MQTT socket going into close wait state

Question

MQTT socket going into close wait state

Anoop Chandran 25

Hi,

I am currently working on the iot-middleware-freertos-samples to implement MQTT.

After establishing the MQTTS connection and subscribing to the required topics I am trying to send telemetry data to the IoT hub but after some time the MQTT socket is going to a close wait state.

I am using the API " AzureIoTHubClient_SendTelemetry" to send the payload.

After sending the telemetry data I am also calling the function "AzureIoTHubClient_ProcessLoop" for receiving any responses.

Can you please tell me how I can avoid this close wait state?

I have set the keep-alive time out as 5 min and Iam sending data every 1min.

Regards

Anoop

Anoop Chandran 25 Reputation points

2023-06-08T10:52:08.6733333+00:00

Hi @LeelaRajeshSayana-MSFT ,

Thanks for the response I have changed the "sampleazureiotPROCESS_LOOP_TIMEOUT_MS" to 1000 from 500 now that the connection is stable for a long time.

Also, Can you please help me with where can I see the Azure logs for errors or warnings and which warnings/ errors can cause this close wait state to the MQTT Socket?

Regards

Anoop
LeelaRajeshSayana-MSFT 17,871 Reputation points Moderator

2023-06-08T16:37:14.47+00:00

Hi @Anoop Chandran Thank you for testing the proposed suggestion. I am glad to know that the suggestion helped with stabilizing the connection.

You may follow the steps in the article Collect logs for connections and device telemetry to capture logs from IoT Hub. Please make sure to check the Connections category as you set up the Diagnostic setting to capture any connection related logs to the IoT Hub.

I appreciate it if you can click Accept Answer and Yes for the answer provided below. Doing so would help other community members with similar issue identify the solution. I highly appreciate your contribution to the community.

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Anoop Chandran 25 Reputation points

2023-06-08T10:52:08.6733333+00:00

Hi @LeelaRajeshSayana-MSFT ,

Thanks for the response I have changed the "sampleazureiotPROCESS_LOOP_TIMEOUT_MS" to 1000 from 500 now that the connection is stable for a long time.

Also, Can you please help me with where can I see the Azure logs for errors or warnings and which warnings/ errors can cause this close wait state to the MQTT Socket?

Regards

Anoop
LeelaRajeshSayana-MSFT 17,871 Reputation points Moderator

2023-06-08T16:37:14.47+00:00

Hi @Anoop Chandran Thank you for testing the proposed suggestion. I am glad to know that the suggestion helped with stabilizing the connection.

You may follow the steps in the article Collect logs for connections and device telemetry to capture logs from IoT Hub. Please make sure to check the Connections category as you set up the Diagnostic setting to capture any connection related logs to the IoT Hub.

I appreciate it if you can click Accept Answer and Yes for the answer provided below. Doing so would help other community members with similar issue identify the solution. I highly appreciate your contribution to the community.

Answer 1

LeelaRajeshSayana-MSFT 17,871 Moderator

Hi @Anoop Chandran Greetings! Welcome to Microsoft Q&A forum. Thank you for posting the question here. The close wait state indicates that the socket is waiting for the remote end to close the connection. It is possible that the Azure IoT Hub is not closing the connection after receiving the telemetry data.

I appreciate it if you can check the Azure IoT Hub logs to see if there are any errors or warnings related to the connection. Also, please try increasing the sampleazureiotPROCESS_LOOP_TIMEOUT_MS value to give more time for the connection to close.

Let me know if this helps.

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