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[Pljava-dev] pl/java and concurrency
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* [Pljava-dev] pl/java and concurrency
@ 2012-04-28 22:02  
  0 siblings, 1 reply; 2+ messages in thread

From:  @ 2012-04-28 22:02 UTC (permalink / raw)

i'm looking a pl/java as a possible implementation language for a trigger function.

the trigger is going to need to do a couple of selects, build an xml string and then issue an http request.
it has the potential to be rather busy.

i understand the reason why entry points need to be statics, but i'd like to understand how pl/java
deals with concurrency. could someone please outline how this works?

the solution will be running on amazon ec2 linux instances, postgresql 9.1.3. the installed jdk is
openjdk 1.6

thanks,
   richard
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* [Pljava-dev] pl/java and concurrency
@ 2012-04-29 12:37  
  parent: 
  0 siblings, 0 replies; 2+ messages in thread

From:  @ 2012-04-29 12:37 UTC (permalink / raw)

Hi Richard,

Each connection in PostgreSQL runs in a process of its own. It's not a 
multi threaded server architecture. This means that each connection will 
have a JVM of its own which means that there's no real concurrency.

If code inside a trigger spawns multiple threads that in turn performs 
database accesses using the internal PL/Java jdbc driver, then PL/Java 
will synchronize those calls and only allow one at a time. It has to be 
that way since they all share the same connection (and the same 
transaction).

HTH,
Thomas Hallgren


On 2012-04-29 00:02, Welty, Richard wrote:
>
> i'm looking a pl/java as a possible implementation language for a 
> trigger function.
>
> the trigger is going to need to do a couple of selects, build an xml 
> string and then issue an http request.
> it has the potential to be rather busy.
>
> i understand the reason why entry points need to be statics, but i'd 
> like to understand how pl/java
> deals with concurrency. could someone please outline how this works?
>
> the solution will be running on amazon ec2 linux instances, postgresql 
> 9.1.3. the installed jdk is
> openjdk 1.6
>
> thanks,
>    richard
>
>
>
> _______________________________________________
> Pljava-dev mailing list
> Pljava-dev at pgfoundry.org
> http://pgfoundry.org/mailman/listinfo/pljava-dev

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