DOCUMENT:Q149616  30-JUL-2001  [visualc]
TITLE   :FIX: Developer Studio May Hang When Debug Session Starts/Ends
PRODUCT :Microsoft C Compiler
PROD/VER:4.00
OPER/SYS:
KEYWORDS:kbide kbVC kbVC400bug kbGrpDSToolskbbuglist kbfixlist

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The information in this article applies to:

 - Microsoft Visual C++, version 4.0 
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SYMPTOMS
========

When starting or ending a debugging session, Developer Studio hangs (doesn't
respond to user input).

CAUSE
=====

The problem occurs because there is a large amount of text to display in the
Output window, and Developer Studio is in a state where it is unable to display
it.

Here are two scenarios where this problem will occur:

 - The problem can occur when you start debugging an application that implicitly
   links to a large number of DLLs. You implicitly link to a DLL by linking with
   the import library for the DLL. The problem has been known to occur with an
   application that implicitly links to more than 100 DLLs.

   In this scenario, the debugger is attempting to output a message similar to
   this one:

   LDR: LdrpMapDll Relocating: Base Name MYDLL.dll

   This message indicates that the operating system is relocating the DLL to load
   it at an address other than its default base address.

 - The problem can also occur when an application sends out a large number of
   debug messages as it exits. These could be messages from the application
   itself, from the C run-time (CRT) library, or from the MFC libraries. This
   has been known to occur when an application has a large number of memory
   leaks that are reported by the MFC or the CRT libraries as the application
   exits.

RESOLUTION
==========

For the first scenario, you could use the /BASE linker option when building the
DLLs with which the application implicitly links. The /BASE option allows you to
set a preferred base address for a .dll or .exe file. If you set a different
base address for each DLL, the operating system will not need to relocate them
when loading them, and Developer Studio will not need to send a message to
indicate this. Using the /BASE option avoids the problem and allows the
application to load more efficiently regardless of whether it is being debugged
or not. For more information about the /BASE option, please refer to the online
documentation.

For second scenario, if the application being debugged is using MFC, you can
temporarily turn off tracing output using the MFC Tracer application, If the
application does not use MFC and the debug messages are coming from the CRT
library, then you could use the _CrtSetReportMode and _CrtSetReportFile
functions in the application. These functions could be used to redirect the
messages to a file instead of the Developer Studio Output window. For more
information on the CRT debug functions, please refer to the online
documentation.

STATUS
======

Microsoft has confirmed this to be a bug in the Microsoft products listed at the
beginning of this article. This problem has been corrected in version 4.0.


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

Even though this bug has been fixed in version 4.1, there may be a noticeable
delay when you start a debugging session when the application implicitly links
to a large number of DLLs.

Additional query words: 4.00

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Keywords          : kbide kbVC kbVC400bug kbGrpDSTools kbbuglist kbfixlist
Technology        : kbVCsearch kbVC400 kbAudDeveloper
Version           : 4.00
Issue type        : kbbug
Solution Type     : kbfix

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