BUG: You receive a "BASE: GlobalFree called with a locked object" error message when you try to free a global memory that is attached to a CSharedFile object (148455)
The information in this article applies to:
- The Microsoft Foundation Classes (MFC), when used with:
- Microsoft Visual C++, 32-bit Editions 2.0
- Microsoft Visual C++, 32-bit Editions 2.1
- Microsoft Visual C++, 32-bit Editions 2.2
- Microsoft Visual C++, 32-bit Editions 4.0
- Microsoft Visual C++, 32-bit Editions 4.1
- Microsoft Visual C++, 32-bit Enterprise Edition 4.2
- Microsoft Visual C++, 32-bit Enterprise Edition 5.0
- Microsoft Visual C++, 32-bit Enterprise Edition 6.0
- Microsoft Visual C++, 32-bit Professional Edition 4.2
- Microsoft Visual C++, 32-bit Professional Edition 5.0
- Microsoft Visual C++, 32-bit Professional Edition 6.0
- Microsoft Visual C++, 32-bit Learning Edition 6.0
This article was previously published under Q148455 SYMPTOMS Under the Checked build of Windows NT or a diagnostic
utility you receive an error similar to this one: BASE:
GlobalFree called with a locked object. The Checked build of Windows
NT causes a Hard-Coded breakpoint to occur, which generates a message similar
to this one: User Breakpoint called from code at:
0x77f2706f CAUSE The CSharedFile class maintains a global memory block. As
soon as an HGLOBAL is allocated by a CSharedFile object (or specified in a call
to SetHandle), it calls GlobalLock to lock this memory block.
If the
CSharedFile object is destroyed, then a call to GlobalUnlock() and GlobalFree()
will correctly unlock and free the global memory block. However, if a call to
Detach() is made to retrieve the HGLOBAL, then the handle returned is still
locked. There is no call to GlobalUnlock() made to match the call to
GlobalLock().
The memory block referenced by the HGLOBAL cannot be
moved because it has a positive reference count. Also, if an attempt is made to
free the HGLOBAL by way of a call to GlobalFree(), the symptoms given in this
article will occur. RESOLUTION After calling CSharedFile::Detach(), you can unlock the
global memory block by making a call yourself to GlobalUnlock(). Because this
workaround is dependent on the implementation of CSharedFile(), you should be
sure to use conditional compilation for this block of code as demonstrated
here:
CSharedFile file;
// Do stuff to fill in the CSharedFile
HGLOBAL hGlob = file.Detach();
#if _MFC_VER <= 0x0600
::GlobalUnlock(hGlob);
#endif
STATUS Microsoft has confirmed this to be a bug in the Microsoft
products listed at the beginning of this article. We are researching this
problem and will post new information here in the Microsoft Knowledge Base as
it becomes available.
| Modification Type: | Major | Last Reviewed: | 6/1/2005 |
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| Keywords: | kbBug KB148455 kbAudDeveloper |
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