[Spread-users] Buffers

Theo Schlossnagle jesus at omniti.com
Tue May 29 10:46:57 EDT 2001

On Tuesday, May 29, 2001, at 10:04  AM, Xabier Vázquez Gallardo wrote:
> Custom code.

Okay.  You amy not want to buffer so much.  The reason for buffering in 
most applications is to reduce disk I/O.  You will  have no disk I/O 
with Spread, so a more steady stream of messages will probably be more 
healthy for all apps involved.

>>> sometimes get disconnected from spread. How can I increse the spread
>>> buffer?
>>> Changing
>>> #define         MAX_SESSION_MESSAGES    1000
>>> in spread_params.h?
> Can I change it into 10000? How will this change affect to spread?

You actually want to ask this message on the Spread list.  One of the 
Spread authors will answer it better than I could.  (I Cced the list so 
they can just chime in :-)

I _think_ you can increase it as high as you like, but it allows on 
group member to be up to MAX_SESSION_MESSAGES behind another member.  
This is not good in most cases, though it may not matter in your logging 
scenario.  There could be other undesirable effects of raising this too 
high that I am not aware of.  Jonathan?  Yair?

I find it interesting that your application is reading to slow.  If you 
are just reading from Spread, you must be handling the messages 
synchronously (like writing them to disk).  I would suggest using an 
advanced I/O strategy like kaio, aio, non-blocking I/O or multithreaded 
programming to reduce the dependency of the reading events on the 
writing events.  "spreadlogd" doesn't do this because it assumes it is 
being used with mod_log_spread which doesn't burst :-)

Theo Schlossnagle
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