DOCUMENT:Q187884  09-AUG-2001  [winnt]
TITLE   :CoCreateInstance on Multiple Threads Causes Hangs or Failures
PRODUCT :Microsoft Windows NT
PROD/VER:WinNT:4.0
OPER/SYS:
KEYWORDS:kbWinNT400sp4fix

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The information in this article applies to:

 - Microsoft Windows NT Workstation version 4.0 
 - Microsoft Windows NT Server version 4.0 
 - Microsoft Windows NT Server version 4.0, Terminal Server Edition 
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SYMPTOMS
========

Calling CoCreateInstance on multiple threads at the same time causes the
computer to not respond (hang) for long periods of time. No desktop activity can
be performed during this time. PerfMon logs during the time the computer is not
responding show no signs that the computer is stressed. The idle thread has more
than 95 percent of the CPU time while the computer is not responding. This
problem was originally identified when hosting ASP pages that issue
CoCreateInstance requests. When under stress, the computer would cease
responding. CoCreateInstance requests would fail with the E_OUTOFMEMORY error
leading up to the time when the computer quits responding.

CAUSE
=====

The problem is caused by a shortage in the LPC resource pool. All threads that
request LPC pool storage are in a wait (a two-minute timeout) for a free pool
request to post that pool storage is available. Explorer.exe threads that need
LPC pool storage will also wait. Since no free pool requests come through, all
threads wait for two minutes, giving the appearance of a system hang. When the
two minute timeout expires, the pool is expanded and all threads begin running
again.


RESOLUTION
==========

To resolve this problem, obtain the latest service pack for Windows NT 4.0 or
Windows NT Server 4.0, Terminal Server Edition. For additional information,
please see the following article in the Microsoft Knowledge Base:

   Q152734 How to Obtain the Latest Windows NT 4.0 Service Pack


STATUS
======

Microsoft has confirmed this to be a problem in Windows NT 4.0 and Windows NT
Server 4.0, Terminal Server Edition. This problem was first corrected in Windows
NT 4.0 Service Pack 4.0 and Windows NT Server 4.0, Terminal Server Edition
Service Pack 4.


Additional query words: CoCreateInstance stress hang E_OUTOFMEMORY

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Keywords          : kbWinNT400sp4fix 
Technology        : kbWinNTsearch kbWinNTWsearch kbWinNTW400 kbWinNTW400search kbWinNT400search kbWinNTSsearch kbWinNTS400search kbWinNTS400 kbNTTermServ400 kbNTTermServSearch
Version           : WinNT:4.0
Hardware          : ALPHA x86
Issue type        : kbbug
Solution Type     : kbfix

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