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Q164913: Access Violations or Memory Leak May Occur with Tracing Enabled

Article: Q164913
Product(s): Microsoft SNA Server
Version(s): WINDOWS:3.0
Operating System(s): 
Keyword(s): kbnetwork
Last Modified: 13-JUN-2001

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The information in this article applies to:

- Microsoft SNA Server, version 3.0 
-------------------------------------------------------------------------------

This article describes the following problems that were found in SNA
Server 3.0 and corrected:

1. Enabling SNA Server tracing may cause a process to encounter an access
  violation.


2. A memory leak may occur when SNA Server tracing is enabled.


3. Link service internal tracing is not fully implemented.


SYMPTOMS
========

1. Enabling SNA Server tracing may cause a process to encounter an access
  violation.

  SYMPTOMS

  When you have enabled SNA Server tracing using the SNATRACE tool, the process
  that is being traced (for example, SNA Server, SNA Print Service, SnaBase, or
  link services) may encounter an access violation (AV). If you generate a
  Drwtsn32.log file, the following failures may occur:

  

  Exception number: c0000005 (access violation)

  Function: MSVCRT!rmtmp
  FAULT ->779f8bc7 803f00           cmp     byte ptr [edi],0x0

  -or-

  

  Exception number: c0000005 (access violation)

  Function: MSVCRT!_vsnprintf+0x34


  -or-

  

  Exception number: 80000003 (hardcoded breakpoint)

  function: DbgBreakPoint
  FAULT ->77f75d64 cc               int     3


  CAUSE

  The tracing code incorrectly handles a string buffer, which may lead to an
  access violation. Also, under some timing conditions, if two processes
  attempt to initialize tracing at the same time, an access violation may
  occur.

2. A memory leak may occur when SNA Server tracing is enabled.

  SYMPTOMS

  Enabling SNA Server tracing may lead to an internal memory leak, causing the
  server to eventually run out of virtual memory. This was observed by setting
  the trace file size to 10 MB and enabling full tracing on SNA Server, the SNA
  Print Service, and SNA Application APPC API tracing.

  CAUSE

  This problem may occur when the disk I/O cannot keep up with trace creation.
  Memory keeps growing until the system runs out of virtual memory. The
  solution is to limit the maximum size of the trace buffer pool, which by
  default is the same size as the multiple of the trace file size chosen in
  SNATRACE. For example, if the trace file size is 1 MB, (1,000,000, the
  default), with internal, message and API tracing enabled, the maximum trace
  buffer pool is 3 x 1 MB = 3 MB.

  You can use the following registry setting to define the maximum trace buffer
  pool size:

  HKEY_LOCAL_MACHINE/SOFTWARE/Microsoft/SnaServer/CurrentVersion/Traces/ 
  MemoryBufferSize: REG_DWORD: <value>

  NOTE: The MemoryBufferSize value must be manually created. It is not created
  by Setup when SNA Server is installed.


3. Link service tracing is not fully implemented.

  SYMPTOMS

  When enabling link service full internal tracing using SNATRACE, third- party
  link trace statements that use the TRACEx macros are not traced to the trace
  files.

  CAUSE

  The TRACEx macro statements were not converted to use the new SNA Server 3.0
  tracing functions.

RESOLUTION
==========

To resolve these problems, obtain the hotfix mentioned below. The updated
modules are:

  <Snaroot>\System\Snatrc.dll<BR/>
  <Snaroot>\System\Dbgtrace.dll<BR/>
  <Snaroot>\System\Snalink.dll

STATUS
======

Microsoft has confirmed this to be a problem in SNA Server version 3.0. This
problem was corrected in the latest Microsoft SNA Server 3.0 U.S. Service Pack.
For information on obtaining the service pack, query on the following word in
the Microsoft Knowledge Base (without the spaces):

  S E R V P A C K

Additional query words: prodsna snatrace dr watson

======================================================================
Keywords          : kbnetwork 
Technology        : kbAudDeveloper kbSNAServSearch kbSNAServ300
Version           : WINDOWS:3.0
Issue type        : kbbug
Solution Type     : kbfix

=============================================================================

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