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Q236797: THREAD_BLOCKING Error After WinAPPCCleanup Issued

Article: Q236797
Product(s): Microsoft SNA Server
Version(s): WINDOWS:3.0,3.0 SP1,3.0 SP2,3.0 SP3,3.0 SP4,4.0,4.0 SP1,4.0 SP2
Operating System(s): 
Keyword(s): kbsna300sp1 kbsna300sp2 kbsna300sp3 kbsna300sp4 sna4 kbsna400sp1 kbsna400sp2
Last Modified: 08-MAY-2002

-------------------------------------------------------------------------------
The information in this article applies to:

- Microsoft SNA Server, versions 3.0, 3.0 SP1, 3.0 SP2, 3.0 SP3, 3.0 SP4, 4.0, 4.0 SP1, 4.0 SP2 
-------------------------------------------------------------------------------


SYMPTOMS
========

An APPC or CPI-C application may receive the following error message when it
issues a TP_STARTED call that informs the APPC library that the TP (Transaction
Program) is starting:

  Primary Return Code = F006 (AP_THREAD_BLOCKING)

The following is an excerpt of a SNA Server APPC API trace that captures the
failing TP_STARTED call:

APPC  TP_STARTED request
APPC  
APPC  Type:Sync                                  VerbID:0001C000
APPC  
APPC  ---- Verb Parameter Block at address 0EF40000 ----
APPC  14000000 00000000 00000000 00000000     <................>
APPC  00000000 00000000 00000000 C3D7C9C3     <............CPIC>
APPC  6DC4C5C6 C1D3E36D E3D72020 20202040     <mDEFALTmTP     @>
APPC  40404040 40404040 40404040 40404040     <@@@@@@@@@@@@@@@@>
APPC  40404040 40404040 40404040 40404040     <@@@@@@@@@@@@@@@@>
APPC  40404040 40404040 40404040              <@@@@@@@@@@@@    >
APPC  --------------------------------------------------------------------------------
APPC  TP_STARTED response, result = THREAD_BLOCKING
APPC  
APPC  Type:Sync                                  VerbID:0001C000
APPC  
APPC  ---- Verb Parameter Block at address 0EF40000 ----
APPC  14000000 F0060000 00000000 00000000     <....0...........>
APPC  00000000 00000000 00000000 C3D7C9C3     <............CPIC>
APPC  6DC4C5C6 C1D3E36D E3D72020 20202040     <mDEFALTmTP     @>
APPC  40404040 40404040 40404040 40404040     <@@@@@@@@@@@@@@@@>
APPC  40404040 40404040 40404040 40404040     <@@@@@@@@@@@@@@@@>
APPC  40404040 40404040 40404040              <@@@@@@@@@@@@    >

If a CPI-C application is being used when this occurs, the following error
message is returned by the CPI-C library after it receives the THREAD_BLOCKING
error from the APPC library:

  Primary Return Code = 20 (CM_PRODUCT_SPECIFIC_ERROR)

NOTE: There might be other reasons for getting a PRODUCT_SPECIFIC_ERROR(20) that
are not necessarily related to this article. Further reasons for getting a
PRODUCT_SPECIFIC_ERROR(20) can be found in Microsoft Knowledge Base articles by
searching for "CM_PRODUCT_SPECIFIC_ERROR".

This problem can occur when an APPC or CPI-C application has previously called
WinAPPCCleanup or WinCPICCleanup to deregister the application from the APPC or
CPI-C library. If the application subsequently calls WinAPPCStartup or
WinCPICStartup to reregister the application, the next APPC or CPI-C call may
fail with the THREAD_BLOCKING error.

CAUSE
=====

This problem occurs because the APPC library is not properly clearing the
internal IS_BLOCKING flag when WinAPPCCleanup is called. The IS_BLOCKING flag is
used by the APPC library to determine whether another APPC blocking call is
already outstanding on the thread that a next APPC call is being issued on.

This problem has only been reported when the APPC or CPI-C application is
designed to issue multiple WinAPPCStartup/WinAPPCCleanup or
WinCPICStartup/WinCPICCleanup sequences for each process. WinAPPCStartup or
WinCPICStartup should only be issued when the process (that is, application)
starts. WinAPPCCleanup or WinCPICCleanup should only be issued when the process
is terminating. They should not be issued for each thread that starts or ends
within the process.

RESOLUTION
==========

A supported fix is now available from Microsoft, but it is only intended to
correct the problem described in this article and should be applied only to
systems experiencing this specific problem.

To resolve this problem, contact Microsoft Product Support Services to obtain the
fix. For a complete list of Microsoft Product Support Services phone numbers and
information on support costs, please go to the following address on the World
Wide Web:

  http://support.microsoft.com/default.aspx?scid=fh;EN-US;CNTACTMS

NOTE: In special cases, charges that are normally incurred for support calls may
be canceled, if a Microsoft Support Professional determines that a specific
update will resolve your problem. Normal support costs will apply to additional
support questions and issues that do not qualify for the specific update in
question.

The English version of this fix should have the following file attributes or
later:

+--------------------------------+
| File name   | Date     | Time  | 
+--------------------------------+
| Wappc32.dll | xx/xx/xx | xx:xx | 
+--------------------------------+

NOTE: Date and time information will be provided as soon as it becomes
available.


NOTE: Because of file dependencies, the most recent fix that contains the above
files may also contain additional files.




WORKAROUND
==========

Modify the APPC or CPI-C application such that it only calls the
WinAPPCStartup/WinAPPCCleanup or WinCPICStartup/WinCPICCleanup sequence once for
each process startup or termination.

STATUS
======

Microsoft has confirmed this to be a problem in Microsoft SNA Server versions
3.0, 3.0 SP1, 3.0 SP2, 3.0 SP3, 3.0 SP4, 4.0, 4.0 SP1, 4.0 SP2.

Additional query words:

======================================================================
Keywords          : kbsna300sp1 kbsna300sp2 kbsna300sp3 kbsna300sp4 sna4 kbsna400sp1 kbsna400sp2 
Technology        : kbAudDeveloper kbSNAServSearch kbSNAServ300 kbSNAServ400 kbSNAServ300SP3 kbSNAServ300SP1 kbSNAServ400SP1 kbSNAServ400SP2 kbSNAServ300SP2 kbSNAServ300SP4
Version           : WINDOWS:3.0,3.0 SP1,3.0 SP2,3.0 SP3,3.0 SP4,4.0,4.0 SP1,4.0 SP2
Issue type        : kbbug
Solution Type     : kbfix

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

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