	enq: RF - RF - Database Automatic Disable	name_mode	lock operation	lock value
536	Other	enq: RF - RF - FSFO Observed	name_mode	lock operation	lock value
537	Other	enq: RF - RF - FSFO connectivity	name_mode	lock operation	lock value
538	Other	enq: RF - RF - FSFO state	name_mode	lock operation	lock value
539	Other	enq: RF - RF - FSFO synchronization	name_mode	lock operation	lock value
540	Other	enq: RF - RF - FSFO wait	name_mode	lock operation	lock value
541	Other	enq: RF - atomicity	name_mode	lock operation	lock value
542	Other	enq: RF - new AI	name_mode	lock operation	lock value
543	Other	enq: RF - synch: DG Broker metadata	name_mode	lock operation	lock value
544	Other	enq: RF - synchronization: HC master	name_mode	lock operation	lock value
545	Other	enq: RF - synchronization: aifo master	name_mode	lock operation	lock value
546	Other	enq: RF - synchronization: chief	name_mode	lock operation	lock value
547	Other	enq: RF - synchronization: critical ai	name_mode	lock operation	lock value
548	Other	enq: RN - contention	name_mode	thread number	log number
549	Other	enq: RP - contention	name_mode	file #	1 or block
550	Other	enq: RS - file delete	name_mode	record type	record id
551	Other	enq: RS - persist alert level	name_mode	record type	record id
552	Other	enq: RS - prevent aging list update	name_mode	record type	record id
553	Other	enq: RS - prevent file delete	name_mode	record type	record id
554	Other	enq: RS - read alert level	name_mode	record type	record id
555	Other	enq: RS - record reuse	name_mode	record type	record id
556	Other	enq: RS - write alert level	name_mode	record type	record id
557	Other	enq: RT - contention	name_mode	redo thread	type
558	Other	enq: RU - contention	name_mode	0	0
559	Other	enq: RU - waiting	name_mode	0	0
560	Other	enq: RW - MV metadata contention	name_mode	table obj#	0
561	Other	enq: SB - contention	name_mode	0	0
562	Other	enq: SE - contention	name_mode	Session-id	Serial#
563	Other	enq: SF - contention	name_mode	0	0
564	Other	enq: SH - contention	name_mode	0	0
565	Other	enq: SI - contention	name_mode	object #	0
566	Other	enq: SK - contention	name_mode	tablespace #	dba
567	Other	enq: SR - contention	name_mode	operation	sequence # / apply #
568	Other	enq: SU - contention	name_mode	table space #	0
569	Other	enq: SW - contention	name_mode	0	0
570	Other	enq: TA - contention	name_mode	operation	undo segment # / other
571	Other	enq: TB - SQL Tuning Base Cache Load	name_mode	1	2
572	Other	enq: TB - SQL Tuning Base Cache Update	name_mode	1	2
573	Other	enq: TC - contention	name_mode	checkpoint ID	0
574	Other	enq: TC - contention2	name_mode	checkpoint ID	0
575	Other	enq: TD - KTF dump entries	name_mode	0	0
576	Other	enq: TE - KTF broadcast	name_mode	0	0
577	Other	enq: TF - contention	name_mode	tablespace #	relative file #
578	Other	enq: TL - contention	name_mode	0	0
579	Other	enq: TO - contention	name_mode	object #	1
580	Other	enq: TQ - DDL contention	name_mode	QT_OBJ#	0
581	Other	enq: TQ - INI contention	name_mode	QT_OBJ#	0
582	Other	enq: TQ - TM contention	name_mode	QT_OBJ#	0
583	Other	enq: TS - contention	name_mode	tablespace ID	dba
584	Other	enq: TT - contention	name_mode	tablespace ID	operation
585	Other	enq: TX - contention	name_mode	usn<<16 _ slot	sequence
586	Other	enq: US - contention	name_mode	undo segment #	0
587	Other	enq: WA - contention	name_mode	0	0
588	Other	enq: WF - contention	name_mode	0	0
589	Other	enq: WL - contention	name_mode	log # / thread id #	sequence #
590	Other	enq: WP - contention	name_mode	0	0
591	Other	enq: WR - contention	name_mode	thread id #	sequence #
592	Other	enq: XH - contention	name_mode	0	0
593	Other	enq: XQ - recovery	name_mode	disk group #	unused
594	Other	enq: XQ - relocation	name_mode	disk group #	unused
595	Other	enq: XR - database force logging	name_mode	operation	0
596	Other	enq: XR - quiesce database	name_mode	operation	0
597	Other	enq: XY - contention	name_mode	id1	id2
598	Other	events in waitclass Other
599	Other	extent map load/unlock	group	file	extent
600	Other	flashback buf free by RVWR
601	Other	flashback free VI log
602	Other	flashback log switch
603	Other	free global transaction table entry	tries
604	Other	free process state object
605	Other	gcs ddet enter server mode
606	Other	gcs domain validation	cluinc	rcvinc
607	Other	gcs drm freeze begin
608	Other	gcs drm freeze in enter server mode
609	Other	gcs enter server mode
610	Other	gcs log flush sync	waittime	poll	event
611	Other	gcs remastering wait for read latch
612	Other	gcs remastering wait for write latch
613	Other	gcs resource directory to be unfrozen
614	Other	gcs to be enabled
615	Other	ges LMD suspend for testing event
616	Other	ges LMD to inherit communication channels
617	Other	ges LMD to shutdown
618	Other	ges LMON for send queues
619	Other	ges LMON to get to FTDONE
620	Other	ges LMON to join CGS group
621	Other	ges cached resource cleanup	waittime
622	Other	ges cancel
623	Other	ges cgs registration	where
624	Other	ges enter server mode
625	Other	ges generic event
626	Other	ges global resource directory to be frozen
627	Other	ges inquiry response	type_mode_where	id1	id2
628	Other	ges lmd and pmon to attach
629	Other	ges lmd/lmses to freeze in rcfg - mrcvr
630	Other	ges lmd/lmses to unfreeze in rcfg - mrcvr
631	Other	ges master to get established for SCN op
632	Other	ges performance test completion
633	Other	ges pmon to exit
634	Other	ges process with outstanding i/o	pid
635	Other	ges reconfiguration to start
636	Other	ges resource cleanout during enqueue open
637	Other	ges resource cleanout during enqueue open-cvt
638	Other	ges resource directory to be unfrozen
639	Other	ges retry query node
640	Other	ges reusing os pid	pid	count
641	Other	ges user error	error
642	Other	ges wait for lmon to be ready
643	Other	ges1 LMON to wake up LMD - mrcvr
644	Other	ges2 LMON to wake up LMD - mrcvr
645	Other	ges2 LMON to wake up lms - mrcvr 2
646	Other	ges2 LMON to wake up lms - mrcvr 3
647	Other	ges2 proc latch in rm latch get 1
648	Other	ges2 proc latch in rm latch get 2
649	Other	global cache busy	group	file#	block#
650	Other	global enqueue expand wait
651	Other	imm op	msg ptr
652	Other	inactive session	session#	waited
653	Other	inactive transaction branch	branch#	waited
654	Other	index block split	rootdba	level	childdba
655	Other	instance state change	layer	value	waited
656	Other	job scheduler coordinator slave wait
657	Other	jobq slave TJ process wait
658	Other	jobq slave shutdown wait
659	Other	kcbzps
660	Other	kcrrrcp
661	Other	kdic_do_merge
662	Other	kfcl: instance recovery	group	obj#	block#
663	Other	kgltwait
664	Other	kjbdomalc allocate recovery domain - retry
665	Other	kjbdrmcvtq lmon drm quiesce: ping completion
666	Other	kjbopen wait for recovery domain attach
667	Other	kjctcisnd: Queue/Send client message
668	Other	kjctssqmg: quick message send wait
669	Other	kjudomatt wait for recovery domain attach
670	Other	kjudomdet wait for recovery domain detach
671	Other	kjxgrtest
672	Other	kkdlgon
673	Other	kkdlhpon
674	Other	kkdlsipon
675	Other	kksfbc child completion
676	Other	kksfbc research
677	Other	kkshgnc reloop
678	Other	kksscl hash split
679	Other	knpc_acwm_AwaitChangedWaterMark
680	Other	knpc_anq_AwaitNonemptyQueue
681	Other	knpsmai
682	Other	ksbcic
683	Other	ksbsrv
684	Other	ksdxexeother
685	Other	ksdxexeotherwait
686	Other	ksim generic wait event	where	wait_count
687	Other	ksqded
688	Other	ksv slave avail wait
689	Other	ksxr poll remote instances
690	Other	ksxr wait for mount shared
691	Other	ktfbtgex	tsn
692	Other	ktm: instance recovery	undo segment#
693	Other	ktsambl
694	Other	kttm2d
695	Other	kupp process wait
696	Other	kxfxse	kxfxse debug wait: stalling for slave 0
697	Other	kxfxsp	kxfxsp debug wait: stalling for slave 0
698	Other	latch activity	address	number	process#
699	Other	latch free	address	number	tries
700	Other	latch: Change Notification Hash table latch	address	number	tries
701	Other	latch: KCL gc element parent latch	address	number	tries
702	Other	latch: cache buffer handles	address	number	tries
703	Other	latch: cache buffers lru chain	address	number	tries
704	Other	latch: checkpoint queue latch	address	number	tries
705	Other	latch: enqueue hash chains	address	number	tries
706	Other	latch: gcs resource hash	address	number	tries
707	Other	latch: ges resource hash list	address	number	tries
708	Other	latch: messages	address	number	tries
709	Other	latch: object queue header heap	address	number	tries
710	Other	latch: object queue header operation	address	number	tries
711	Other	latch: parallel query alloc buffer	address	number	tries
712	Other	latch: redo allocation	address	number	tries
713	Other	latch: session allocation	address	number	tries
714	Other	latch: undo global data	address	number	tries
715	Other	latch: virtual circuit queues	address	number	tries
716	Other	library cache revalidation
717	Other	library cache shutdown
718	Other	listen endpoint status	end-point#	status
719	Other	lms flush message acks	loc	tries
720	Other	lock close	group	lms#
721	Other	lock deadlock retry
722	Other	lock escalate retry
723	Other	lock release pending	group	file#	block#
724	Other	log file switch (clearing log file)
725	Other	log switch/archive	thread#
726	Other	log write(even)	group#
727	Other	log write(odd)	group#
728	Other	master exit	alive slaves
729	Other	name-service call wait	waittime
730	Other	no free buffers	group#	obj#	block#
731	Other	no free locks
732	Other	null event
733	Other	opishd
734	Other	optimizer stats update retry
735	Other	pending global transaction(s)	scans
736	Other	prewarm transfer retry
737	Other	prior spawner clean up	process_pid	process_sno
738	Other	process shutdown	type	process#	waited
739	Other	process startup	type	process#	waited
740	Other	process terminate
741	Other	qerex_gdml
742	Other	queue slave messages
743	Other	rdbms ipc message block
744	Other	rdbms ipc reply	from_process	timeout
745	Other	recovery area: computing applied logs
746	Other	recovery area: computing backed up files
747	Other	recovery area: computing dropped files
748	Other	recovery area: computing identical files
749	Other	recovery area: computing obsolete files
750	Other	reliable message	channel context	channel handle	broadcast message
751	Other	rfi_drcx_site_del	DRCX waiting for site to delete metadata
752	Other	rfi_insv_shut	wait for INSV to shutdown
753	Other	rfi_insv_start	wait for INSV to start
754	Other	rfi_nsv_deldef	NSVx to defer delete response message post to DMON
755	Other	rfi_nsv_md_close	NSVx metadata file close wait
756	Other	rfi_nsv_md_write	NSVx metadata file write wait
757	Other	rfi_nsv_postdef	NSVx to defer message post to DMON
758	Other	rfi_nsv_shut	wait for NSVx to shutdown
759	Other	rfi_nsv_start	wait for NSVx to start
760	Other	rfi_recon1	letting site register with its local listener before connect ret
761	Other	rfi_recon2	retrying connection for sending to remote DRCX
762	Other	rfm_dmon_last_gasp	DMON waiting on the last gasp event
763	Other	rfm_dmon_pdefer	DMON phase deferral wait
764	Other	rfm_dmon_shut	wait for DMON to shutdown
765	Other	rfm_dmon_timeout_op	DMON waiting to timeout an operation
766	Other	rfm_pmon_dso_stall	PMON delete state object stall
767	Other	rfrdb_dbop	waiting for database to be opened
768	Other	rfrdb_recon1	reconnecting back to new primary site during standby viability c
769	Other	rfrdb_recon2	waiting for standby database to be mounted
770	Other	rfrdb_try235	waiting for retrying the query to mask ORA-235 error
771	Other	rfrla_lapp1	waiting for logical apply engine to initialize
772	Other	rfrla_lapp2	checking for logical apply engine run-down progress
773	Other	rfrla_lapp3	waiting for new primary to initialize tables
774	Other	rfrla_lapp4	waiting for v$logstdby_stats view to be initialized
775	Other	rfrla_lapp5	waiting to reconnect to primary that is in BUILD_UP
776	Other	rfrld_rhmrpwait	waiting for MRP0 to stop while reinstating old primary to logica
777	Other	rfrm_dbcl	RSM notifier: waiting for sql latch on db close
778	Other	rfrm_dbop	RSM notifier: waiting for sql latch on db open
779	Other	rfrm_nonzero_sub_count	wait for subscriber count to become nonzero
780	Other	rfrm_rsm_shut	wait for RSMx processes to shutdown
781	Other	rfrm_rsm_so_attach	wait for RSMx to attach to state object
782	Other	rfrm_rsm_start	wait for RSMx processes to start
783	Other	rfrm_stall	RSM stall due to event RSM_STALL
784	Other	rfrm_zero_sub_count	wait for subscriber count to become zero
785	Other	rfrpa_mrpdn	waiting for MRP0 to stop while bringing physical apply engine of
786	Other	rfrpa_mrpup	waiting for MRP0 to start while bringing physical apply engine o
787	Other	rfrxpt_pdl	waiting for retrying potential dataloss calculation before switc
788	Other	rfrxptarcurlog	waiting for logical apply engine to finish initialization
789	Other	rollback operations active	operation count
790	Other	rollback operations block full	max operations
791	Other	rolling migration: cluster quiesce	location	waits
792	Other	scginq AST call
793	Other	secondary event	event #	wait time
794	Other	select wait
795	Other	set director factor wait
796	Other	simulated log write delay
797	Other	slave exit	nalive	sleeptime	loop
798	Other	test long ops
799	Other	timer in sksawat
800	Other	transaction	undo seg#_slot#	wrap#	count
801	Other	tsm with timeout
802	Other	txn to complete
803	Other	unbound tx
804	Other	undo segment recovery	segment#	tx flags
805	Other	undo_retention publish retry	where	retry_count
806	Other	unspecified wait event
807	Other	wait active processes
808	Other	wait for EMON to die
809	Other	wait for EMON to spawn
810	Other	wait for FMON to come up
811	Other	wait for MTTR advisory state object
812	Other	wait for a paralle reco to abort
813	Other	wait for a undo record
814	Other	wait for another txn - rollback to savepoint
815	Other	wait for another txn - txn abort
816	Other	wait for another txn - undo rcv abort
817	Other	wait for assert messages to be sent
818	Other	wait for change
819	Other	wait for master scn	waittime	startscn	ackscn
820	Other	wait for membership synchronization
821	Other	wait for message ack
822	Other	wait for record update
823	Other	wait for rr lock release
824	Other	wait for scn ack	pending_nd	scnwrp	scnbas
825	Other	wait for split-brain resolution
826	Other	wait for stopper event to be increased
827	Other	wait for sync ack	cluinc	pending_nd
828	Other	wait for tmc2 to complete
829	Other	wait for verification ack	cluinc	pending_insts
830	Other	wait for votes
831	Other	wait list latch activity	address	number	process#
832	Other	wait list latch free	address	number	tries
833	Other	waiting to get CAS latch
834	Other	waiting to get RM CAS latch
835	Other	writes stopped by instance recovery or database suspension	by thread#	our thread#
836	Scheduler	resmgr:become active	location
837	Scheduler	resmgr:cpu quantum	location
838	System I/O	ARCH random i/o
839	System I/O	ARCH sequential i/o
840	System I/O	ARCH wait for pending I/Os
841	System I/O	LGWR random i/o
842	System I/O	LGWR sequential i/o
843	System I/O	LNS ASYNC control file txn
844	System I/O	Log archive I/O	count	intr	timeout
845	System I/O	RFS random i/o
846	System I/O	RFS sequential i/o
847	System I/O	RFS write
848	System I/O	RMAN backup & recovery I/O	count	intr	timeout
849	System I/O	Standby redo I/O	count	intr	timeout
850	System I/O	control file parallel write	files	block#	requests
851	System I/O	control file sequential read	file#	block#	blocks
852	System I/O	control file single write	file#	block#	blocks
853	System I/O	db file parallel write	requests	interrupt	timeout
854	System I/O	io done	msg ptr
855	System I/O	kfk: async disk IO	count	intr	timeout
856	System I/O	ksfd: async disk IO	count	intr	timeout
857	System I/O	kst: async disk IO	count	intr	timeout
858	System I/O	log file parallel write	files	blocks	requests
859	System I/O	log file sequential read	log#	block#	blocks
860	System I/O	log file single write	log#	block#	blocks
861	System I/O	recovery read
862	User I/O	BFILE read
863	User I/O	DG Broker configuration file I/O	count	intr	timeout
864	User I/O	Data file init write	count	intr	timeout
865	User I/O	Datapump dump file I/O	count	intr	timeout
866	User I/O	Log file init write	count	intr	timeout
867	User I/O	buffer read retry	file#	block#
868	User I/O	db file parallel read	files	blocks	requests
869	User I/O	db file scattered read	file#	block#	blocks
870	User I/O	db file sequential read	file#	block#	blocks
871	User I/O	db file single write	file#	block#	blocks
872	User I/O	dbms_file_transfer I/O	count	intr	timeout
873	User I/O	direct path read	file number	first dba	block cnt
874	User I/O	direct path read temp	file number	first dba	block cnt
875	User I/O	direct path write	file number	first dba	block cnt
876	User I/O	direct path write temp	file number	first dba	block cnt
877	User I/O	local write wait	file#	block#
878	User I/O	read by other session	file#	block#	class#

대기 이벤트를 시스템 커널 레벨에서 표현
- 프로세스가 할 일을 모두 마쳤거나 다른 프로세스를 기다려야 하는 상황에서 CPU를 쥔 채 대기하면 불필요하게 CPY 자원을 낭비하므로
  CPU를 OS에 반환하고 Sleep 상태로 빠지는 것을 말함.
- 수면에 빠진다는 것은 프로세스가 'wait queue'로 옮겨지는 것을 말하며, 'wait queue'에 놓인 프로세스에게는 CPY를 할당해 줄 필요가
  없으므로 OS는 해당 프로세스를 스케쥴링 대상에서 제외시킴
- 선행 프로세스가 일을 마치면 OS에게 그 사실을 알려 자신을 기다리던 수면 상태의 프로세스를 깨우도록 신호를 보냄(interrupted)
  그러면 OS는 그 프로세스를 'runnable queue'에 옮김으로써 가능한 한 빨리 CPY를 할다 받아 일을 재개할 수 있도록 스케쥴링 함.

유닉스에서 vmstat 유틸리티를 통해 시스템 상황을 모니터링 한 결과


> vmstat -t 60 1000

vmstat 명령어
- 서버의 가상 메모리 통계정보를 보기위한 명령어
- vmstat 명령은 커널 스레드, 가상 메모리, 디스크, 트랩 및 CPU 활동에 대한 통계를 보고함.
- vmstat 명령으로 작성된 보고서는 시스템 로드 활동의 균형을 유지하는 데 사용될 수 있으며
  이 시스템 전반에 대한 통계(모든 프로세서 중에서의 통계)는 비율로 표시된 값의 평균 또는 합계로 계산됨.
- 구문


vmstat [ -f ] [ -i ] [ -s ] [ -I ] [ -t ] [ -v ] [ -w] [ -l ] [ { -p | -P } pagesize | ALL ] ALL ] [ PhysicalVolume ... ] [ Interval [ Count ] ]

-t   : 출력의 각 행 다음에 시간 소인을 출력하며 시간 소인은 HH:MM:SS 형식으로 표시됨
60   : 60초 간격으로 출력하도록 함
1000 : 한번에 1000개의 로우를 출력하도록 함

출력 결과

r	b	avm	fre	pi	fr	sr	in	sy	cs	us	sy	id	wa	hr mi se
7	24	3132936	2000	0	5186	27716	5546	40941	14037	40	6	8	45	08:48:06
7	26	3137616	2062	1	7389	47361	5787	42744	17656	41	8	8	43	08:49:06
9	33	3145090	2081	1	7047	37573	5813	57915	20228	43	9	5	44	08:50:06
7	55	3140985	9712	1	9142	51835	8203	39344	20428	37	9	2	52	08:51:06
7	52	3152171	2001	1	8396	51356	7999	40604	20296	36	9	2	53	08:52:06

항목 설명

대분류	소분류	설명
kthr	r	현재 일을 수행 중이거나 runnable queue에서 CPU 리소스를 기다리는 프로세스 개수
	b	샘플 간격을 통해 VMM 대기행렬에서 대기 중인 커널 스레드의 평균 개수(대기 중인 자원, 대기 중인 입출력)
memory	avm	사용 중인 가상 페이지
	fre	사용 가능 리스트의 크기(실제 메모리의 많은 부분이 파일 시스템 데이터를 위한 캐쉬로 이용되며 사용 가능 리스트 크기의 양이 적게 남는 일은 드뭄)
page	re	호출기 입출력 리스트
	pi	페이징 공간에서 들어오는 페이지
	po	페이징 공간으로 나가는 페이지
	fr	사용 가능 페이지(페이지 교체)
	sr	페이지 교체 알고리즘에 의해 스캔되는 페이지
	cy	페이지 교체 알고리즘에 의한 시간 주기
faults	in	장치 인터럽트
	sy	시스템 호출
	cs	커널 스레드 문맥 전환
cpu	us	사용자 시간
	sy	시스템 시간
	id	CPU 유휴 시간
	wa	시스템이 미결 디스크/NFS 입출력 요청을 보유하는 동안의 CPU 유휴 시간
time	hr mi ss	시분초

2. 대기 이벤트는 언제 발생하나?

1. 자신이 필요로 하는 특정 리소스가 다른 프로세스에 의해 사용중일 때

자신이 읽으려는 버퍼에 다른 프로세스가 쓰기 작업을 진행 중이라면 선행 프로세스가 일을 마칠 때까지 기다려야 하며
'buffer busy waits', 'latch free', 'enqueue' 이벤트 등이 여기에 속함

2. 다른 프로세스에 의해 선행작업이 완료되기를 기다릴 때

DBWR가 Dirty 버퍼를 디스크에 기록할 때, 먼저 LGWR가 로그 버퍼에 있는 Redo Entry를 Redo Log 파일에 기록하는 작업이
선행되야 하는데 이 때 DBWR는 LGWR를 깨워 로그 버퍼를 비우라는 신호를 보내고 LGWR가 일을 마칠 때까지 수면 상태에서
휴식을 취함.
LGWR가일을 마치면 DBWR를 개ㅜ고 자신은 다시 대기 상태로 빠지며, 'write complete waits', 'checkpoint completed',
'log file sync', 'log file switch' 이벤트 등이 여기에 속함

3. 할 일이 없을 때(idle 대기 이벤트)

서버 프로세스는 쿼리 결과를 사용자에게 전송하는 동안 Array 단위로 일을 처리하는데, Array 크기만큼 데이터를 전송하면
다음 Fetch Call을 받을 때까지 기다림. 쿼리 결과집합을 모두 전송하고 나서도 다음 Parse Call 또는 Execute Call을 받을
때까지 기다리며 'SQL*Net message from client' 등이 여기에 속함

3. 대기 이벤트는 언제 사라지나?

오라클 프로세스가 자신이 작업을 진행할 대 선행 프로세스가 먼저 점유하여 대기 상태에 빠질 경우 선행작업이 끝나고 나서
자신에게 알려주어 일을 진행하거나, 타이머에 설정된 시간에 깨어나 선행 프로세스가 작업을 모두 마쳤는지 확인할 때 사라짐

1. 대기 상태에 빠진 프로세스가 기다리던 리소스를 사용할 수 있게 될 경우
2. 작업을 계속 진행하기 위한 선행작업이 완료될 경우
3. 해야 할 일이 생겼을 경우

4. 래치와 대기 이벤트 개념 명확화

래치는 공유된 자원을 읽기 위해서는 반드시 획득해야 하기 때문에 래치가 증가한다고 해서 문제가 되진 않음
다만 획득하는 과정에서 다른 프로세스와 경합이 발생되는지를 모니터링 해야 하며 이 때 발생되는 대기 이벤트를 분석해야 함
래치 확인


SELECT *
FROM   (SELECT ADDR,
               LATCH#,
               LEVEL#,
               NAME,
               GETS,
               MISSES,
               SPIN_GETS,
               SLEEPS
        FROM   V$LATCH
        ORDER BY 2)
WHERE  ROWNUM <= 10
;

ADDR             LATCH# LEVEL# NAME                        GETS   MISSES  SPIN_GETS SLEEPS
---------------- ------ ------ ----------------------- -------- -------- ---------- ------
0700000010006FB8      0      8 event range base latch         1        0          0      0
0700000010007058      1      8 post/wait queue             1388       17         17      0
07000000100070F8      2      0 hot latch diags                0        0          0      0
07000000100074D0      3      1 process allocation          1064        0          0      0
0700000010007570      4      5 session allocation      16031367 10427696   10426488   1238
0700000010007618      5      0 session switching           1222        0          0      0
07000000100076B8      6      0 process group creation       926        8          8      0
0700000010007758      7      1 session idle bit          111772       91         91      0
0700000010007808      8      7 client/application info     8554        0          0      0
0700000010007EB0      9      8 longop free list parent    39705        0          0      0
;

항목	설명
ADDR	래치 오브젝트 주소
LATCH#	래치 번호
LEVEL#	래치 레벨
NAME	래치 이름
GETS	래치 요청 횟수
MISSES	래치를 요청했는데 다른 프로세스에 의해 자원이 사용 중이어서 첫 번째 시도에서 바로 래치를 얻지 못한 횟수
SPIN_GETS	래치를 요청한 첫 번째 시도에서 곧바로 래치를 얻지는 못했지만 이후 spin하는 과정에서 래치 획득에 성공한 횟수
SLEEPS	래치를 요청했는데 자원이 사용 중어어서 곧바로 래치를 얻지 못하고 정해진 횟수만큼 계속 spin 했는데도 결국 래치를 얻지 못해 대기 상태로 빠진 횟수. 이때 발생하는 것이 'latch free' 이벤트. 10g 이후부터는 이 이벤트를 세분화하여 'latch : cache buffers chains', 'latch : library cache lock'

래치 관련 추가 참고 사이트
- /wiki/pages/1343499
- http://wiki.ex-em.com/index.php/Latch_free

문서에 대하여

최초작성자 : xsoft
최초작성일 : 2009년 10월 22일
이 문서는 오라클클럽 코어 오라클 데이터베이스 스터디 모임에서 작성하였습니다.
{*}이 문서의 내용은 (주)비투엔컬설팅에서 출간한 '오라클 성능 고도화 원리와 해법I'를 참고하였습니다.*

참고자료

LINUX SARANG NET

대기이벤트 (by xsoft) [2009.10.21]

목차

1. 대기 이벤트(Wait Event)란?

2. 대기 이벤트는 언제 발생하나?

3. 대기 이벤트는 언제 사라지나?

4. 래치와 대기 이벤트 개념 명확화

문서에 대하여

참고자료