Crystal Reports 13 Maximum Report Processing Limit Reached Workaround

In the Visual Studio 2012 version of Crystal Reports 13 there is a threshold that throttles concurrent reports, this also includes subreports, to 75 reports across a machine. This means if there are 5 web applications on a given server all opened reports across all 5 web applications counts toward the 75 report limit.

The error manifests itself in different ways and may result in the following errors “Not enough memory for operation.” or “The maximum report processing jobs limit configured by your system administrator has been reached”.

The problem is the reports are not disposed and they continue accumulate until the 75 limit is hit. To fix this issue, the reports have to be disposed of at the earliest possible time. This sounds simple, but is not as straightforward as it seems. Depending how the reports are generated there are two scenarios: First is generating PDF’s or Excel spreadsheets and the second is using the Crystal Report Viewer. Each scenario has a different lifetime, which we need to take into account when crafting our solution.

Solution

There are two reports lifetimes we have to manage: generated reports: PDF, Excel Spreadsheet and the Crystal Report viewer.

PDF’s and Excel Spreadsheets are generated during the request. They can be disposed on the Page Unload event. The Crystal Report viewer is a bit different. It needs to span requests and is stored in session. This makes disposing the viewer reports a bit challenging, but not impossible.

Disposing the Viewer on the Page Unload event won’t work. The Viewer has paging functionality which requests each new page from the server. To get around this issue we implemented a report reference counter. Each time a report is created, it is stored in a concurrent dictionary. When a report is disposed the report is removed from the dictionary. Upon opening a type of a report we check that the user does not already have this report open, if they do, we simply dispose the existing report and open a new one in it’s place. Other opportunities to dispose the report is on Session End (the user signs out), on Application End and when navigating away from report page.

Our internal QA team tested a non fixed version of Crystal Reports. Crystal Reports fell over at around 100 concurrent connections. After applying the fix our QA team ran a load against the servers at 750 concurrent connections without any issues.

On a side note, we have encountered latency when disposing reports with multiple sub reports.

public static class ReportFactory
{
static readonly ConcurrentDictionary<string, ConcurrentDictionary<string, UserReport>> _sessions = new ConcurrentDictionary<string, ConcurrentDictionary<string, UserReport>>();

/// <summary>
/// Creates the report dispose on unload.
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="page">The page.</param>
/// <returns>``0.</returns>
public static T CreateReportDisposeOnUnload<T>(this Page page) where T : IDisposable, new()
{
    var report = new T();
    DisposeOnUnload(page, report);
    return report;
}

/// <summary>
/// Disposes on page unload.
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="page">The page.</param>
/// <param name="instance">The instance.</param>
private static void DisposeOnUnload<T>(this Page page, T instance) where T : IDisposable
{
    page.Unload += (s, o) =>
    {
        if (instance != null)
        {
            CloseAndDispose(instance);
        }
    };
}

/// <summary>
/// Unloads the report when user navigates away from report.
/// </summary>
/// <param name="page">The page.</param>
public static void UnloadReportWhenUserNavigatesAwayFromPage(this Page page)
{
    var sessionId = page.Session.SessionID;
    var pageName = Path.GetFileName(page.Request.Url.AbsolutePath);

    var contains = _sessions.ContainsKey(sessionId);

    if (contains)
    {
        var reports = _sessions[sessionId];
        var report = reports.Where(r => r.Value.PageName != pageName).ToList();

        foreach (var userReport in report)
        {
            UserReport instance;

            bool removed = reports.TryRemove(userReport.Key, out instance);

            if (removed)
            {
                CloseAndDispose(instance.Report);
            }
        }
    }
}

/// <summary>
/// Gets the report.
/// </summary>
/// <typeparam name="T"></typeparam>
/// <returns>ReportClass.</returns>
public static T CreateReportForCrystalReportViewer<T>(this Page page) where T : IDisposable, new()
{
    var report = CreateReport<T>(page);
    return report;
}

/// <summary>
/// Creates the report.
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="page">The page.</param>
/// <returns>``0.</returns>
private static T CreateReport<T>(Page page) where T : IDisposable, new()
{
    MoreThan70ReportsFoundRemoveOldestReport();

    var sessionId = page.Session.SessionID;

    bool containsKey = _sessions.ContainsKey(sessionId);
    var reportKey = typeof(T).FullName;
    var newReport = GetUserReport<T>(page);

    if (containsKey)
    {
        //Get user by session id
        var reports = _sessions[sessionId];

        //check for the report, remove it and dispose it if it exists in the collection
        RemoveReportWhenMatchingTypeFound<T>(reports);

        //add the report to the collection

        reports.TryAdd(reportKey, newReport);

        //add the reports to the user key in the concurrent dictionary
        _sessions[sessionId] = reports;
    }
    else //key does not exist in the collection
    {
        var newDictionary = new ConcurrentDictionary<string, UserReport>();
        newDictionary.TryAdd(reportKey, newReport);

        _sessions[sessionId] = newDictionary;

    }

    return (T)newReport.Report;
}

/// <summary>
/// Ifs the more than 70 reports remove the oldest report.
/// </summary>
private static void MoreThan70ReportsFoundRemoveOldestReport()
{
    var reports = _sessions.SelectMany(r => r.Value).ToList();

    if (reports.Count() > 70)
    {
        //order the reports with the oldest on top.
        var sorted = reports.OrderByDescending(r => r.Value.TimeAdded);

        //remove the oldest
        var first = sorted.FirstOrDefault();
        var key = first.Key;
        var sessionKey = first.Value.SessionId;

        if (first.Value != null)
        {
            //close and depose of the first report
            CloseAndDispose(first.Value.Report);

            var dictionary = _sessions[sessionKey];
            var containsKey = dictionary.ContainsKey(key);

            if (containsKey)
            {
                //remove the disposed report from the collection
                UserReport report;
                dictionary.TryRemove(key, out report);
            }
        }

    }
}

/// <summary>
/// Removes the report if there is a report with a match type.
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="reports">The reports.</param>
private static void RemoveReportWhenMatchingTypeFound<T>(ConcurrentDictionary<string, UserReport> reports) where T : IDisposable, new()
{
    var key = typeof(T).FullName;
    var containsKey = reports.ContainsKey(key);

    if (containsKey)
    {
        UserReport instance;

        bool removed = reports.TryRemove(key, out instance);

        if (removed)
        {
            CloseAndDispose(instance.Report);
        }

    }
}

/// <summary>
/// Removes the reports for session.
/// </summary>
/// <param name="sessionId">The session identifier.</param>
public static void RemoveReportsForSession(string sessionId)
{
    var containsKey = _sessions.ContainsKey(sessionId);

    if (containsKey)
    {
        ConcurrentDictionary<string, UserReport> session;

        var removed = _sessions.TryRemove(sessionId, out session);

        if (removed)
        {
            foreach (var report in session.Where(r => r.Value.Report != null))
            {
                CloseAndDispose(report.Value.Report);
            }
        }
    }
}

/// <summary>
/// Closes the and dispose.
/// </summary>
/// <param name="report">The report.</param>
private static void CloseAndDispose(IDisposable report)
{
    report.Dispose();
}

/// <summary>
/// Gets the user report.
/// </summary>
/// <typeparam name="T"></typeparam>
/// <returns>UserReport.</returns>
private static UserReport GetUserReport<T>(Page page) where T : IDisposable, new()
{
    string onlyPageName = Path.GetFileName(page.Request.Url.AbsolutePath);

    var report = new T();
    var userReport = new UserReport { PageName = onlyPageName, TimeAdded = DateTime.UtcNow, Report = report, SessionId = page.Session.SessionID };

    return userReport;
}

/// <summary>
/// Removes all reports.
/// </summary>
public static void RemoveAllReports()
{
    foreach (var session in _sessions)
    {
        foreach (var report in session.Value)
        {
            if (report.Value.Report != null)
            {
                CloseAndDispose(report.Value.Report);
            }
        }

        //remove all the disposed reports
        session.Value.Clear();
    }

    //empty the collection
    _sessions.Clear();
}

private class UserReport
{
    /// <summary>
    /// Gets or sets the time added.
    /// </summary>
    /// <value>The time added.</value>
    public DateTime TimeAdded { get; set; }

    /// <summary>
    /// Gets or sets the report.
    /// </summary>
    /// <value>The report.</value>
    public IDisposable Report { get; set; }

    /// <summary>
    /// Gets or sets the session identifier.
    /// </summary>
    /// <value>The session identifier.</value>
    public string SessionId { get; set; }

    /// <summary>
    /// Gets or sets the name of the page.
    /// </summary>
    /// <value>The name of the page.</value>
    public string PageName { get; set; }
}
}

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