Azure SQL - High CPU usage - Wait type: SOS Wait Dispatch

Question

Azure SQL - High CPU usage - Wait type: SOS Wait Dispatch

Alex 0

I have a current Azure SQL database running high CPU utilization. running sp_who2 shows task: SUSPENDED DB000013 programname: tdService. Can this be turned off or adjusted.

maxdop adjusted
index fragmentation - resolved

Erland Sommarskog 121.3K Reputation points MVP Volunteer Moderator

2025-06-11T21:53:14.77+00:00

Sai's answer is certainly confused. The actual wait that Alex is seeing is SOS_WAIT_DISPATCHER, which you can read about in Paul Randall's Waitopedia here: https://www.sqlskills.com/help/waits/sos_work_dispatcher/. In short, the task is waiting for work to do and is idle. This is a benign wait can be ignored. So there is no need to worry about that particular one.

SOS_SCHEDULER_YIELD, that Sai mentions, on the other hand is not a benign wait. This wait occurs when a process yields voluntarily, which typically happens every 4 ms. If no other process is waiting to run, the process will resume executing. Else it will be stuck in this wait until the CPU is available.

Alex said that there is high CPU, so maybe there are high SOS_SCHEDULER_YIELD waits. But since we don't have more information, it is difficult to say what to do.
Sai Raghunadh M 4,120 Reputation points Microsoft External Staff Moderator

2025-06-12T20:26:24.5533333+00:00

Hi @ Alex

We haven’t heard from you on the last response and was just checking back to see if you have a resolution yet. In case if you have any resolution, please do share that same with the community as it can be helpful to others. Otherwise, will respond with more details and we will try to help.
Sai Raghunadh M 4,120 Reputation points Microsoft External Staff Moderator

2025-06-13T19:14:38.3633333+00:00

Hi @ Alex

We haven’t heard from you on the last response and was just checking back to see if you have a resolution yet. In case if you have any resolution, please do share that same with the community as it can be helpful to others. Otherwise, will respond with more details and we will try to help.

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Erland Sommarskog 121.3K Reputation points MVP Volunteer Moderator

2025-06-11T21:53:14.77+00:00

Sai's answer is certainly confused. The actual wait that Alex is seeing is SOS_WAIT_DISPATCHER, which you can read about in Paul Randall's Waitopedia here: https://www.sqlskills.com/help/waits/sos_work_dispatcher/. In short, the task is waiting for work to do and is idle. This is a benign wait can be ignored. So there is no need to worry about that particular one.

SOS_SCHEDULER_YIELD, that Sai mentions, on the other hand is not a benign wait. This wait occurs when a process yields voluntarily, which typically happens every 4 ms. If no other process is waiting to run, the process will resume executing. Else it will be stuck in this wait until the CPU is available.

Alex said that there is high CPU, so maybe there are high SOS_SCHEDULER_YIELD waits. But since we don't have more information, it is difficult to say what to do.
Sai Raghunadh M 4,120 Reputation points Microsoft External Staff Moderator

2025-06-12T20:26:24.5533333+00:00

Hi @ Alex

We haven’t heard from you on the last response and was just checking back to see if you have a resolution yet. In case if you have any resolution, please do share that same with the community as it can be helpful to others. Otherwise, will respond with more details and we will try to help.
Sai Raghunadh M 4,120 Reputation points Microsoft External Staff Moderator

2025-06-13T19:14:38.3633333+00:00

Hi @ Alex

We haven’t heard from you on the last response and was just checking back to see if you have a resolution yet. In case if you have any resolution, please do share that same with the community as it can be helpful to others. Otherwise, will respond with more details and we will try to help.

Answer 1

Hi @ Alex

Thank you for reaching out regarding the high CPU utilization in your Azure SQL database. Upon reviewing your system, we've identified that the tdService task is in a suspended state, and the SOS_SCHEDULER_YIELD wait type is prevalent.

A query enters a suspended state when it requires access to a resource that is currently unavailable. This could be due to logical reasons, such as waiting for a locked row, or physical reasons, like awaiting a memory data page. The query will resume execution once the requested resource becomes accessible.

High disk I/O indicates that a significant number of data pages need to be read from or written to disk to complete the operation.

Hope this helps. Do let us know if you any further queries.

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Azure SQL - High CPU usage - Wait type: SOS Wait Dispatch

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