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.NET Forum / ASP.NET / General / July 2005Do I need to use GC.Collect? If yes, where?
Hello, here is what I am doing. 1) user accesses web page and clicks button to build report 2) web page accesses web service whose data type is DataSet (public DataSet methodname()...) 3) web service connects to SqlServer, runs BIG report 4) data is returned to web service, web service returns DataSet to web front-end 5) web front-end prompts user to save Excel file which contains the DataSet data While #3 is running, the aspnet_ws.exe process on the web server grows big, like 200-500 MB. The problem is the server doesn't seem to release that memory after the report is done. A few more report runs and the server starts giving memory errors. I have seen people saying use GC.Collect() but where would I put that? Antonio, No, you shouldn't be calling GC.Collect, ^especially^ in an ASP.NET environment. ASP.NET gets into a nice little groove (in terms of GC's, and when the pattern of use is consistent) which you don't want to mess with by running your own GC's. The errors that you are probably getting are due to the % of memory ASP.NET is allowed to use before the process is recycled. You would have to up this value in the web.config file for your application, to let your ASP.NET process take up more memory. If your report is returning data that is between 200-500 MB, then you really need to reconsider the design of the report. Also, Task Manager is not really suitable for monitoring the memory consumption of an application. You should be using the performance counters to determine what is being consumed/released, etc, etc. In the end, ^don't^ call GC.Collect, as in this case, it isn't going to do anything for you. Just make sure you dispose of all types that implement IDisposable, and if your report is really that big, then raise the value of the allowed memory consumption in the web.config file. Hope this helps.  Signature- Nicholas Paldino [.NET/C# MVP] - mvp@spam.guard.caspershouse.com > Hello, here is what I am doing. > [quoted text clipped - 15 lines] > > I have seen people saying use GC.Collect() but where would I put that? ok so don't call GC.Collect(). I have added .Dispose to the datagrids and datasets. The actual excel file downloaded is usually between 5 and 25 MB. I am not really sure why the process grows by 200 or more MB. What performance counters would you suggest I watch in perfmon? thank you Nicholas The question is not how big is the excel file, the question is how big is the dataset. And what datagrids are you talking about? This is a webservice, what are the datagrids used for? Willy. > ok so don't call GC.Collect(). I have added .Dispose to the datagrids > and datasets. The actual excel file downloaded is usually between 5 > and 25 MB. I am not really sure why the process grows by 200 or more > MB. What performance counters would you suggest I watch in perfmon? > > thank you Nicholas The datagrid is to get the excel output. See below. I found this in the asp.net ng. I call the web service which returns the dataset, then I pass the dataset into this static method (I made it a static method so all of my web pages can call it. public static void ExportExcel(System.Data.DataSet ds, int TableIndex, string FileNameNoExtension, System.Web.HttpResponse response) { response.Clear(); response.Charset = ""; response.ContentType = "application/vnd.ms-excel"; response.AddHeader("content-disposition", "attachment;filename=" + FileNameNoExtension + ".xls"); System.IO.StringWriter stringWrite = new System.IO.StringWriter(); System.Web.UI.HtmlTextWriter htmlWrite = new System.Web.UI.HtmlTextWriter(stringWrite); System.Web.UI.WebControls.DataGrid dg = new System.Web.UI.WebControls.DataGrid(); dg.DataSource = ds.Tables[TableIndex]; dg.DataBind(); dg.RenderControl(htmlWrite); response.Write(stringWrite.ToString()); response.End(); ds.Dispose(); } > The datagrid is to get the excel output. See below. I found this in > the asp.net ng. I call the web service which returns the dataset, then [quoted text clipped - 20 lines] > ds.Dispose(); > } Ok, if I understand you correctly, you have following logical tiers: 1. browser client 2. a web application (asp.net) 3. a web service 4. a SQL DB How about the physical tiers, do 2 and 3 run on the same server (not really a server, if I'm not mistaken you run this on XP)? Who's producing the Excel output? And what's the relation between this and the DS generated by the report? How large is the dataset passed from the WS to the WA, this is important as if both run in the same process (aspnet_wp.exe) the working set will contain two instances of the same DS at some point in time. Willy. Yes! The server are Windows Server 2000 SP4. 2 and 3 DO run on the same server! #2 is producing the excel file. #3 only connects to the database and returns to #2 the dataset. then the dataset is handed to the static method that productces the excel file. I do not know how big the dataset is but I will try to look. > Yes! > [quoted text clipped - 4 lines] > > I do not know how big the dataset is but I will try to look. Does 2 produce the Excel file through Office automation (COM)? If the answer is yes, then all I can say is change you design and don't run Office automation on the server from web applications. Office is not designed to be used in such scenarios, "it doesn't scale" is an often heard issue but it's not the worse. Check following KB article as to why it is like this: http://support.microsoft.com/default.aspx?scid=kb;en-us;257757 Willy. Yes thank you that is a great answer. This is not using COM or any office interop though. Please see the code in my earlier post. Maybe I can try to pass to the static method the dataset by ref as to not copy it in memory. Does that make a good suggestion? Antonio, It depends on what you want to see. If you run perfmon (from the run dialog box), you will see a gazillion (ok, almost) entries for performance counters. You can see things such as number of collections, memory allocated, etc, etc. They are pretty self-describing, and can give you a plethora of information. Also, when working with the Excel sheet, you should make sure that you call the static ReleaseComObject on the Marshal class to correctly release the COM objects produced by it (it can leave references lying around). Signature- Nicholas Paldino [.NET/C# MVP] - mvp@spam.guard.caspershouse.com > ok so don't call GC.Collect(). I have added .Dispose to the datagrids > and datasets. The actual excel file downloaded is usually between 5 > and 25 MB. I am not really sure why the process grows by 200 or more > MB. What performance counters would you suggest I watch in perfmon? > > thank you Nicholas > Hello, here is what I am doing. > [quoted text clipped - 15 lines] > > I have seen people saying use GC.Collect() but where would I put that? You would probably add a GC.Collect after you call Dispose on the object. However, I wonder if that is the problem? Is your 200-500 MB data a group of unmanaged Excel objects? If so, are you sure you're releasing ALL of the objects? Carl Are you releasing your Excel references with Marshal.ReleaseCOMObject, or just setting them to null? http://support.microsoft.com/default.aspx?scid=kb;EN-US;Q317109 Please note that this is one of the cases where MS actually does reference manually calling GC.Collect ... although it's sort of a hack to deal with reference counting problems in the RCW. > Hello, here is what I am doing. > [quoted text clipped - 15 lines] > > I have seen people saying use GC.Collect() but where would I put that? 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