在 for 循环中遍历 EventLogEntryCollection 时出现 IndexOutOfRangeException

Question

我目前有一个项目，每隔 x 秒（使用计时器和 10000 毫秒间隔）记录 Windows 上发生的事件，并在特定条件下过滤它们。 Timer每次做Tick，date和hour对应的10秒前（由于Interval）检查moment events，然后执行下一个方法：

// Method that returns wanted events from an EventLogEntryCollection
private List<EventLogEntry> lastEvents(EventLogEntryCollection eventsList, DateTime minimumMoment)
{
    // Wanted events list
    // 4624: Login
    // 4634: Logout
    long[] events = new long[] { 4624, 4634 };

    // Table to return with valid events
    List<EventLogEntry> filteredEventsList = new List<EventLogEntry>();

    // Checking if there are events to filter
    if (eventsList.Count > 0)
    {
        // There are events to filter
        // Going across all events to filter
        for (int i = 0; i < eventsList.Count; i++)
        {
            // Getting the current event
            EventLogEntry event = eventsList[i];   // Line with exception

            // Checking if the current event happened in the last 10 seconds (due to the Interval)
            if (event.TimeGenerated >= minimumMoment)
            {
                // The event is valid time wise
                // Checking if the event's ID is contained in the required ID's list
                if (events.Contains(event.InstanceId))
                {
                    // The event has a valid ID
                    // Adding the event to the list
                    filteredEventsList.Add(event);
                }
            }
        }
    }

    // Returning obtained list
    return filteredEventsList;
}

该事件获取所有事件的列表（通过使用 EventLog.Entries 获取）以及事件必须添加到过滤事件列表中的日期和时间（因此必须生成一个事件 10秒前为 'accepted'）。但是，在 eventsList 迭代期间，在第一次测试中生成了一个 IndexOutOfRangeException，在 28000 左右，在第二次测试中生成了 43，并且在这两个测试中生成了 Count 属性在 31000 左右。 ¿有人能告诉我为什么会这样吗？

这是异常数据的屏幕截图（对不起，它是西班牙语）： IndexOutOfRange exception data

Answer 1

根据the docs：

EventLogEntry objects are indexed by the event log system according to the chronological order in which they arrived in the event log. Use the Item[Int32] property to select a specific event log entry whose index in the collection is known.

Iterating through the EventLogEntryCollection instance steps through each EventLogEntry object sequentially. The collection is dynamic and the number of entries may not be immutable when you enter the loop. Therefore, you should use a for each...next loop instead of a for loop to step through entries that are associated with the EventLogEntryCollection instance to examine the entire set of entries.

Because new entries are appended to the existing list, stepping through the collection enables you to access the entries that were created after you originally created the EventLogEntryCollection.

此外，Count 的文档，状态：

An EventLogEntryCollection represents a dynamic list of all the entries in a log. Therefore, the Count property can change during the lifetime of the EventLogEntryCollection instance that you create. It is usually best to work with the Count property directly instead of assigning its value to a variable.

因此，简而言之，Count 正在发生变化（可能会减少）- 导致您查找不再存在的索引。使用 foreach 而不是 for 将为您解决这个问题。

在 for 循环中遍历 EventLogEntryCollection 时出现 IndexOutOfRangeException

IndexOutOfRangeException when iterating through a EventLogEntryCollection in a for loop

c#

event-log

indexoutofrangeexception