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Hi,
We are facing 504 Gateway timeout errors frequently. When this happens the website also is unresponsive for a couple of minutes.
We could reproduce this even on our lower environments by hitting an api consecutively 2-3 times. While the first time the response comes up the other times it waits for a longer duration and gives 504 timeout error. When this happens or website also does not work.
We are unable to find any traces of the later requests in access.log so the application issue is out of question. We saw if there are any db locks which would have caused by the earlier request and that is also not the case. Infact the first request does no processing at all it just hits and gives a response back immediately.
The production webapp is on App service (Both front end and backend) while the lower environments (dev) are on azurestaticwebapp for frontend and app service for backend.
Any pointers on how to trouble shoot this would really help.
Thanks,
Kotesh
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@Koteswara Pentakota , Apologies you're experiencing timeout and performance issues. To better assist you on this, kindly share the following info:
Were there any changes prior to this issue or it’s always been this way since the WebApp deployment?
Do you have an Application Gateway (AGw) in between this App Service WebApp?
What App Service Plan (ASP)? If you’re using, AGw, is it AGw v1 or v2 SKU?
Just as quick test, if you’re running a lower ASP tier, scale-up your ASP to Standard tier and then test your WebApp for some time. After the test, you may lower your ASP tier, as necessary.
If you haven’t done this already, kindly review these logs to further isolate the issue:
Application logging, Web Server logging, Detailed Error Messages --Kindly checkout the process here - >>Enable diagnostics logging for apps in Azure App Service
Additionally:
Keep-Alive timeout governs how long the Application Gateway will wait for a client to send another HTTP request on a persistent connection before reusing it or closing it. TCP idle timeout governs how long a TCP connection is kept open in case of no activity.
See this doc - what-are-the-settings-for-keep-alive-timeout-and-tcp-idle-timeout
Kindly let us know how it goes, we will need additional information to perform deeper investigation on this. I'll follow-up with you further.
Hi @ajkuma
We are not using any Application Gateway. We are using App Service Plan with S3 Tier.
The performance issue was in application loading. The website does not load when this timeout happens, that is why had to mix both of them.
Logging is enabled but not sure on the keep alive timeout. Will check and come back.
We are unable to understand on why the timeout is happening only when we do service calls repeatedly. This timeout issue is there since a couple of weeks and G7CR team could not get any resolution to this.
Thanks,
Kotesh
To benefit the community: We have been following-up on this offline/privately, based on the final outcome, we will update this thread.
For the community: feel free to share your insights or outcomes of handling a similar experience.
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@ajkuma - I am facing a similar issue, across many App services. The difference is we are using App Gateway before that and can see backend as Unhealthy whereas the App service in the backend pool is running fine. It happens intermittently and difficult to reproduce.
We are using App Service Environment v2 and there are 6 App service Plans running within it. Don't understand what is causing this. Also, there are no deployment to these App services happening during that period when this occurs.
Always On and rest of the setting looks fine anyways. Kudu logs doesn't say much in this case.
Any pointer?
Rishi, Apologies for the delay and any inconvenience with this! I understand you have mentioned that you have already checked the logs. You have stated "facing a similar issue, across many App services", are those on same region? What was the outcome of App Service diagnostics? We will need additional info about the resources to better understand the issue.
Note: Please do not share your PII data on public forum/post.
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How was this resolved?
Apologies for the delay!
Sharing info from our offline discussion. Based on the analysis (of the environment), some recommendations for implementation were shared:
• Observed - Health check was configured to health check for URI “/login” which is not recommended. To counter that, use any API which doesn’t have huge load because health check itself will send requests to the application.