Question

I run a website with IIS 7.5 in classic ASP with an isolated Application Pool (ApplicationPoolIdentity). Inside this website I also run unmanaged code (wkhtmltopdf.exe) thru “WScript.Shell” object run method. After that I stream the result file as pdf

set wshell = CreateObject("WScript.Shell") 
wshell.run wkhtmltopdf.exe  http://www.mypagehanging.com c:\myfile.pdf", 0, TRUE 
set wshell = nothing 

Everything works fine but sometimes my Website Hang. It’s completely stuck. The wktmltopdf.exe running under the identity of the app pool (iis apppool\myapp) hangs.

This causes my all website to hang because i run the program with option bWaitOnReturn to true.

I cannot set this option to false because I must wait for the script to execute completely before streaming the pdf.

Couldn’t find any timeout option to give to wkhtmltopdf. Couldn’t understand why wkhtmltopdf was hanging. But it’s probably caused by the website I’m trying to render and not wkhtmltopdf.

Any suggestions ?

Answer 1

I’ve addressed this problem by killing the process if it takes an unusual amount of time to run.

here is my code should it be helpful to someone.

In the asp file

'Run this programm that will kill pdf generation if it hangs-execute for more than 10seconds
wshell.run "KillProcess.exe -p wkhtmltopdf -t 10000",0,FALSE 
'Launch pdf generation with bwaitonreturn true 
wshell.run wkhtmltopdf.exe  http://www.mypagehanging.com  c:\inetpub\wwwroot\myfile.pdf", 0, TRUE 

'Stream the pdf ...

Code source for the KillProcess.exe

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
using System.Diagnostics;
using CommandLine; //http://commandline.codeplex.com
using CommandLine.Text; //http://commandline.codeplex.com

namespace KillProcess
{
    class Program
    {
        static void Main(string[] args)
        {
            var options = new Options();
            ICommandLineParser parser = new CommandLineParser();

            if (parser.ParseArguments(args, options))
            {
                double maxWaitTime = options.time; //ms
                string processName = options.process;
                bool exit;
                do
                {
                    exit = true;
                    foreach (Process p in GetProcesses(processName))
                    {
                        exit = false;
                        try
                        {
                            if (p.StartTime.AddMilliseconds(maxWaitTime) < DateTime.Now)
                            {
                                p.Kill();
                                Console.WriteLine("Killed Process: {0} ID: {1} started at {2} after {3}ms of execution time", p.ProcessName, p.Id, p.StartTime, options.time);
                            }
                        }
                        catch (Exception e)
                        {
                            Console.WriteLine(e.Message);
                        }
                    }
                    Thread.Sleep(100);
                } while (!exit);
                return;
            }
            else
            {
                Console.WriteLine(options.GetUsage());
                return;
            }
        }

        static IEnumerable<Process> GetProcesses(string processName)
        {
            var processes = from p in Process.GetProcesses()
                            where p.ProcessName == processName
                            orderby p.ProcessName
                            select p;
            return processes;
        }

        class Options : CommandLineOptionsBase
        {
            [Option("p", "process", Required = true, HelpText = "Name of the process-es to kill after some execution time (Warning ! This will kill all the processes that match the name !)")]
            public string process { get; set; }

            [Option("t", "time", Required = true, HelpText = "Maximum execution time allowed for the process to run. If the process has run for more than this amount of time it will be killed")]
            public int time { get; set; }

            [HelpOption]
            public string GetUsage()
            {
                return HelpText.AutoBuild(this, (HelpText current) => HelpText.DefaultParsingErrorsHandler(this, current));
            }
        }
    }
}