Application pool requested a recycle because it reached its virtual memory limit

Question

I hosted a web application on a (Live server) shared hosting, and did not get any issue until today when I decided to test-run it. I registered and logged in the web application with the test login details; I was redirected to the dashboard, but after some seconds I was redirected back to the login page (I got logged out). I don't know how this happened, it quickly logs me out and redirects me to login page. After this persisted, I contacted my hosting company then I was told that I maxed out my resource which was causing the issue. A worker process with id serving application pool 'website domain name(domain)(4.0)(pool) has requested a recycle because it reached its virtual memory limit.

To be honest, I don't know how this happened because the application has been on a live server for months without this issue. However, I will like to know if this can be resolved and also prevent a re-occurrence?

Please can anyone help me with details of how to resolve this?

Could it be that there is something I did or didn't do in my web.config file?

<configuration>
  <connectionStrings>
    <add name="ConString" connectionString="My Connection String goes here"/>
  </connectionStrings>
  <appSettings>
    <add key="ValidationSettings:UnobtrusiveValidationMode" value="None" />
  </appSettings>
  <system.web>
  <sessionState timeout="30"></sessionState>
    <trust level="Full" />
    <authentication mode="Forms">
      <forms timeout="30" cookieless="UseCookies" loginUrl="https://mywebsite.com/login" defaultUrl="https://mywebsite.com/home" slidingExpiration="true" />
    </authentication>
    <authorization>
      <deny users="?" />
    </authorization>
    <compilation debug="true" targetFramework="4.7.2" />
    <httpRuntime targetFramework="4.7.2" maxRequestLength="3145728" />
    <customErrors mode="Off" />
    <pages enableEventValidation="false">
      <controls>
        <add tagPrefix="ajaxToolkit" assembly="AjaxControlToolkit" namespace="AjaxControlToolkit" />
      </controls>
    </pages>
	<machineKey validationKey="***" decryptionKey="***" validation="SHA1" decryption="AES" />
  </system.web>
  <system.webServer>
    <defaultDocument enabled="true">
      <files>
        <clear />
        <add value="Default.aspx" />
      </files>
    </defaultDocument>
  </system.webServer>
  <system.web.extensions>
    <scripting>
      <webServices>
        <jsonSerialization maxJsonLength="2147483644"></jsonSerialization>
      </webServices>
    </scripting>
  </system.web.extensions>
  <runtime>
    <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
      <dependentAssembly>
        <assemblyIdentity name="System.Runtime.CompilerServices.Unsafe" publicKeyToken="***" culture="neutral" />
        <bindingRedirect oldVersion="0.0.0.0-6.0.0.0" newVersion="6.0.0.0" />
      </dependentAssembly>
      <dependentAssembly>
        <assemblyIdentity name="BouncyCastle.Crypto" publicKeyToken="0e99375e54769942" culture="neutral" />
        <bindingRedirect oldVersion="0.0.0.0-1.9.0.0" newVersion="1.9.0.0" />
      </dependentAssembly>
      <dependentAssembly>
        <assemblyIdentity name="Microsoft.Extensions.DependencyInjection.Abstractions" publicKeyToken="***" culture="neutral" />
        <bindingRedirect oldVersion="0.0.0.0-7.0.0.0" newVersion="7.0.0.0" />
      </dependentAssembly>
      <dependentAssembly>
        <assemblyIdentity name="Microsoft.Extensions.DependencyInjection" publicKeyToken="***" culture="neutral" />
        <bindingRedirect oldVersion="0.0.0.0-7.0.0.0" newVersion="7.0.0.0" />
      </dependentAssembly>
      <dependentAssembly>
        <assemblyIdentity name="Microsoft.Extensions.Logging.Abstractions" publicKeyToken="***" culture="neutral" />
        <bindingRedirect oldVersion="0.0.0.0-7.0.0.0" newVersion="7.0.0.0" />
      </dependentAssembly>
      <dependentAssembly>
        <assemblyIdentity name="Microsoft.Extensions.Logging" publicKeyToken="***" culture="neutral" />
        <bindingRedirect oldVersion="0.0.0.0-7.0.0.0" newVersion="7.0.0.0" />
      </dependentAssembly>
    </assemblyBinding>
  </runtime>
  <system.codedom></system.codedom>
</configuration>

I also have this page load event on every page on the application

protected void Page_Load(object sender, EventArgs e)
        {
            if (this.Page.User.Identity.IsAuthenticated && Session["user"] != null)
            {
                labelid.Text = Session["user"].ToString();
                Showdata1();
            }
            else
            {
                Response.Redirect("login");
            }
            Response.Cache.SetCacheability(HttpCacheability.NoCache);
            Response.Cache.SetExpires(DateTime.Now.AddSeconds(-1));
            Response.Cache.SetNoStore();
            Response.AppendHeader("Pragma", "no-cache");
        }

I have also been thinking if it came as a result of using 3rd party API like ip2location to get user's local time zone

private void LastLogin()
        {
            string connectionString = ConfigurationManager.ConnectionStrings["ConString"].ConnectionString;
            using (SqlConnection con = new SqlConnection(connectionString))
            {
                using (SqlCommand cmd = new SqlCommand("SELECT LastLogin FROM UserTable WHERE id = @id", con))
                {
                    cmd.Parameters.AddWithValue("@id", Session["user"]);
                    con.Open();
                    DateTime time1 = Convert.ToDateTime(Session["LastLogin"]);
                    TimeZoneInfo serverTimeZone = TimeZoneInfo.FindSystemTimeZoneById("GMT Standard Time");
                    TimeZoneInfo userTimeZone = TimeZoneInfo.FindSystemTimeZoneById(GetTimeZoneNameByOffsetTime(this.GetLocation().time_zone.Replace("+", "")));
                    DateTime userLocalTime = TimeZoneInfo.ConvertTime(time1, serverTimeZone, userTimeZone);
                    Timelbl.Text = userLocalTime.ToString("dddd, MMMM d, yyyy h:mm tt");
                }
            }
        }

Answer 1

1. I hope recycling of the dedicated IIS Application pool for websites will not cause any issues on my application ?

Recycling the application pool clears Session and creates a new encryption key (default setting). A new encryption key invalidates any current authenticated users.

2. Will this issue re-occur in the future?

If there is a memory leak then yes it will happen again. A memory leak is code that stores information in volatile memory and never releases the memory. It could be code that is slowly using up memory over time, a process that stores a lot of data in memory, or a little of both.

3. And will I continue to do this each time this happens?

Probably, it depends on the cause. Finding and fixing the bug is a better solution.

Answer 2

I think I know why my virtual memory was used up by my application. I left a whole lot of Database connections open in my code. I left about 60-70% connections open on each page and did not close them. That's why my application used up its memory. Those open connections were consuming resources on the server.