Exception when switching projects

[gene-pavlovsky]

Running FD under VS in debug mode, I'm often (not always) getting exceptions when switching projects (dev project and tests project for it), or checking out another git branch.

Exception: System.InvalidOperationException: 'Collection was modified; enumeration operation may not execute.'
Stack trace:

System.InvalidOperationException occurred
  HResult=0x80131509
  Message=Collection was modified; enumeration operation may not execute.
  Source=<Cannot evaluate the exception source>
  StackTrace:
   at System.ThrowHelper.ThrowInvalidOperationException(ExceptionResource resource)
   at System.Collections.Generic.List`1.Enumerator.MoveNextRare()
   at System.Collections.Generic.List`1.Enumerator.MoveNext()
   at HaXeContext.Context.ResolveImport(MemberModel item, MemberList imports) in C:\project\flashdevelop\External\Plugins\HaXeContext\Context.cs:line 834
   at HaXeContext.Context.ResolveImports(FileModel inFile) in C:\project\flashdevelop\External\Plugins\HaXeContext\Context.cs:line 767
   at HaXeContext.Context.ResolveType(String cname, FileModel inFile) in C:\project\flashdevelop\External\Plugins\HaXeContext\Context.cs:line 939
   at ASCompletion.Model.ClassModel.ResolveExtendedType(List`1 extensionList) in C:\project\flashdevelop\External\Plugins\ASCompletion\Model\ClassModel.cs:line 139
   at ASCompletion.Model.ClassModel.ResolveExtends() in C:\project\flashdevelop\External\Plugins\ASCompletion\Model\ClassModel.cs:line 105
   at ASCompletion.Helpers.ASTCache.UpdateClass(ClassModel cls, Dictionary`2 cache) in C:\project\flashdevelop\External\Plugins\ASCompletion\Helpers\ASTCache.cs:line 256
   at ASCompletion.Helpers.ASTCache.<UpdateOutdatedModels>b__10_0() in C:\project\flashdevelop\External\Plugins\ASCompletion\Helpers\ASTCache.cs:line 112
   at System.Runtime.Remoting.Messaging.StackBuilderSink._PrivateProcessMessage(IntPtr md, Object[] args, Object server, Object[]& outArgs)
   at System.Runtime.Remoting.Messaging.StackBuilderSink.AsyncProcessMessage(IMessage msg, IMessageSink replySink)

[SlavaRa]

I think I know the problem.

[gene-pavlovsky]

Might be a separate issue, but sometimes (when checking out other branches) another exception occurs.
Exception:
Stack trace: System.InvalidOperationException: 'Collection was modified; enumeration operation may not execute.'

System.InvalidOperationException occurred
  HResult=0x80131509
  Message=Collection was modified; enumeration operation may not execute.
  Source=<Cannot evaluate the exception source>
  StackTrace:
   at System.ThrowHelper.ThrowInvalidOperationException(ExceptionResource resource)
   at System.Collections.Generic.List`1.Enumerator.MoveNextRare()
   at System.Collections.Generic.List`1.Enumerator.MoveNext()
   at AS2Context.Context.GetModel(String package, String cname, String inPackage) in C:\project\flashdevelop\External\Plugins\AS2Context\Context.cs:line 655
   at HaXeContext.Context.ResolveType(String cname, FileModel inFile) in C:\project\flashdevelop\External\Plugins\HaXeContext\Context.cs:line 959
   at ASCompletion.Model.ClassModel.ResolveExtendedType(List`1 extensionList) in C:\project\flashdevelop\External\Plugins\ASCompletion\Model\ClassModel.cs:line 139
   at ASCompletion.Model.ClassModel.ResolveExtends() in C:\project\flashdevelop\External\Plugins\ASCompletion\Model\ClassModel.cs:line 105
   at ASCompletion.Helpers.ASTCache.UpdateClass(ClassModel cls, Dictionary`2 cache) in C:\project\flashdevelop\External\Plugins\ASCompletion\Helpers\ASTCache.cs:line 256
   at ASCompletion.Helpers.ASTCache.<UpdateCompleteCache>b__11_0() in C:\project\flashdevelop\External\Plugins\ASCompletion\Helpers\ASTCache.cs:line 165
   at System.Runtime.Remoting.Messaging.StackBuilderSink._PrivateProcessMessage(IntPtr md, Object[] args, Object server, Object[]& outArgs)
   at System.Runtime.Remoting.Messaging.StackBuilderSink.AsyncProcessMessage(IMessage msg, IMessageSink replySink)

[Neverbirth]

I definitely know the problem, but it's not a simple change if wanted to keep performance. There are many cases involved here. Everything could be locked everywhere, but I think that's an unacceptable solution.

[gene-pavlovsky]

Well you guys are very clever, you will figure out a solution :)

[Neverbirth]

I created some PR regarding this issue, but it's just a WIP I did before Christmas and couldn't continue yet.

#1936

I will try to add more information later from home regarding all the issues I found, special cases, etc. It may give some ideas, shed some light on some problems, etc.

The main issue here is that a lot of core code in FD was never thought it could run under multi-threaded scenarios, but it's not shown in that PR. The bigger the project the bigger the possibilities for this problem to appear.

[gene-pavlovsky]

@Neverbirth you can finish it, I have faith! We together!