DOCUMENT:Q98416  30-JUL-2001  [lanman]
TITLE   :DosOpen Thread Blocked Pending DosWaitNmPipe
PRODUCT :Microsoft LAN Manager
PROD/VER:
OPER/SYS:
KEYWORDS:

======================================================================
SUMMARY
=======

DosOpen() local call threads become blocked if a remote pipe does not open
pending a DosWaitNmPipe() in a different thread. This is by design in OS/2 and
is easily worked around.

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

Set the ulTIMEOUT parameter of DosWaitNmPipe to a small value that is an
acceptable postponement for other I/O--maybe 2 seconds--then put the
DosWaitNmPipe in a loop. The DosWaitNmPipe now, in effect, "waits forever"
(unless you want to limit the loop instance), but every 2 seconds other I/O from
threads within the same process are serviced.

OS/2 serializes I/O at the process level, which creates (essentially) a queue of
I/O requests per process. If two threads within the same process issue I/O calls
to the operating system, the first one (longest time in queue) becomes the
DosWaitNmPipe, and the second becomes the DosOpen. The operating system must
complete processing the DosWaitNmPipe before it can entertain the DosOpen.

This behavior is not present in NT, as NT serializes I/O per thread, not per
process.

Additional query words: 2.10 2.1 2.10a 2.1a 2.20 2.2

======================================================================
Keywords          :  

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

THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS
PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND.  MICROSOFT DISCLAIMS
ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES
OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.  IN NO
EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR
ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL,
CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF
MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE
POSSIBILITY OF SUCH DAMAGES.  SOME STATES DO NOT ALLOW THE EXCLUSION
OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES
SO THE FOREGOING LIMITATION MAY NOT APPLY.

Copyright Microsoft Corporation 2001.