Identify Query Waiting on resources
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I have some query with CXCONSUMER wait time when i ran sp_whoisactive as shown in the screenshot below.
When i checked the status it is suspended.That means it is waiting for some process to release resource.As far as my understanding CXPACKET is the producer and CXCONSUMER is the consumer and CXPACKET is the main culprit and action should be taken on that.But i don't see any CXPACKET.
Since this is a parallel execution i am not sure where i should start fixing.
Can anyone suggest me how to find out the process on which my queries are waiting(because i see suspended as status)?
Additional Info
When i query sys.dm_os_wait_stats ,the top two entries are CONSUMER and CXPACKETS.
- SQL Server 2016
- 128 GB RAM
- MAX DOP : 8
- Cost of threshold : 20
sql-server performance-tuning parallelism blocking waits
asked Jan 4 at 19:14
user9516827user9516827
364110
add a comment |
I have some query with CXCONSUMER wait time when i ran sp_whoisactive as shown in the screenshot below.
When i checked the status it is suspended.That means it is waiting for some process to release resource.As far as my understanding CXPACKET is the producer and CXCONSUMER is the consumer and CXPACKET is the main culprit and action should be taken on that.But i don't see any CXPACKET.
Since this is a parallel execution i am not sure where i should start fixing.
Can anyone suggest me how to find out the process on which my queries are waiting(because i see suspended as status)?
Additional Info
When i query sys.dm_os_wait_stats ,the top two entries are CONSUMER and CXPACKETS.
- SQL Server 2016
- 128 GB RAM
- MAX DOP : 8
- Cost of threshold : 20
sql-server performance-tuning parallelism blocking waits
asked Jan 4 at 19:14
user9516827user9516827
364110
1
have you tried brentozar.com/blitz ? It's very usefull and have a part to identify waits (brentozar.com/sql/wait-stats )
– Danielle Paquette-Harvey
Jan 4 at 19:17
1
Check out what Paul Randal says about that wait. He also has some steps on working on CXPACKET as does Brent Ozar but as you said, you don't see this wait type.
– scsimon
Jan 4 at 19:28
1
@scsimon: I don't see CXPACKET when i runsp_whoisactive,i see only CXCONSUMER.I will check the links.
– user9516827
Jan 4 at 19:32
add a comment |
I have some query with CXCONSUMER wait time when i ran sp_whoisactive as shown in the screenshot below.
When i checked the status it is suspended.That means it is waiting for some process to release resource.As far as my understanding CXPACKET is the producer and CXCONSUMER is the consumer and CXPACKET is the main culprit and action should be taken on that.But i don't see any CXPACKET.
Since this is a parallel execution i am not sure where i should start fixing.
Can anyone suggest me how to find out the process on which my queries are waiting(because i see suspended as status)?
Additional Info
When i query sys.dm_os_wait_stats ,the top two entries are CONSUMER and CXPACKETS.
- SQL Server 2016
- 128 GB RAM
- MAX DOP : 8
- Cost of threshold : 20
sql-server performance-tuning parallelism blocking waits
asked Jan 4 at 19:14
user9516827user9516827
364110
I have some query with CXCONSUMER wait time when i ran sp_whoisactive as shown in the screenshot below.
When i checked the status it is suspended.That means it is waiting for some process to release resource.As far as my understanding CXPACKET is the producer and CXCONSUMER is the consumer and CXPACKET is the main culprit and action should be taken on that.But i don't see any CXPACKET.
Since this is a parallel execution i am not sure where i should start fixing.
Can anyone suggest me how to find out the process on which my queries are waiting(because i see suspended as status)?
Additional Info
When i query sys.dm_os_wait_stats ,the top two entries are CONSUMER and CXPACKETS.
- SQL Server 2016
- 128 GB RAM
- MAX DOP : 8
- Cost of threshold : 20
sql-server performance-tuning parallelism blocking waits
sql-server performance-tuning parallelism blocking waits
asked Jan 4 at 19:14
user9516827user9516827
364110
asked Jan 4 at 19:14
user9516827user9516827
364110
asked Jan 4 at 19:14
user9516827user9516827
364110
asked Jan 4 at 19:14
user9516827user9516827
364110
asked Jan 4 at 19:14
user9516827user9516827
364110
364110
1
have you tried brentozar.com/blitz ? It's very usefull and have a part to identify waits (brentozar.com/sql/wait-stats )
– Danielle Paquette-Harvey
Jan 4 at 19:17
1
Check out what Paul Randal says about that wait. He also has some steps on working on CXPACKET as does Brent Ozar but as you said, you don't see this wait type.
– scsimon
Jan 4 at 19:28
1
@scsimon: I don't see CXPACKET when i runsp_whoisactive,i see only CXCONSUMER.I will check the links.
– user9516827
Jan 4 at 19:32
add a comment |
1
have you tried brentozar.com/blitz ? It's very usefull and have a part to identify waits (brentozar.com/sql/wait-stats )
– Danielle Paquette-Harvey
Jan 4 at 19:17
1
Check out what Paul Randal says about that wait. He also has some steps on working on CXPACKET as does Brent Ozar but as you said, you don't see this wait type.
– scsimon
Jan 4 at 19:28
1
@scsimon: I don't see CXPACKET when i runsp_whoisactive,i see only CXCONSUMER.I will check the links.
– user9516827
Jan 4 at 19:32
1
1
have you tried brentozar.com/blitz ? It's very usefull and have a part to identify waits (brentozar.com/sql/wait-stats )
– Danielle Paquette-Harvey
Jan 4 at 19:17
have you tried brentozar.com/blitz ? It's very usefull and have a part to identify waits (brentozar.com/sql/wait-stats )
– Danielle Paquette-Harvey
Jan 4 at 19:17
1
1
Check out what Paul Randal says about that wait. He also has some steps on working on CXPACKET as does Brent Ozar but as you said, you don't see this wait type.
– scsimon
Jan 4 at 19:28
Check out what Paul Randal says about that wait. He also has some steps on working on CXPACKET as does Brent Ozar but as you said, you don't see this wait type.
– scsimon
Jan 4 at 19:28
1
1
@scsimon: I don't see CXPACKET when i run
sp_whoisactive,i see only CXCONSUMER.I will check the links.– user9516827
Jan 4 at 19:32
@scsimon: I don't see CXPACKET when i run
sp_whoisactive,i see only CXCONSUMER.I will check the links.– user9516827
Jan 4 at 19:32
add a comment |
1 Answer
1
active
oldest
votes
Check out this post from Erik Darling: CXCONSUMER Is Harmless? Not So Fast, Tiger
That shows a really extreme example of a problem query where CXCONUSMER is the highest wait. So while the Microsoft recommendations indicate it's harmless, it definitely can be a sign of other problems.
Based on that, and your screenshot, it's quite possible that you're running into issues with skewed parallelism. You can find some great info about skewed parallelism from Paul Randal: More on CXPACKET Waits: Skewed Parallelism
In theory, waits due to skewed parallelism should be surfaced as CXPACKET waits. This doesn't appear to always be the case in practice at this time though.
Without the query text, and especially an actual execution plan, we can only guess at what might be causing the CXCONSUMER waits for your scenario. But hopefully this helps gives you a direction to look in.
If you edit your question to include the execution plan and query text (and relevant table / index definitions), we can be more help in tracking down the root cause.
answered Jan 4 at 19:30
Josh DarnellJosh Darnell
7,84022243
add a comment |
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1 Answer
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votes
Check out this post from Erik Darling: CXCONSUMER Is Harmless? Not So Fast, Tiger
That shows a really extreme example of a problem query where CXCONUSMER is the highest wait. So while the Microsoft recommendations indicate it's harmless, it definitely can be a sign of other problems.
Based on that, and your screenshot, it's quite possible that you're running into issues with skewed parallelism. You can find some great info about skewed parallelism from Paul Randal: More on CXPACKET Waits: Skewed Parallelism
In theory, waits due to skewed parallelism should be surfaced as CXPACKET waits. This doesn't appear to always be the case in practice at this time though.
Without the query text, and especially an actual execution plan, we can only guess at what might be causing the CXCONSUMER waits for your scenario. But hopefully this helps gives you a direction to look in.
If you edit your question to include the execution plan and query text (and relevant table / index definitions), we can be more help in tracking down the root cause.
answered Jan 4 at 19:30
Josh DarnellJosh Darnell
7,84022243
add a comment |
Check out this post from Erik Darling: CXCONSUMER Is Harmless? Not So Fast, Tiger
That shows a really extreme example of a problem query where CXCONUSMER is the highest wait. So while the Microsoft recommendations indicate it's harmless, it definitely can be a sign of other problems.
Based on that, and your screenshot, it's quite possible that you're running into issues with skewed parallelism. You can find some great info about skewed parallelism from Paul Randal: More on CXPACKET Waits: Skewed Parallelism
In theory, waits due to skewed parallelism should be surfaced as CXPACKET waits. This doesn't appear to always be the case in practice at this time though.
Without the query text, and especially an actual execution plan, we can only guess at what might be causing the CXCONSUMER waits for your scenario. But hopefully this helps gives you a direction to look in.
If you edit your question to include the execution plan and query text (and relevant table / index definitions), we can be more help in tracking down the root cause.
answered Jan 4 at 19:30
Josh DarnellJosh Darnell
7,84022243
add a comment |
Check out this post from Erik Darling: CXCONSUMER Is Harmless? Not So Fast, Tiger
That shows a really extreme example of a problem query where CXCONUSMER is the highest wait. So while the Microsoft recommendations indicate it's harmless, it definitely can be a sign of other problems.
Based on that, and your screenshot, it's quite possible that you're running into issues with skewed parallelism. You can find some great info about skewed parallelism from Paul Randal: More on CXPACKET Waits: Skewed Parallelism
In theory, waits due to skewed parallelism should be surfaced as CXPACKET waits. This doesn't appear to always be the case in practice at this time though.
Without the query text, and especially an actual execution plan, we can only guess at what might be causing the CXCONSUMER waits for your scenario. But hopefully this helps gives you a direction to look in.
If you edit your question to include the execution plan and query text (and relevant table / index definitions), we can be more help in tracking down the root cause.
answered Jan 4 at 19:30
Josh DarnellJosh Darnell
7,84022243
Check out this post from Erik Darling: CXCONSUMER Is Harmless? Not So Fast, Tiger
That shows a really extreme example of a problem query where CXCONUSMER is the highest wait. So while the Microsoft recommendations indicate it's harmless, it definitely can be a sign of other problems.
Based on that, and your screenshot, it's quite possible that you're running into issues with skewed parallelism. You can find some great info about skewed parallelism from Paul Randal: More on CXPACKET Waits: Skewed Parallelism
In theory, waits due to skewed parallelism should be surfaced as CXPACKET waits. This doesn't appear to always be the case in practice at this time though.
Without the query text, and especially an actual execution plan, we can only guess at what might be causing the CXCONSUMER waits for your scenario. But hopefully this helps gives you a direction to look in.
If you edit your question to include the execution plan and query text (and relevant table / index definitions), we can be more help in tracking down the root cause.
answered Jan 4 at 19:30
Josh DarnellJosh Darnell
7,84022243
edited Mar 8 at 16:51
answered Jan 4 at 19:30
Josh DarnellJosh Darnell
7,84022243
answered Jan 4 at 19:30
Josh DarnellJosh Darnell
7,84022243
answered Jan 4 at 19:30
Josh DarnellJosh Darnell
7,84022243
7,84022243
add a comment |
add a comment |
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1
have you tried brentozar.com/blitz ? It's very usefull and have a part to identify waits (brentozar.com/sql/wait-stats )
– Danielle Paquette-Harvey
Jan 4 at 19:17
1
Check out what Paul Randal says about that wait. He also has some steps on working on CXPACKET as does Brent Ozar but as you said, you don't see this wait type.
– scsimon
Jan 4 at 19:28
1
@scsimon: I don't see CXPACKET when i run
sp_whoisactive,i see only CXCONSUMER.I will check the links.– user9516827
Jan 4 at 19:32