C# – How to Fix the Memory Leak in IE WebBrowser Control

cmemory-leakswebbrowser-controlwinforms

I am trying to embed a WebBrowser Control in a C# Winform Application. This sounds easy enough. However I discovered that the WebBrowser control eats up a lot of memory every time I call the Navigate method. The memory is never released. The memory usage grows and grows…

Many people on the net having the exact same problem but I haven’t found a satisfying answer yet. This is the best discussions about this issue I found so far:

Memory Leak in IE WebBrowser Control

One person suggested an upgrade to IE8 to fix the problem.

However I need a solution that works whether the user has the latest IE version installed or not. I do not have control over the users environment.

Does anybody know how to release the memory taken by the WebBrowser control? Are there workarounds? Are there alternatives to the WebBrowser control?

Update:
I just did a few more tests. At work I am running Windows XP and IE6. The memory is not growing there. The memory increases when calling the navigate method but is being released after a while. At home I am running Vista and upgraded to IE8. Here I also do not see the problem anymore. It looks like the issue is specific to IE7. So the question should be rephrased to "How to Fix the Memory Leak in IE WebBrowser Control when IE7 is installed". Can anybody confirm that this problem is specific to IE7?

Best Answer

my app was also constantly consuming memory when navigating, and not releasing anymore. i fount the solution for me here: http://social.msdn.microsoft.com/Forums/en-US/ieextensiondevelopment/thread/88c21427-e765-46e8-833d-6021ef79e0c8

for completeness ill post the notable excerpt:

-- in class definition

    [DllImport("KERNEL32.DLL", EntryPoint = "SetProcessWorkingSetSize", SetLastError = true, CallingConvention = CallingConvention.StdCall)]
    internal static extern bool SetProcessWorkingSetSize(IntPtr pProcess, int dwMinimumWorkingSetSize, int dwMaximumWorkingSetSize);

    [DllImport("KERNEL32.DLL", EntryPoint = "GetCurrentProcess", SetLastError = true, CallingConvention = CallingConvention.StdCall)]
    internal static extern IntPtr GetCurrentProcess();

-- code to call when you want to reduce the memory

        IntPtr pHandle = GetCurrentProcess();
        SetProcessWorkingSetSize(pHandle, -1, -1);

all honors to: http://social.msdn.microsoft.com/profile/mike_t2e/?type=forum&referrer=http://social.msdn.microsoft.com/Forums/en-US/ieextensiondevelopment/thread/88c21427-e765-46e8-833d-6021ef79e0c8 for posting the solution.

and http://ict-engineer.blogspot.com/2010/10/net-webbrowser-control-memory-leak.html for SEO'ing it right, so i could find it ;)

greetings

edit: if this helps you to quickly solve an issu - good. but you should overthing your application design, the pattern you use if any , refactore the thing if you build onto that much longer ....

Related Solutions

C# – How to update the GUI from another thread

The simplest way is an anonymous method passed into Label.Invoke:

// Running on the worker thread
string newText = "abc";
form.Label.Invoke((MethodInvoker)delegate {
    // Running on the UI thread
    form.Label.Text = newText;
});
// Back on the worker thread

Notice that Invoke blocks execution until it completes--this is synchronous code. The question doesn't ask about asynchronous code, but there is lots of content on Stack Overflow about writing asynchronous code when you want to learn about it.

C# – Caching and the WebBrowser control in .Net

I had the same problem (quite) a while back. Microsoft has a page that was very helpful with this:

http://support.microsoft.com/default.aspx?scid=http://support.microsoft.com:80/support/kb/articles/q326/2/01.asp&NoWebContent=1

I created a class out of Microsoft's sample, however I also had to add a couple if statements to stop processing when there are no more items; it's been a while now, but I'm pretty sure it would throw an error (see ERROR_NO_MORE_ITEMS in the code below).

I hope its helpful!

 using System;
 using System.Runtime.InteropServices;

 // copied from: http://support.microsoft.com/default.aspx?scid=http://support.microsoft.com:80/support/kb/articles/q326/2/01.asp&NoWebContent=1

 namespace PowerCode
 {
     public class IECache
     {
         // For PInvoke: Contains information about an entry in the Internet cache
         [StructLayout(LayoutKind.Explicit, Size = 80)]
         public struct INTERNET_CACHE_ENTRY_INFOA
         {
             [FieldOffset(0)]
             public uint dwStructSize;
             [FieldOffset(4)]
             public IntPtr lpszSourceUrlName;
             [FieldOffset(8)]
             public IntPtr lpszLocalFileName;
             [FieldOffset(12)]
             public uint CacheEntryType;
             [FieldOffset(16)]
             public uint dwUseCount;
             [FieldOffset(20)]
             public uint dwHitRate;
             [FieldOffset(24)]
             public uint dwSizeLow;
             [FieldOffset(28)]
             public uint dwSizeHigh;
             [FieldOffset(32)]
             public FILETIME LastModifiedTime;
             [FieldOffset(40)]
             public FILETIME ExpireTime;
             [FieldOffset(48)]
             public FILETIME LastAccessTime;
             [FieldOffset(56)]
             public FILETIME LastSyncTime;
             [FieldOffset(64)]
             public IntPtr lpHeaderInfo;
             [FieldOffset(68)]
             public uint dwHeaderInfoSize;
             [FieldOffset(72)]
             public IntPtr lpszFileExtension;
             [FieldOffset(76)]
             public uint dwReserved;
             [FieldOffset(76)]
             public uint dwExemptDelta;
         }

         // For PInvoke: Initiates the enumeration of the cache groups in the Internet cache
         [DllImport(@"wininet", SetLastError = true, CharSet = CharSet.Auto, EntryPoint = "FindFirstUrlCacheGroup", CallingConvention = CallingConvention.StdCall)]
         public static extern IntPtr FindFirstUrlCacheGroup( int dwFlags, int dwFilter, IntPtr lpSearchCondition, int dwSearchCondition, ref long lpGroupId, IntPtr lpReserved );

         // For PInvoke: Retrieves the next cache group in a cache group enumeration
         [DllImport(@"wininet", SetLastError = true, CharSet = CharSet.Auto, EntryPoint = "FindNextUrlCacheGroup", CallingConvention = CallingConvention.StdCall)]
         public static extern bool FindNextUrlCacheGroup( IntPtr hFind, ref long lpGroupId, IntPtr lpReserved );

         // For PInvoke: Releases the specified GROUPID and any associated state in the cache index file
         [DllImport(@"wininet", SetLastError = true, CharSet = CharSet.Auto, EntryPoint = "DeleteUrlCacheGroup", CallingConvention = CallingConvention.StdCall)]
         public static extern bool DeleteUrlCacheGroup( long GroupId, int dwFlags, IntPtr lpReserved );

         // For PInvoke: Begins the enumeration of the Internet cache
         [DllImport(@"wininet", SetLastError = true, CharSet = CharSet.Auto, EntryPoint = "FindFirstUrlCacheEntryA", CallingConvention = CallingConvention.StdCall)]
         public static extern IntPtr FindFirstUrlCacheEntry( [MarshalAs(UnmanagedType.LPTStr)] string lpszUrlSearchPattern, IntPtr lpFirstCacheEntryInfo, ref int lpdwFirstCacheEntryInfoBufferSize );

         // For PInvoke: Retrieves the next entry in the Internet cache
         [DllImport(@"wininet", SetLastError = true, CharSet = CharSet.Auto, EntryPoint = "FindNextUrlCacheEntryA", CallingConvention = CallingConvention.StdCall)]
         public static extern bool FindNextUrlCacheEntry( IntPtr hFind, IntPtr lpNextCacheEntryInfo, ref int lpdwNextCacheEntryInfoBufferSize );

         // For PInvoke: Removes the file that is associated with the source name from the cache, if the file exists
         [DllImport(@"wininet", SetLastError = true, CharSet = CharSet.Auto, EntryPoint = "DeleteUrlCacheEntryA", CallingConvention = CallingConvention.StdCall)]
         public static extern bool DeleteUrlCacheEntry( IntPtr lpszUrlName );

         public static void ClearCache()
         {
             // Indicates that all of the cache groups in the user's system should be enumerated
             const int CACHEGROUP_SEARCH_ALL = 0x0;
             // Indicates that all the cache entries that are associated with the cache group
             // should be deleted, unless the entry belongs to another cache group.
             const int CACHEGROUP_FLAG_FLUSHURL_ONDELETE = 0x2;
             // File not found.
             const int ERROR_FILE_NOT_FOUND = 0x2;
             // No more items have been found.
             const int ERROR_NO_MORE_ITEMS = 259;
             // Pointer to a GROUPID variable
             long groupId = 0;

             // Local variables
             int cacheEntryInfoBufferSizeInitial = 0;
             int cacheEntryInfoBufferSize = 0;
             IntPtr cacheEntryInfoBuffer = IntPtr.Zero;
             INTERNET_CACHE_ENTRY_INFOA internetCacheEntry;
             IntPtr enumHandle = IntPtr.Zero;
             bool returnValue = false;

             // Delete the groups first.
             // Groups may not always exist on the system.
             // For more information, visit the following Microsoft Web site:
             // http://msdn.microsoft.com/library/?url=/workshop/networking/wininet/overview/cache.asp            
             // By default, a URL does not belong to any group. Therefore, that cache may become
             // empty even when the CacheGroup APIs are not used because the existing URL does not belong to any group.            
             enumHandle = FindFirstUrlCacheGroup(0, CACHEGROUP_SEARCH_ALL, IntPtr.Zero, 0, ref groupId, IntPtr.Zero);

             // If there are no items in the Cache, you are finished.
             if (enumHandle != IntPtr.Zero && ERROR_NO_MORE_ITEMS == Marshal.GetLastWin32Error()) {
                 return;
             }

             // Loop through Cache Group, and then delete entries.
             while (true) {
                 if (ERROR_NO_MORE_ITEMS == Marshal.GetLastWin32Error() || ERROR_FILE_NOT_FOUND == Marshal.GetLastWin32Error()) {
                     break;
                 }

                 // Delete a particular Cache Group.
                 returnValue = DeleteUrlCacheGroup(groupId, CACHEGROUP_FLAG_FLUSHURL_ONDELETE, IntPtr.Zero);
                 if (!returnValue && ERROR_FILE_NOT_FOUND == Marshal.GetLastWin32Error()) {
                     returnValue = FindNextUrlCacheGroup(enumHandle, ref groupId, IntPtr.Zero);
                 }

                 if (!returnValue && (ERROR_NO_MORE_ITEMS == Marshal.GetLastWin32Error() || ERROR_FILE_NOT_FOUND == Marshal.GetLastWin32Error())) {
                     break;
                 }
             }

             // Start to delete URLs that do not belong to any group.
             enumHandle = FindFirstUrlCacheEntry(null, IntPtr.Zero, ref cacheEntryInfoBufferSizeInitial);
             if (enumHandle != IntPtr.Zero && ERROR_NO_MORE_ITEMS == Marshal.GetLastWin32Error()) {
                 return;
             }

             cacheEntryInfoBufferSize = cacheEntryInfoBufferSizeInitial;
             cacheEntryInfoBuffer = Marshal.AllocHGlobal(cacheEntryInfoBufferSize);
             enumHandle = FindFirstUrlCacheEntry(null, cacheEntryInfoBuffer, ref cacheEntryInfoBufferSizeInitial);

             while (true) {
                 internetCacheEntry = (INTERNET_CACHE_ENTRY_INFOA)Marshal.PtrToStructure(cacheEntryInfoBuffer, typeof(INTERNET_CACHE_ENTRY_INFOA));

                 if (ERROR_NO_MORE_ITEMS == Marshal.GetLastWin32Error()) {
                     break;
                 }

                 cacheEntryInfoBufferSizeInitial = cacheEntryInfoBufferSize;
                 returnValue = DeleteUrlCacheEntry(internetCacheEntry.lpszSourceUrlName);
                 if (!returnValue) {
                     returnValue = FindNextUrlCacheEntry(enumHandle, cacheEntryInfoBuffer, ref cacheEntryInfoBufferSizeInitial);
                 }
                 if (!returnValue && ERROR_NO_MORE_ITEMS == Marshal.GetLastWin32Error()) {
                     break;
                 }
                 if (!returnValue && cacheEntryInfoBufferSizeInitial > cacheEntryInfoBufferSize) {
                     cacheEntryInfoBufferSize = cacheEntryInfoBufferSizeInitial;
                     cacheEntryInfoBuffer = Marshal.ReAllocHGlobal(cacheEntryInfoBuffer, (IntPtr)cacheEntryInfoBufferSize);
                     returnValue = FindNextUrlCacheEntry(enumHandle, cacheEntryInfoBuffer, ref cacheEntryInfoBufferSizeInitial);
                 }
             }
             Marshal.FreeHGlobal(cacheEntryInfoBuffer);
         }
     }
 }

To use it in your code, just call:

IECache.ClearCache()

before calling the navigate methods.

Best Answer

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