Re: dll loading time performance

From:
"Ben Voigt [C++ MVP]" <rbv@nospam.nospam>
Newsgroups:
microsoft.public.vc.language
Date:
Mon, 18 Feb 2008 08:29:39 -0600
Message-ID:
<#q8U0pjcIHA.4936@TK2MSFTNGP03.phx.gbl>

When loading of a DLL takes a long time, it can be due to many
reasons: * The DLL is really huge, so the time is spent reading the hard
disk.
 * The DLL has a very complex DllMain that takes a long time to
execute * The DLL has many dependencies that need to be loaded as well.
 * Windows needs to rebase the DLL
 * The DllMain allocates a huge amount of memory so windows needs to
re-arrange its memory layout (trashing, paging)

There might be more reasons. But as long as the reason is not the
busy CPU than you won't gain much performance effect when loading the
DLL in a separate thread. All threads share the same hard disk,
memory manager, process etc. And I guess the main application still
needs to wait until all DLLs have been loaded before it can proceed.


Only if the process is performing independent I/O (i.e. over a network)
would a separate thread help.

However if the database access or dependent DLLs are loaded over a network,
then multithreading could give huge benefits by allowing multiple requests
to be sent at the same time.

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