Slow initial response from ASP.NET CORE WEBAPI service in Azure - Always On is True already

Question

I have an ASP.NET WEBAPI service running in Azure using Azure Active Directory and Azure SQL Server. I have gone into Azure App Services settings and turned on Always On, but I am sure the WEBAPI is unloading.

For testing I have a set of calls that usually take 4-5 seconds. Sometimes the calls take over 30 seconds.

Other than this occasional slow response, there are no issues.

The WEBAPI service has no viewable pages. API controllers only.

Probably not relevant, but I also use EF for data access. I also use CORS.

Here are my Azure App Settings:

[
  {
    "name": "ASPNETCORE_ENVIRONMENT",
    "value": "Development",
    "slotSetting": true
  },
  {
    "name": "BasePath",
    "value": "*****************************",
    "slotSetting": true
  },
  {
    "name": "WEBSITE_HTTPLOGGING_RETENTION_DAYS",
    "value": "7",
    "slotSetting": false
  },
  {
    "name": "WEBSITE_RUN_FROM_PACKAGE",
    "value": "1",
    "slotSetting": false
  }
]

Here is the Azure General Settings:

Here is most of my StartUp.cs file:

public void ConfigureServices(IServiceCollection services)
{
    services.AddDbContext<DatabaseContext>(options =>
        options.UseSqlServer(
            Configuration.GetConnectionString("DefaultConnection"), o =>
            {
                o.EnableRetryOnFailure();
            })
        .ConfigureWarnings(warnings => warnings.Ignore(Microsoft.EntityFrameworkCore.Diagnostics.CoreEventId.ContextInitialized))
        .EnableSensitiveDataLogging(true));

    services
        .AddAuthentication("Azure")
        .AddPolicyScheme("Azure", "Authorize AzureAd or AzureAdBearer", options =>
        {
            options.ForwardDefaultSelector = context =>
            {
                var authHeader = context.Request.Headers["Authorization"].FirstOrDefault();
                if (authHeader?.StartsWith("Bearer") == true)
                {
                    return JwtBearerDefaults.AuthenticationScheme;
                }
                return AzureADDefaults.AuthenticationScheme;
            };
        })
        .AddJwtBearer(opt =>
        {
            opt.Audience = Configuration["AAD:ResourceId"];
            opt.Authority = $"{Configuration["AAD:Instance"]}{Configuration["AAD:TenantId"]}";
        })
        .AddAzureAD(options => Configuration.Bind("AzureAd", options));


    var origins = Configuration.GetSection("AppSettings:AllowedOrigins").Value.Split(",");
    services.AddCors(o => o.AddPolicy(specificOrigins, builder =>
    {
        builder.WithOrigins(origins)
               .AllowAnyMethod()
               .AllowAnyHeader()
               .AllowCredentials()
               .SetIsOriginAllowed((host) => true);
    }));

    services.Configure<CookiePolicyOptions>(options =>
    {
        options.MinimumSameSitePolicy = SameSiteMode.Strict;
        options.HttpOnly = Microsoft.AspNetCore.CookiePolicy.HttpOnlyPolicy.Always;
        options.Secure = CookieSecurePolicy.Always;
    });
    services.AddResponseCaching();

    services.AddControllers();

    services.AddSingleton<IHttpContextAccessor, HttpContextAccessor>();
    services.AddScoped<LogUserActivity>();
    services.AddSession();
    services.AddHttpContextAccessor();
    services.AddAutoMapper();
}

// This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
public void Configure(IApplicationBuilder app, ILoggerFactory loggerFactory)
{
    loggerFactory.AddSerilog();
    if (_currentEnvironment.IsDevelopment() || _currentEnvironment.IsEnvironment("LOCAL"))
    {
        app.UseDeveloperExceptionPage();
    }
    else
    {
        app.UseExceptionHandler("/Home/Error");
        app.UseHsts();
    }
    app.UseCors(specificOrigins);
    app.UseHttpsRedirection();
    app.UseSession();
    app.UseStaticFiles();

    app.UseRouting();

    app.UseResponseCaching();

    app.UseCookiePolicy();
    app.UseAuthentication();
    app.UseAuthorization();

    app.UseEndpoints(endpoints =>
    {
        endpoints.MapControllers();
        endpoints.MapDefaultControllerRoute();
    });
}

If my solution helps you, could you please mark my answer as [accepted](https://meta.stackexchange.com/questions/5234/how-does-accepting-an-answer-work), tks~ — Jason Pan, Dec 30 '20 at 02:02

score 1 · Answer 1 · answered Dec 15 '20 at 02:04

1

The answer to this question should be the process of testing.

According to the official explanation, we can see.

Test Steps

Create a test api, like below for test.

public string test() {
    return "I'm test api.";
}

Insert code that calculates the execution time of each step or line of code

Eg: Using Stopwatch in C#

The Reason

The official always on should be no problem. It is recommended to pass the test code, and test each step takes a long time.

Then the tested api is used to test whether the phenomenon you mentioned will still occur when this simple code is executed under the same conditions.

The possible cause of the problem is to connect to the database to execute SQL, or other business takes a long time, or other errors. Record the time-consuming time or view it through ILogger output.

answered Dec 15 '20 at 02:04

Jason Pan

15,263
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I will try your suggestions. – Bobby Ortiz Dec 15 '20 at 13:22
I am still testing. Your comment helped so, but I am still digging. – Bobby Ortiz Dec 18 '20 at 18:35
@BobbyOrtiz have you found sth.? Having the same issue here... – c_ph_r Aug 02 '22 at 08:59
Sorry, nothing I have tried fixed the issue – Bobby Ortiz Aug 15 '22 at 20:44

Slow initial response from ASP.NET CORE WEBAPI service in Azure - Always On is True already

1 Answers1

The answer to this question should be the process of testing.

Test Steps

The Reason