Identify Query Waiting on resources
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
334110
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
334110
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
334110
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
334110
asked Jan 4 at 19:14
user9516827user9516827
334110
asked Jan 4 at 19:14
user9516827user9516827
334110
asked Jan 4 at 19:14
user9516827user9516827
334110
asked Jan 4 at 19:14
user9516827user9516827
334110
334110
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
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.
edited Jan 4 at 22:01
Erik Darling
21.2k1264104
answered Jan 4 at 19:30
jadarnel27jadarnel27
3,9971330
1
But if skewed parallelism is the issue, it should be surfacing asCXPACKETand notCXCONSUMER- that was the whole point of the new wait type.
– Aaron Bertrand♦
Jan 4 at 19:40
1
@AaronBertrand Maybe there is something wrong with the implementation of the wait then? I'm not sure. Looking at Erik's blog post, check out the image near the end. There's definitely massive skew. But maybe that's not strictly the problem.
– jadarnel27
Jan 4 at 19:55
I know, I'm agreeing, it should be surfaced differently. But there may be more to this scenario (and Erik's). The fact thatCXPACKETis high in wait stats but isn't being "caught" suggests there is some timing issue or something else going on.
– Aaron Bertrand♦
Jan 4 at 20:42
@AaronBertrand Oh! Sorry, I'm following you now.
– jadarnel27
Jan 4 at 21:00
add a comment |
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1 Answer
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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
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.
edited Jan 4 at 22:01
Erik Darling
21.2k1264104
answered Jan 4 at 19:30
jadarnel27jadarnel27
3,9971330
1
But if skewed parallelism is the issue, it should be surfacing asCXPACKETand notCXCONSUMER- that was the whole point of the new wait type.
– Aaron Bertrand♦
Jan 4 at 19:40
1
@AaronBertrand Maybe there is something wrong with the implementation of the wait then? I'm not sure. Looking at Erik's blog post, check out the image near the end. There's definitely massive skew. But maybe that's not strictly the problem.
– jadarnel27
Jan 4 at 19:55
I know, I'm agreeing, it should be surfaced differently. But there may be more to this scenario (and Erik's). The fact thatCXPACKETis high in wait stats but isn't being "caught" suggests there is some timing issue or something else going on.
– Aaron Bertrand♦
Jan 4 at 20:42
@AaronBertrand Oh! Sorry, I'm following you now.
– jadarnel27
Jan 4 at 21:00
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
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.
edited Jan 4 at 22:01
Erik Darling
21.2k1264104
answered Jan 4 at 19:30
jadarnel27jadarnel27
3,9971330
1
But if skewed parallelism is the issue, it should be surfacing asCXPACKETand notCXCONSUMER- that was the whole point of the new wait type.
– Aaron Bertrand♦
Jan 4 at 19:40
1
@AaronBertrand Maybe there is something wrong with the implementation of the wait then? I'm not sure. Looking at Erik's blog post, check out the image near the end. There's definitely massive skew. But maybe that's not strictly the problem.
– jadarnel27
Jan 4 at 19:55
I know, I'm agreeing, it should be surfaced differently. But there may be more to this scenario (and Erik's). The fact thatCXPACKETis high in wait stats but isn't being "caught" suggests there is some timing issue or something else going on.
– Aaron Bertrand♦
Jan 4 at 20:42
@AaronBertrand Oh! Sorry, I'm following you now.
– jadarnel27
Jan 4 at 21:00
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
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.
edited Jan 4 at 22:01
Erik Darling
21.2k1264104
answered Jan 4 at 19:30
jadarnel27jadarnel27
3,9971330
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
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.
edited Jan 4 at 22:01
Erik Darling
21.2k1264104
answered Jan 4 at 19:30
jadarnel27jadarnel27
3,9971330
edited Jan 4 at 22:01
Erik Darling
21.2k1264104
edited Jan 4 at 22:01
Erik Darling
21.2k1264104
edited Jan 4 at 22:01
Erik Darling
21.2k1264104
21.2k1264104
answered Jan 4 at 19:30
jadarnel27jadarnel27
3,9971330
answered Jan 4 at 19:30
jadarnel27jadarnel27
3,9971330
answered Jan 4 at 19:30
jadarnel27jadarnel27
3,9971330
3,9971330
1
But if skewed parallelism is the issue, it should be surfacing asCXPACKETand notCXCONSUMER- that was the whole point of the new wait type.
– Aaron Bertrand♦
Jan 4 at 19:40
1
@AaronBertrand Maybe there is something wrong with the implementation of the wait then? I'm not sure. Looking at Erik's blog post, check out the image near the end. There's definitely massive skew. But maybe that's not strictly the problem.
– jadarnel27
Jan 4 at 19:55
I know, I'm agreeing, it should be surfaced differently. But there may be more to this scenario (and Erik's). The fact thatCXPACKETis high in wait stats but isn't being "caught" suggests there is some timing issue or something else going on.
– Aaron Bertrand♦
Jan 4 at 20:42
@AaronBertrand Oh! Sorry, I'm following you now.
– jadarnel27
Jan 4 at 21:00
add a comment |
1
But if skewed parallelism is the issue, it should be surfacing asCXPACKETand notCXCONSUMER- that was the whole point of the new wait type.
– Aaron Bertrand♦
Jan 4 at 19:40
1
@AaronBertrand Maybe there is something wrong with the implementation of the wait then? I'm not sure. Looking at Erik's blog post, check out the image near the end. There's definitely massive skew. But maybe that's not strictly the problem.
– jadarnel27
Jan 4 at 19:55
I know, I'm agreeing, it should be surfaced differently. But there may be more to this scenario (and Erik's). The fact thatCXPACKETis high in wait stats but isn't being "caught" suggests there is some timing issue or something else going on.
– Aaron Bertrand♦
Jan 4 at 20:42
@AaronBertrand Oh! Sorry, I'm following you now.
– jadarnel27
Jan 4 at 21:00
1
1
But if skewed parallelism is the issue, it should be surfacing as
CXPACKET and not CXCONSUMER - that was the whole point of the new wait type.– Aaron Bertrand♦
Jan 4 at 19:40
But if skewed parallelism is the issue, it should be surfacing as
CXPACKET and not CXCONSUMER - that was the whole point of the new wait type.– Aaron Bertrand♦
Jan 4 at 19:40
1
1
@AaronBertrand Maybe there is something wrong with the implementation of the wait then? I'm not sure. Looking at Erik's blog post, check out the image near the end. There's definitely massive skew. But maybe that's not strictly the problem.
– jadarnel27
Jan 4 at 19:55
@AaronBertrand Maybe there is something wrong with the implementation of the wait then? I'm not sure. Looking at Erik's blog post, check out the image near the end. There's definitely massive skew. But maybe that's not strictly the problem.
– jadarnel27
Jan 4 at 19:55
I know, I'm agreeing, it should be surfaced differently. But there may be more to this scenario (and Erik's). The fact that
CXPACKET is high in wait stats but isn't being "caught" suggests there is some timing issue or something else going on.– Aaron Bertrand♦
Jan 4 at 20:42
I know, I'm agreeing, it should be surfaced differently. But there may be more to this scenario (and Erik's). The fact that
CXPACKET is high in wait stats but isn't being "caught" suggests there is some timing issue or something else going on.– Aaron Bertrand♦
Jan 4 at 20:42
@AaronBertrand Oh! Sorry, I'm following you now.
– jadarnel27
Jan 4 at 21:00
@AaronBertrand Oh! Sorry, I'm following you now.
– jadarnel27
Jan 4 at 21:00
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