Re: overhead of ZEO connection

Hi,

Thanks for reply. If pool size is 8 then is following true ?

In application; there are some long running(may run more than a hour) 
threads. there are 8 such threads
these 8 long running threads get all available 8 connections in pool

There are some short duration threads also, which read/write in database. 
These short duration threads won't get connection until at least one of the 
long running thread does not release connection.

Best Regards,
Sanjay Rao

On Friday, 6 May 2016 19:32:21 UTC+5:30, Tres Seaver wrote:
>
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> On 05/06/2016 09:33 AM, Sanjay Rao wrote: 
>
> > In this post I want to understand the overhead of creating database 
> > connections in a zope application what is overhead of creating a new 
> > connection to ZEO ? 
> > 
> > which one is recommended ? 
> > 
> > - Create a connection - Use this connection for each transaction 
> > commit (one transaction commit could be bounded into one function) - 
> > Close connection when application terminates 
> > 
> > OR 
> > 
> > - Create one separate connection for each transaction commit - Commit 
> > transaction - Close connection ..... 
>
> You definitely don't want to *destroy* the connection at transaction 
> boundaries:  each connection holds a cache (in RAM) of objects retrieved 
> from the database.  The `ZODB.DB.DB` object, which holds onto the 
> storage, also maintains a connection pool.  The usual pattern would be: 
>
> - ------------------------- %< ------------------------- 
> # At startup 
> from ZODB.DB import DB 
> from ZEO.ClientStorage impport ClientStorage 
>
> storage = ClientStoraget((192.168.1.200, 9876)) 
> db = DB(storage) 
>
> # Whenever you need a connection 
> conn = db.open()  # checks it out of the pool 
> root = conn.root() 
>
> # Use the root object to do work 
> try: 
>     do_something_with(root) 
> except Exception: 
>     transaction.abort() 
>     raise 
> else: 
>     transaction.commit() 
>
> conn.close()  # return 'conn' to the pool 
> - ------------------------- %< ------------------------- 
>
> Zope follows this pattern for each HTTP request it serves.  Hope that 
> helps, 
>
>
> Tres. 
> - -- 
> =================================================================== 
> Tres Seaver          +1 540-429-0999          [email protected] 
> <javascript:> 
> Palladion Software   "Excellence by Design"    http://palladion.com 
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