Question

我创建了一个XRMTool（WPF）来将数据从Dynamics CRM Online提取到XML文件。输出文件可能有一百万行，但我收到以下错误。

无法分配2147483647字节的托管内存缓冲区。可用内存量可能很低。

我可以添加一些过滤器并减少行数，但根据应用程序的要求，我必须一次性提取至少一个月的数据，这将是大约一百万行。

如何在WPF应用程序中增加内存缓冲区？

以下是我的代码

            string fetchaudit = @"<fetch version='1.0' mapping='logical'  output-format='xml-platform'>
        <entity name='audit'>
        <attribute name='action' />
        <attribute name='auditid' />
        <attribute name='callinguserid' />
        <attribute name='objecttypecode' />
        <attribute name='createdon' />
        <attribute name='objectid' />
        <attribute name='objectid' />
        <attribute name='operation' />
        <attribute name='regardingobjectid' />
        <attribute name='transactionid' />
        <attribute name='userid' />
        <filter type='and'>
        <condition attribute='createdon' operator='on-or-after' value='" + Fromdate + @"' />
        <condition attribute='createdon' operator='on-or-before' value='" + Todate + @"' />
        </filter>
        </entity>
       </fetch>";
     while (true)
       {
            string xml = CreateXml(fetchaudit, pagingCookie, pageNumber, fetchCount);
            RetrieveMultipleRequest fetchRequest1 = new RetrieveMultipleRequest
            {
                Query = new FetchExpression(xml) // Error occurs here when page number reaches 100
            };
            EntityCollection returnCollection = ((RetrieveMultipleResponse)_ctrl.CrmConnectionMgr.CrmSvc.Execute(fetchRequest1)).EntityCollection;

           // var collection = _ctrl.CrmConnectionMgr.CrmSvc.GetEntityDataByFetchSearchEC(xml);
            if (returnCollection != null)
           {
                if (returnCollection.Entities.Count >= 0)
                    Entities.AddRange(returnCollection.Entities);

            }
            if (returnCollection.MoreRecords)
            {
                pageNumber++;
                pagingCookie = returnCollection.PagingCookie;
            }
            else
            {
                break;
            }
        } // end while

我在SDK中使用以下方法进行分页SampleCode \ CS \ GeneralProgramming \ Queries \ FetchPagingWithCookie.cs（https://msdn.microsoft.com/en-us/library/gg309717.aspx）

Answer 1

很可能在第一个请求中没有发生异常，如果是，则减少返回行的数量。

您当前的问题是您将所有内容存储在内存中，直到检索结束

Entities.AddRange(returnCollection.Entities);

Entities的集合正在快速增长，但由于在实际SDK检索时发生内存分配，因此添加失败。

要将查询结果序列化为具有DataContractSerializer的单个集合，您可以使用下一个IEnumerable实现来按包读取数据（and more clarifications for the code）：

public class XrmEnumerator<T> : IEnumerator<T> where T : Entity
{
    private readonly Queue<T> _collected = new Queue<T>();
    private IOrganizationService _service;
    private QueryExpression _query;
    private string _lastCookie;
    private bool _moreRecords;

    public T Current { get; private set; }
    object IEnumerator.Current => Current;

    public XrmEnumerator(IOrganizationService service, QueryExpression query)
    {
        _service = service;
        _query = query;
        if (query.PageInfo == null)
            query.PageInfo = new PagingInfo
            {
                Count = 5000,
                PageNumber = 1
            };
        FillThePack();
    }

    private void FillThePack()
    {
        var result = _service.RetrieveMultiple(_query);
        _lastCookie = result.PagingCookie;
        result.Entities.ToList().ForEach(e=>_collected.Enqueue(e.ToEntity<T>()));
        _moreRecords = result.MoreRecords;
    }

    public void Dispose()
    {
        _service = null;
        _query = null;
    }

    public bool MoveNext()
    {
        if(_collected.Count == 0)
        {
            if (!_moreRecords)
            {
                return false;
            }
            _query.PageInfo.PagingCookie = _lastCookie;
            _query.PageInfo.PageNumber++;
            FillThePack();
        }
        Current = _collected.Dequeue();
        return true;
    }

    public void Reset()
    {
        _query.PageInfo.PagingCookie = string.Empty;
        _query.PageInfo.PageNumber = 1;
    }
}

public class XrmEnumerable<T> : IEnumerable<T> where T : Entity
{
    private readonly XrmEnumerator<T> _enumerator;

    public XrmEnumerable(IOrganizationService service, QueryExpression query)
    {
        _enumerator = new XrmEnumerator<T>(service, query);
    }

    public IEnumerator<T> GetEnumerator() => _enumerator;

    IEnumerator IEnumerable.GetEnumerator()
    {
        return _enumerator;
    }

    public virtual void Add(T entity)
    {
        // do your code on item deserialization
    }
}

它使用的是QueryExpression而不是FetchXml，但你可以使用easily convert it

使用样本：

var enumerable = new XrmEnumerable<Contact>(service, query);
var serializer = new DataContractSerializer(typeof(XrmEnumerable<Contact>));
using (var file = File.OpenWrite("contacts.xml"))
    serializer.WriteObject(file, enumerable);

另外，您可以创建XrmEnumerable的子类，并在Add函数中执行逻辑

Dynamics CRM Xrm工具错误“无法分配2147483647字节的托管内存缓冲区。”

1 个答案: