Tutorial :C# Compact Framework - OutOfMemoryException with XmlSerializer.Serialize


I'm trying to serialize a large collection of objects (20,000) objects within the collection. I'm doing this using the following code:

XmlSerializer xs = new XmlSerializer(deserialized.GetType());  StringWriter sw;  using (sw = new StringWriter())  {     xs.Serialize(sw, deserialized);   // OutOfMemoryException here  }    string packet = sw.ToString();  return packet;  

Is there a better way of doing this, or am I doing something blatantly wrong?


It looks like it should work, but CF does have unpredictable limitations.

Is xml a requirement? I can't remember trying it with 20k records, but another option might be to try using a different serializer - for example, protobuf-net works on CF2. I can't guarantee it'll work, but it might be worth a shot.

(in particular, I'm currently refactoring the code to try to work around some additional "generics" limitations within CF - but unless you have a very complex object model this shouldn't affect you).

Example showing usage; note that this example also works OK for XmlSerializer, but protobuf-net uses only 20% of the space (or 10% of the space if you consider that characters are two bytes each in memory):

using System;  using System.Collections.Generic;  using System.IO;  using System.Xml.Serialization;  using ProtoBuf;    [Serializable, ProtoContract]  public class Department  {      [ProtoMember(1)]      public string Name { get; set; }      [ProtoMember(2)]      public List<Person> People { get; set; }  }    [Serializable, ProtoContract]  public class Person  {      [ProtoMember(1)]      public int Id { get; set; }      [ProtoMember(2)]      public string Name { get; set; }      [ProtoMember(3)]      public DateTime DateOfBirth { get; set; }  }      static class Program  {      [MTAThread]      static void Main()      {          Department dept = new Department { Name = "foo"};          dept.People = new List<Person>();          Random rand = new Random(123456);          for (int i = 0; i < 20000; i++)          {              Person person = new Person();              person.Id = rand.Next(50000);              person.DateOfBirth = DateTime.Today.AddDays(-rand.Next(2000));              person.Name = "fixed name";              dept.People.Add(person);          }            byte[] raw;          using (MemoryStream ms = new MemoryStream())          {              Serializer.Serialize(ms, dept);              raw = ms.ToArray(); // 473,399 bytes          }            XmlSerializer ser = new XmlSerializer(typeof(Department));          StringWriter sw = new StringWriter();          ser.Serialize(sw, dept);          string s = sw.ToString(); // 2,115,693 characters      }  }  

Let me know if you want more help - I can talk about this subject all day ;-p Note that it can work just from the standard xml attributes ([XmlElement(Order=1)]) - I've used the more specific [ProtoMember(1)] etc for clarity. This also allows fine-grained control of serialization (zigzag vs twoscompliment, grouped vs length-prefixed, etc).


Do you have any metrics on your application's memory consumption? I'm assuming you're running on WM, which means that each process' address space is limited to 32MB. With a large XML, it's possible that you've actually run out of memory.


Maybe you could consider persisting the individual objects (rather than persisting the collection as one big block). If so, you might want to use the NFileStorage project I created on codeplex; nfilestorage.codeplex.com (this one is not specifically made for the CF, so cannot tell if its compatible with that one)...

Good luck, Gert-Jan

Note:If u also have question or solution just comment us below or mail us on toontricks1994@gmail.com
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