C# Console.ReadLine error

Question

I have the following statement in a C# 2008 windows application that was converted to a console application:

finally
            {
                Console.ReadLine();
                Environment.Exit(1);
            }

The error message that is displayed says there is not enough io memory.

Can tell show me in code and/or point me to a reference that will show me how to solve this problem?

Vulpes · Answer

It'll depend on the size of the spreadsheets (even if they're small there's probably a default minimum allocation) but what you could do is to find out how much memory the process is using before the array of spreadsheets is created and how much memory is being used afterwards: long memUsed1 = GC.GetTotalMemory(true); // create spreadsheet array long memUsed2 = GC.GetTotalMemory(false); MessageBox.Show("The array of spreadsheets requires " + (memUsed2 - memUsed1).ToString() + " bytes");

dc · Answer

The biggest items I am placing in lists are excel spreadsheets. Let's say I have 500 to 1000 excel spreadsheets in a string array of excel spreadsheets that I am sending to the web service, can you tell me how much memory will need to be allocated?

Vulpes · Answer

It depends on how much memory you expect the process to use. Generally speaking, the .NET applications which have the highest memory footprint are those which use very large arrays, Lists or other collections (all .NET collections use arrays internally). If app2 does have such collections, I'd try and estimate how much memory is needed to accommodate them. For example, if you have an array of 10 million ints, this will use 40 million bytes because each int needs 4 bytes. Similarly, 10 million doubles (8 bytes each) requires 80 million bytes of storage. However, an array of 10 million strings will require 40 million bytes in a 32 bit app or 80 million bytes in a 64 bit app for the string references alone. The memory used by the strings themselves will be in addition. So if the average length of the strings were 10 (unicode) characters, the average string would need 28 bytes (32 bit) or 36 bytes (64 bit) of storage including overhead of 8 and 16 bytes respectively. When you multiply these figures by 10 million, it's easy to see how memory usage can build up. Although the typical machine has about 1.4 GB of usable memory, because of shortcomings in the way .NET deals with large object (85K bytes or more) you'll usually run out of memory well before then.

dc · Answer

How would I know what is too high of memory usage is for a single process? Can you tell me how to determine what is too high volume of usage?

Vulpes · Answer

1. I think that VS 2010 does have a built-in profiler in the Premium and Ultimate editions but not in the Professional edition. 2. To begin with, I'd use Task Manager to check how much memory (as a percentage of the total available) is being used as each instance of app2 is started. This is shown under the Performance tab. If this figure is very high even for a single instance, I'd then use a memory profiler to try and figure out why this is occurring. There are several available but (assuming app2 is a .NET app) I'd check out Redgate ANTS Memory Profiler which has been around a long time and there's a 14 day free trial: http://www.red-gate.com/products/dotnet-development/ants-memory-profiler/?utm_source=google&utm_medium=cpc&utm_content=unmet_need&utm_campaign=antsmemoryprofiler&gclid=CI7Q_crf4bUCFYbHtAod7SsASw

dc · Answer

Thanks for your help so far! I have the following additonnal questions: 1. To look at what is actually causing the memory problem, can I look at something like a call stack, a trace stack, and/or some other features in visual studio.net 2008 and/or visual studion.net 2010 professional editions? If so, can you tell me how to use the selected feature in visual studio? 2, Are other items I can use to determine what is causing the memory problem? Can I use something like task manager, sql profiler, an open source tool? What would you recommend and can you point me to directions on how to use the tool(s) you are recommending?

Vulpes · Answer

1. You can't change it to Environment.Exit() because it must have an int parameter. All this parameter does is determine the exit code which is returned by the operating system when the process exits. By convention, a value of 0 means the process ended normally without error and a non-zero value means that termination was abnormal for some reason or another. I usually use 1 myself for non-specific errors but you can use any value you like. 2. The parameter to the WaitForExit() method specifies the number of milliseconds to wait. So 1800 waits for 1.8 seconds. If each instance of the process is uploading and downloading multiple Office and pdf files, this isn't going to be anywhere near enough as these files tend to be large even if there's not much in them. You can only really determine how long is needed by measuring the time taken for the process to run over a reasonably large number of iterations (say 100) but I wouldn't be surprised if it ran into several minutes. 5 minutes in milliseconds is 5 * 60 * 1000 = 300000 and 10 minutes is therefore 600000. 3. Just noticed that the emboldened code in my previous post should have been: if (!eProcess.HasExited) { eProcess.Kill(); eProcess.WaitForExit(); // make sure it's stopped - shouldn't take long } as we only want to wait a second time if it's been necessary to kill the process.

dc · Answer

I have the following additional questions: 1. For the statement-Environment.Exit(1);, do you think I should change the statement to Environment.Exit();, Can you tell me if this is a good idea, why or why not? 2. For the statement, eProcess.WaitForExit(1800); Can you tell me what a reasonable amount of time would be? Basically this process needs to upload and download lots of excel, word, and pdf documents to a web service? Do you think, 5 or 10 minutes would be reasonable? In the wait statement, can you tell me what 5 minutes is and what time 10 minutes is?

Vulpes · Answer

Depending on how much memory each instance of app2 uses, I suppose it would be possible to run out of memory if you have several instances running at the same time. If you think that this could be the cause of the problem, then it would be better to wait a reasonable time and then kill the each app2 instance if it hasn't ended by then. That way you would only have (at most) a single instance of app2 running at any time: foreach (string SubPkgID in SubPkgIDs) { Process eProcess = new Process(); String Process_Arguments = null; eProcess.StartInfo.UseShellExecute = false; e_Process.StartInfo.FileName = "app2.exe"; Process_Arguments = " 3 " + SubPkgID; eProcess.StartInfo.Arguments = Process_Arguments; eProcess.Start(); eProcess.WaitForExit(1800); if (!eProcess.HasExited) eProcess.Kill(); eProcess.WaitForExit(); // make sure it's stopped - shouldn't take long eProcess.Dispose(); Process_Arguments = null; }

dc · Answer

The program that is executed is called by a C# 2010 windows application (called app1) that was converted from a console application. The following is an example of some of the calls made from app1 to the C# 2008 application that is having the memory problem called app2. string[] SubPkgIDs = rData.details.Where(c => c.Package_ID.StartsWith("SUB").Select(c => c.PackID).Distinct().ToArray(); foreach (string SubPkgID in SubPkgIDs) { { Process eProcess = new Process(); String Process_Arguments = null; eProcess.StartInfo.UseShellExecute = false; e_Process.StartInfo.FileName = "app2.exe"; Process_Arguments = " 3 " + SubPkgID; eProcess.StartInfo.Arguments = Process_Arguments; eProcess.Start(); eProcess.WaitForExit(1800); //eProcess.WaitForExit(); eProcess.Dispose(); Process_Arguments = null; } } I think the line of code that is causing the memory problem possibly is the following: eProcess.WaitForExit(1800); App1 is not waiting for a response basically from app2.exe program that is being called. It waits the 1800 *.secs and makes the next calls. There is no reason for app1 to wait or app2 to finish executing since it does not need a response from app2. However if this is causing the memory problem I can wait for the app2 program to finish executing. App1 and app2 were setup to be single threaded. In the app1 program that calls the second program called app2, I am thinking of putting the following code at the end of the program: foreach (Process proc in Process.GetProcessesByName("app2")) { proc.Kill(); } This way the app2 processes that are still in memory can be released. Thus based upon what I mentioned previously and what I just mentioned above, can you show me code and/or tell me what you would do to solve the memory problem I am having?

Vulpes · Answer

Well, it's an unusual error but it appears that there is insufficient memory to allocate a console input buffer. You could try emptying the buffer before calling Console.ReadLine() with the following line: while(Console.KeyAvailable) Console.ReadKey(true); If that doesn't work, I'd be inclined to forget calling Console.ReadLine() altogether bearing in mind you're killing the process with Environment.Exit(1) in the next line.

Hemant Srivastava · Answer

I tried your lines in my program, it's working fine. I guess...., may be you are existing from the finally block and some IO stream is still not proerly closed.

C# Console.ReadLine error

Glenn Patton