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POWCF timeout against Azure WebRole when serializing certain types of collections
 

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  1. POWCF timeout against Azure WebRole when serializing certain types of collections
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    <p>I have a stateless backend service hosted on an <strong>Azure Web Role</strong> which queries an <strong>Entity Framework</strong> container, among other things. Clients communicate with it using <strong>WCF</strong> and <code>wsHttpBinding</code>. <strong>The clients receive a timeout from backend when calling certain methods</strong>, and even though I worked around this in some cases, I can't seem to pinpoint the underlying cause.</p> <p>Here's what I know so far:</p> <ul> <li>The failing methods seem to be the ones that return certain types of collections. This includes <code>IEnumerable&lt;T&gt;</code> with results obtained from LINQ queries, and <code>MembershipUserCollection</code>.</li> <li>In some cases the workaround was to add <code>.ToList()</code> to the collection being returned.</li> <li>Those methods fail <strong>only</strong> when the backend is hosted in Azure. </li> <li>The Azure load balancer doesn't seem to be the cause but the symptom: every time a method times out, the log reveals that it had actually exited long before the 1 minute limit.</li> </ul> <p>And here's one of the methods that fail:</p> <p><strong>WCF interface</strong>:</p> <pre><code> [OperationContract(Action = "http://tempuri.org/IBackendService/GetAllUsers", ReplyAction = "http://tempuri.org/IBackendService/GetAllUsersResponse")] MembershipUserCollection GetAllUsers(int pageIndex, int pageSize, out int totalRecords); </code></pre> <p><strong>WCF Implementation</strong> (simplified):</p> <pre><code> protected UserRepository Users; public override MembershipUserCollection GetAllUsers(int pageIndex, int pageSize, out int totalRecords) { // Get all users in the page range specified. var userEntities = Users.GetAll(); var users = new MembershipUserCollection(); userEntities = userEntities.GetPagedRange(pageIndex, pageSize).ToList(); userEntities.ForEach(ue =&gt; users.Add(Mappings.Map&lt;UserEntity, User&gt;(ue))); totalRecords = userEntities.Count(); return users; } </code></pre> <p><strong>Mappings</strong> is a class that defines mapping rules between data and business objects using AutoMapper. <code>User</code> inherits from <code>MembershipUser</code>. Here's what's relevant from it: (WIP. Please excuse the mess.)</p> <pre><code> Mapper.CreateMap&lt;UserEntity, User&gt;() .ConstructUsing(ue =&gt; new User ( ue.UserId, ue.ProviderName, ue.UserName, ue.Email, ue.PasswordQuestion, ue.IsApproved, ue.IsLockedOut, ue.CreationDate, ue.LastLoginDate.HasValue ? ue.LastLoginDate.Value : DateTime.MinValue, ue.LastActivityDate.HasValue ? ue.LastActivityDate.Value : DateTime.MinValue, ue.LastPasswordChangedDate.HasValue ? ue.LastPasswordChangedDate.Value : DateTime.MinValue, ue.LastLockoutDate.HasValue ? ue.LastLockoutDate.Value : DateTime.MinValue, ue.Comment, ue.Customers.Select(Map&lt;CustomerEntity, Customer&gt;).ToList(), ue.Roles.Select(Map&lt;RoleEntity, Role&gt;).ToList(), ue.Roles.SelectMany(r =&gt; r.Activities).Select(Map&lt;ActivityEntity, Activity&gt;).ToList() )) .IgnoreAllNonExisting(); Mapper.CreateMap&lt;User, UserEntity&gt;() .ForMember(ue =&gt; ue.Comment, opt =&gt; opt.MapFrom(u =&gt; u.Comment)) .ForMember(ue =&gt; ue.CreationDate, opt =&gt; opt.MapFrom(u =&gt; u.CreationDate)) .ForMember(ue =&gt; ue.Email, opt =&gt; opt.MapFrom(u =&gt; u.Email)) .ForMember(ue =&gt; ue.IsApproved, opt =&gt; opt.MapFrom(u =&gt; u.IsApproved)) .ForMember(ue =&gt; ue.IsLockedOut, opt =&gt; opt.MapFrom(u =&gt; u.IsLockedOut)) .ForMember(ue =&gt; ue.LastActivityDate, opt =&gt; opt.MapFrom(u =&gt; u.LastActivityDate.Equals(DateTime.MinValue) ? (DateTime?)null : u.LastActivityDate)) .ForMember(ue =&gt; ue.LastLockoutDate, opt =&gt; opt.MapFrom(u =&gt; u.LastLockoutDate.Equals(DateTime.MinValue) ? (DateTime?)null : u.LastLockoutDate)) .ForMember(ue =&gt; ue.LastLoginDate, opt =&gt; opt.MapFrom(u =&gt; u.LastLoginDate.Equals(DateTime.MinValue) ? (DateTime?)null : u.LastLoginDate)) .ForMember(ue =&gt; ue.LastPasswordChangedDate, opt =&gt; opt.MapFrom(u =&gt; u.LastPasswordChangedDate.Equals(DateTime.MinValue) ? (DateTime?)null : u.LastPasswordChangedDate)) .ForMember(ue =&gt; ue.PasswordQuestion, opt =&gt; opt.MapFrom(u =&gt; u.PasswordQuestion)) .ForMember(ue =&gt; ue.ProviderName, opt =&gt; opt.MapFrom(u =&gt; u.ProviderName)) .ForMember(ue =&gt; ue.UserId, opt =&gt; opt.MapFrom(u =&gt; (int)u.ProviderUserKey)) .ForMember(ue =&gt; ue.UserName, opt =&gt; opt.MapFrom(u =&gt; u.UserName)) .ForMember(ue =&gt; ue.Password, opt =&gt; opt.Ignore()) .ForMember(ue =&gt; ue.PasswordAnswer, opt =&gt; opt.Ignore()) .ForMember(ue =&gt; ue.ApplicationName, opt =&gt; opt.Ignore()) .ForMember(ue =&gt; ue.Roles, opt =&gt; opt.Ignore()) .ForMember(ue =&gt; ue.Customers, opt =&gt; opt.Ignore()) .IgnoreAllNonExisting(); </code></pre> <p><strong>IgnoreAllNonExisting</strong> is an extension method:</p> <pre><code> public static IMappingExpression&lt;TSource, TDestination&gt; IgnoreAllNonExisting&lt;TSource, TDestination&gt;(this IMappingExpression&lt;TSource, TDestination&gt; expression) { var sourceType = typeof(TSource); var destinationType = typeof(TDestination); var existingMaps = Mapper.GetAllTypeMaps().First(x =&gt; x.SourceType == sourceType &amp;&amp; x.DestinationType == destinationType); foreach (var property in existingMaps.GetUnmappedPropertyNames()) { expression.ForMember(property, opt =&gt; opt.Ignore()); } return expression; } </code></pre> <p>My best guess is that this is a serialization problem in the WCF layer, but I don't know what might be triggering it. Other than that, I'm completely clueless. </p> <p>What else should I check? Do you need any more info?</p> <p><strong>EDIT: Added moar snippets for clarification.</strong></p>
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    1. USAxel Magagnini
    1. USAxel Magagnini
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    1. COWhere does Mappings.Map come from? Sometimes there can be EF serialization issues with Lazy Loading of navigable properties causing recursive serialization
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      1. POWCF timeout against Azure WebRole when serializing certain types of collections
      1. USNeil Thompson
    2. COThanks for your reply. That's a helper class that creates AutoMapper rules to map data objects to business objects and vice versa. I'll add a snippet for clarification, forgot about that one.
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      1. POWCF timeout against Azure WebRole when serializing certain types of collections
      1. USAxel Magagnini
    3. COAha. I use ValueInjector. They are both gr8. Are the collections that fail collections like User where a User has a Roles Collection and each Role might have a Users Collection. Automapper might be clever enough to not serialize forever but you might be timing out returning every user in your system?
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      1. POWCF timeout against Azure WebRole when serializing certain types of collections
      1. USNeil Thompson
 

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