Waits and Queues and You. Thomas LaRock Senior DBA, Confio Software

Transcription

1 Waits and Queues and You Thomas LaRock Senior DBA, Confio Software 1

2 Who Am

3 3 Learning to Drive

4 4 Learning to DBA

5 5 Car Engine

6 SQL Server is a Black Box INPUT OUTPUT 6

7 7 SQLOS

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9 9 SQLOS

10 Agenda Describe Execution Model 10

11 Agenda Describe Execution Model Use some DMVs 11

12 Agenda Describe Execution Model Use some DMVs Show why we measure waits (use case) 12

13 13 Execution Model Example

14 14 Your Tax Dollars at Work

15 15 Your Tax Dollars at Work

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20 Execution Model (TSA) Passport checked Assigned a lane Put stuff on belt Freedom Pat Head to gate 20

21 Execution Model (SQLOS) Init Runnable Waiting Running Done 21

22 Execution Model (SQLOS) CPU 1 SPID 77 Running CPU 1 Queue Waiter Queue SPID 62 ASYNC_NETWORK_IO SPID 63 CXPACKET SPID 67 PAGEIOLATCH_SH SPID 74 LCK_M_S SPID 79 LATCH_EX SPID 87 WRITELOG SPID 81 Runnable SPID 91 Runnable 22

23 Execution Model (SQLOS) CPU 1 SPID 77 Running CPU 1 Queue Waiter Queue SPID 62 ASYNC_NETWORK_IO SPID 63 CXPACKET SPID 67 PAGEIOLATCH_SH SPID 74 LCK_M_S SPID 79 LATCH_EX SPID 87 WRITELOG SPID 81 Runnable SPID 91 Runnable SPID 67 Runnable 23

24 Execution Model (SQLOS) CPU 1 SPID 77 Running CPU 1 Queue Waiter Queue SPID 62 ASYNC_NETWORK_IO SPID 63 CXPACKET SPID 67 PAGEIOLATCH_SH SPID 74 LCK_M_S SPID 77 LCK_M_IX SPID 79 LATCH_EX SPID 87 WRITELOG SPID 81 Runnable SPID 91 Runnable SPID 67 Runnable 24

25 Execution Model (SQLOS) CPU 1 SPID 81 Running CPU 1 Queue Waiter Queue SPID 62 ASYNC_NETWORK_IO SPID 63 CXPACKET SPID 67 PAGEIOLATCH_SH SPID 74 LCK_M_S SPID 79 LATCH_EX SPID 87 WRITELOG SPID 77 LCK_M_IX SPID 81 Runnable SPID 91 Runnable SPID 67 Runnable 25

26 Execution Model (SQLOS) CPU 1 SPID 77 Running CPU 1 Queue Waiter Queue SPID 62 ASYNC_NETWORK_IO SPID 63 CXPACKET SPID 67 PAGEIOLATCH_SH SPID 74 LCK_M_S SPID 79 LATCH_EX SPID 87 WRITELOG SPID 81 Runnable SPID 91 Runnable 26

27 Execution Model (SQLOS) CPU 1 SPID 77 Running CPU 1 Queue Waiter Queue SPID 62 ASYNC_NETWORK_IO SPID 63 CXPACKET SPID 67 PAGEIOLATCH_SH SPID 74 LCK_M_S SPID 79 LATCH_EX SPID 87 WRITELOG SPID 81 Runnable SPID 91 Runnable 27

28 Execution Model (SQLOS) CPU 1 SPID 77 Running CPU 1 Queue Waiter Queue SPID 62 ASYNC_NETWORK_IO SPID 63 CXPACKET SPID 67 PAGEIOLATCH_SH SPID 74 LCK_M_S SPID 79 LATCH_EX SPID 87 WRITELOG SPID 81 Runnable SPID 91 Runnable 28

29 Execution Model (DMVs) Init Runnable Waiting Running Done 29

30 Execution Model (DMVs) sys.dm_exec_sessions sys.dm_exec_requests = runnable sys.dm_os_waiting_tasks sys.dm_exec_requests = running sys.dm_exec_connections 30

31 Demo DEMO 31

32 Sample Wait Types

33 Sample Wait Types LCK_M_S, LCK_M_U, LCK_M_X 33

34 Sample Wait Types LCK_M_S, LCK_M_U, LCK_M_X Waiting to acquire locks 34

35 Sample Wait Types PAGEIOLATCH_SH, PAGEIOLATCH_EX 5. LCK_M_S, LCK_M_U, LCK_M_X Waiting to acquire locks 35

36 Sample Wait Types PAGEIOLATCH_SH, PAGEIOLATCH_EX Physical disk reads 5. LCK_M_S, LCK_M_U, LCK_M_X Waiting to acquire locks 36

37 Sample Wait Types WRITELOG 4. PAGEIOLATCH_SH, PAGEIOLATCH_EX Physical disk reads 5. LCK_M_S, LCK_M_U, LCK_M_X Waiting to acquire locks 37

38 Sample Wait Types WRITELOG Waiting for a log flush to complete 4. PAGEIOLATCH_SH, PAGEIOLATCH_EX Physical disk reads 5. LCK_M_S, LCK_M_U, LCK_M_X Waiting to acquire locks 38

39 Sample Wait Types CXPACKET 3. WRITELOG Waiting for a log flush to complete 4. PAGEIOLATCH_SH, PAGEIOLATCH_EX Physical disk reads 5. LCK_M_S, LCK_M_U, LCK_M_X Waiting to acquire locks 39

40 Sample Wait Types CXPACKET Parallelism 3. WRITELOG Waiting for a log flush to complete 4. PAGEIOLATCH_SH, PAGEIOLATCH_EX Physical disk reads 5. LCK_M_S, LCK_M_U, LCK_M_X Waiting to acquire locks 40

41 Sample Wait Types 1. ASYNC_NETWORK_IO, NETWORKIO 2. CXPACKET Parallelism 3. WRITELOG Waiting for a log flush to complete 4. PAGEIOLATCH_SH, PAGEIOLATCH_EX Physical disk reads 5. LCK_M_S, LCK_M_U, LCK_M_X Waiting to acquire locks 41

42 Sample Wait Types 1. ASYNC_NETWORK_IO, NETWORKIO Waiting on the network 2. CXPACKET Parallelism 3. WRITELOG Waiting for a log flush to complete 4. PAGEIOLATCH_SH, PAGEIOLATCH_EX Physical disk reads 5. LCK_M_S, LCK_M_U, LCK_M_X Waiting to acquire locks 42

43 Why Measure Waits? Think about how you currently resolve performance issues, does it look like this? 43

44 Why Measure Waits? Think about how you currently resolve performance issues, does it look like this? 44

45 Why Wait Time Analysis Rocks Allows you to focus on *the* problem Four possible resource bottlenecks 45

46 Why Wait Time Analysis Rocks Allows you to focus on *the* problem Four possible resource bottlenecks Waits help you to answer the BIG question: Is this a problem? 46

47 Why Wait Time Analysis Rocks Allows you to focus on *the* problem Four possible resource bottlenecks Waits help you to answer the BIG question: Is this a problem? Helps to prioritize Fix the ones you can fix now 47

48 Why Wait Time Analysis Rocks Allows you to focus on *the* problem Four possible resource bottlenecks Waits help you to answer the BIG question: Is this a problem? Helps to prioritize Fix the ones you can fix now Does not rely on Health Stats alone Perfmon counters only? 48

49 49 Use Case (or, My Story)

50 How To Measure? 3 rd party tools Native tools DMVs Perfmon xevents MDW/UCP 50

51 Know What You Are Measuring Know difference between wait and queue Wait Any time a session is waiting Queue A measure of system resource and utilization (think perfmon) 51

52 Know What You Are Measuring Know difference between wait and queue Wait Any time a session is waiting Queue A measure of system resource and utilization (think perfmon) Difference between OLTP and OLAP Which one has more ad-hoc queries? Which one is more likely to see parallelism? Which one is likely to see more blocking/locking? 52

53 Know What You Are Measuring Know difference between wait and queue Wait Any time a session is waiting Queue A measure of system resource and utilization (think perfmon) Difference between OLTP and OLAP Which one has more ad-hoc queries? Which one is more likely to see parallelism? Which one is likely to see more blocking/locking? What does all that mean to the DBA? 53

54 54 Operating With Precision

55 For More Information 1/19/sql-server-2005-waits-and-queues.aspx 55

56 For More Information sqlrockstar 56

57 Thanks! THANK YOU DALLAS! NEXT STOP: LOUISVILLE! 57

58 58 Questions?