Re: [Proxool-developer] Connection release latency when using proxool with PostgreSQL

[Jean-Henry B. <ber...@ne...>]

I redid the tests in verbose mode and I notice that at init time I get 
the usual lines like:

4220 [Prototyper] DEBUG org.logicalcobwebs.proxool.globexplorer_0  - 
000000 (00/24/00) - Connection #24 (719f1f) created to achieve minimum 
of 30 = AVAILABLE -> 
jdbc:postgresql://pogo:5434/gex_runtime:user=postgres;password=post.gres 
(185ad79) by thread Prototyper

There are 30 of these (as I said the min number of conns is 30) - 
nothing unusual here.

The weird part comes after that: when I do a server request (which 
usually asks for around 4 connections
from proxool) no lines like these appear (which would mean, I guess, 
that no new connections are
created by proxool) but doing netstat I notice that the number of 
connections is N+4 now, and the
number of active ones remains N - the others are in TIME_WAIT mode and 
are cleaned when the
sweeper kicks in.
Then the question would be: what's with these additional connections I see?
(in time, if I do a stress test, the number of connections raises to 
hundreds or even thousands, but the
pattern remains: the active ones are as many as I expect and the bulk 
are connections in TIME_WAIT
state)

Thanks,
Jean


Bill Horsman wrote:

>Hi Jean,
>
>On Thu, 2003-12-11 at 00:16, Jean-Henry Berevoescu wrote:
>
>  
>
>>The traces are not showing anything unusual, but I noticed another
>>thing:
>>- I start with minumumConnectionCount set to, say, 30. Proxool is
>>correctly
>>building 30, but the first time I need a connection it builds another
>>one, and
>>another one and so on, every time a need a connection from the pool.
>>So it looks like the reusability is not working.
>>Again, it was working all right with Informix, but not with
>>PostgreSQL.
>>    
>>
>
>I'd like to see more of the log to find out what's going on there. It
>should show those initial 30 connections being built. And then it will
>show what happens when you ask for your first connection to use. We can
>then see whether it is reusing one of those initial 30 or making a new
>one.
>
>  
>
>>987 [Prototyper] DEBUG org.logicalcobwebs.proxool.globexplorer_0  -
>>org.postgresql.Driver does not support getHoldability. Proxool doesn't
>>mind.
>>988 [Prototyper] DEBUG org.logicalcobwebs.proxool.globexplorer_0  -
>>org.postgresql.Driver does not support setHoldability. Proxool doesn't
>>mind.
>>    
>>
>[snip]
>  
>
>>What exactly "Holdability" means? I noticed I have it with Informix,
>>but not here.
>>    
>>
>
>It's part of the JDBC API, but not all Drivers support it. Like the log
>says, Proxool doesn't mind either way. You'll find that your Informix
>driver does support it whilst your Postgresql one doesn't.
>
>  
>
>>Also, how one can programatically set the connection to be readOnly? I
>>always use it as readOnly in what I try to do here and I noticed
>>proxool is setting it to default = false.
>>    
>>
>
>Proxool is simply remembering the readOnly state of new connections. The
>default state is false (that is, writable). That is how the connections
>are supplied from the Postgresql Driver. Proxool resets all these states
>to their original values when you return a connection to the pool.
>Otherwise, if you changed something it would remain at that new value
>when you asked for another connection and that might not be what you
>want. So: every time you ask Proxool for a connection it comes in the
>sames state as when it arrived, fresh from the Postgresql Driver.
>
>Regards,
>Bill Horsman
>
>
>
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