Oracle-L: shutdown abort not advised on NT, memory probs

From: <emopierc_at_pacbell.net>
Date: Thu, 25 Jul 2002 17:23:20 -0800
Message-ID: <F001.004A2F4F.20020725172320@fatcity.com>

Doc ID: Note:46001.1
l
Bulletin
Type: BULLETIN
Status: PUBLISHED
Content Type: TEXT/PLAIN
Creation Date: 14-JAN-1998
Last Revision Date: 11-APR-2002

Purpose

This note explains how Oracle interacts with Windows NT's memory architecture, for addition information about NT's memory architecture see [NOTE:46053.1] ....

e) How session memory is released & thread termination consequences

When a users session completes successfully it deallocates its memory using the Win32 API call "VirtualFree" with the MEM_DECOMMIT | MEM_RELEASE allocation flags. After all allocations have been freed the stack is also released, leaving the Oracle processes address space free of reference to the completed session.

If a users session terminates unexpectedly it will not release the memory it has allocated, the allocated pages will remain in the Oracle processes address space until the process exits. Unexpected termination may occur if a users session if forced to terminate for one of the following reasons :

Shutdown abort.
Alter session kill session.
Oracle command line utility orakill.
Oracle Administration assistant for Windows : kill session.
Other utilities that can kill threads in processes.

Oracle Support Services recommends customers minimize the use of the above commands, in particular the shutdown abort command. When shutdown abort is run its calls the Win32 API "TerminateThread" for each users session, which kills the thread without releasing its memory. On systems with many users a large percentage of the 2GB address space of the Oracle process will become inaccessible, ultimately causing allocation problems when Oracle is next started. The only way to release this memory is to stop and start the Oracle Service (e.g. OracleServiceORCL).

....

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Received on Thu Jul 25 2002 - 20:23:20 CDT