Re: [Sqlrelay-discussion] Startup time

[David M. <dav...@fi...>]

At once time, there was a 1-second delay after starting each 
sqlr-connection daemon.  This has been removed as of version 0.47, I 
think.  So, that delay is gone now.

It can take a long time to log into Oracle though.  This is the issue 
that SQL Relay was originally designed to remedy.  In a web-app where 
each page has to log in, each web page would suffer that delay if it had 
to log directly in to Oracle rather than logging into relay and being 
handed an already-open connection.

You can do some general tuning to the machine Oracle is running on to 
make Oracle run better, and reduce the connection delay as a side 
effect, but it generally takes a second or two at best to log in, and 
usually longer.

The thing that seems to have the absolute biggest impact on Oracle 
performance, or performance for any db, is whether the db machine has 
enough physical memory.  Oracle has a million tunable parameters - 
mainly buffer sizes.  Making them larger generally improves performance, 
so people generally try to make them as large as possible, but it's 
possible to make them so large that they cause all of physical memory to 
be consumed, then you suddenly get a drastic reduction in performance.

If you're running Oracle in a VM, then there's an even worse thing that 
can happen.  If the host machine is out of physical memory and paging, 
but the VM itself isn't, then an attempt by a program running in the VM 
to load a page from what it thinks is physical memory might actually 
cause that page to have to be loaded from disk on the host.  If the OS 
running in the VM knew that it was loading the page from disk, then it 
could put the process to sleep while the I/O was occurring, but since 
the OS in the VM thinks it's loading from physical memory, the process 
won't sleep while waiting on the I/O and the VM has to do tricks, like 
insert no-ops or even put the entire VM process to sleep, or a 
combination.  At least that's my understanding of it.  Whatever is 
happening, it REALLY slows things down.

I hope this helps.

Dave
dav...@fi...

On 12/11/2012 06:31 AM, Marcus Mönnig wrote:
> Hello!
>
> Is there anything that can be done/configured to speed up the start of
> sqlrelay?
>
> A single sqlr-start against an Oracle database takes pretty exactly 10
> seconds and since I need to start 38 relays at once, this sums up to
> over 6 minutes, which is a bit long.
>
> Kind regards,
> Marcus Mönnig
>
>
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