Q281446: FIX: Access Violation with std::map::erase or std::set::erase

Article: Q281446
Product(s): Microsoft C Compiler
Version(s): 6.0 SP4
Operating System(s): 
Keyword(s): kbCPPonly kbSTL kbVC600 kbVC600fix kbDSupport kbVS600sp5fix
Last Modified: 03-MAY-2001

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The information in this article applies to:

- The C Run-Time (CRT), included with:
   - Microsoft Visual C++, 32-bit Editions, version 6.0 SP4 
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SYMPTOMS
========

When you call the std::map::erase and std::set::erase member functions at the
same time from multiple threads, an access violation may be generated.

STATUS
======

Microsoft has confirmed this to be a bug in the Microsoft products listed at the
beginning of this article.

This bug has been fixed in Microsoft Visual Studio 6.0 Service Pack 5 (SP5).

To download service pack 5, see the Visual Studio Product Updates page on the
following Microsoft Web site at:

  http://support.microsoft.com/support/servicepacks/VS/6.0/default.asp?sd=msdn

MORE INFORMATION
================

The bug was introduced in Visual Studio 6.0 Service Pack 4 (SP4) when the bug
that is documented in Q248477 was corrected:

For additional information, click the article number below to view the article in
the Microsoft Knowledge Base:

  Q248477 FIX: Deadlock Using STL Map or Set in Multithreaded Application

Steps to Reproduce Behavior
---------------------------

The following sample code demonstrates the bug:

  // Test.cpp
  // Compiler option needed: /MT or /MD
  #include <windows.h>
  #include <set>

  typedef std::set<int> TestSet;

  DWORD WINAPI Worker( LPVOID )
  {
  TestSet set;
  int g_cIters =4;

      for( int i=0; i < g_cIters; i++ )
      {
          int r = rand();
          int j;

          for( j=0; j < r; j++ )
          {
          set.insert( j );
          }

          for( j=0; j < r; j++ )
          {
              TestSet::iterator it = set.find( j );
              set.erase( it );
          }
      } 

      return 0;
  }     
        
  void main()
  {
     
      int cThreads = 10;

      HANDLE  aThreads[10];

      for( int i=0; i < cThreads; i++ )
      {
          aThreads[i] = CreateThread( NULL, 0, Worker, NULL, 0, NULL );
      }

      WaitForMultipleObjects( cThreads, aThreads, TRUE, INFINITE );
  } 

Additional query words:

======================================================================
Keywords          : kbCPPonly kbSTL kbVC600 kbVC600fix kbDSupport kbVS600sp5fix 
Technology        : kbVCsearch kbAudDeveloper kbCRT
Version           : :6.0 SP4
Issue type        : kbbug
Solution Type     : kbfix

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