在Server 2008 SP2上对Win32_PageFileUsage类运行WMI查询时出现内存泄漏

Question

Running WMI query against Win32_PageFileUsage class causes a memory leak. In my situation it is being done to 200 servers every 5 minutes. After about 3 hours the memory leak is nearly 10 GB. I think it is somehow relaited to that fact, that the pagefile does not exist. The value is "0". Here is my code:

...
ObjectQuery pageFileUsageQuery = 
        new ObjectQuery("SELECT AllocatedBaseSize, CurrentUsage FROM Win32_PageFileUsage");
m_PageFileUsageSearcher = new ManagementObjectSearcher(managementScope, pageFileUsageQuery);
...
var pageFileUsageCollection = m_PageFileUsageSearcher.Get();
double currentUsage = 0;
double maxSize = 0;

foreach (ManagementBaseObject managementBaseObject in pageFileUsageCollection)
{
        string result = managementBaseObject["CurrentUsage"].ToString();
        currentUsage += double.Parse(result);
}

The system is Windows Server 2008 SP2. Maybe somebody has any ideas?

Answer 1

ManagementObjectSearcher implements IDisposable (as does ManagementObjectCollection and ManagementBaseObject ). You should dispose of these... perhaps with well placed using statements.

ObjectQuery pageFileUsageQuery = 
        new ObjectQuery("SELECT AllocatedBaseSize, CurrentUsage FROM Win32_PageFileUsage");
using(m_PageFileUsageSearcher = new ManagementObjectSearcher(managementScope, pageFileUsageQuery))
{
    ...
    using(var pageFileUsageCollection = m_PageFileUsageSearcher.Get())
    {
        double currentUsage = 0;
        double maxSize = 0;

        foreach (ManagementBaseObject managementBaseObject in pageFileUsageCollection)
        {
            try
            {
                string result = managementBaseObject["CurrentUsage"].ToString();
                currentUsage += double.Parse(result);
            }
            finally
            {
                managementBaseObject.Dispose();
            }
        }
    }
}

Answer 2

As per comment above by michael-graczyk, there is a bug in the Dispose of …

Calling GC.WaitForPendingFinalizers() once is enough to fix it

though we do not consider it a solution really, just a workaround.