Re: FW: Java Memory Issue while Loading Postgres library

On 29/04/2010 8:48 PM, A.Bhattacharya@sungard.com wrote:

> Your understanding is slightly incorrect. Actually we required to uses a
> special library from postgres.

That mystery library being? From "postgres"? Do you mean a library 
supplied by the PostgreSQL project its self? Libpq? If not, what?

C'mon, specifics. Please. Try to read your message after you have 
written it while pretending you are somebody who does not work with your 
code and does not know the things you know about it. Try to notice 
assumptions and clarify them.

> For this we write a wrapper around the
> library and composed a dll out of it (which uses ECPG to communicate to
> postgres). From the application front (Java) we make a JDBC call to
> postgres function.  This postgres function then makes call to the dll.

This does not make sense. Your earlier mail said that the DLL is loaded 
into the Java runtime.

How does a "postgres function" make a call to a DLL running in the JRE? 
You can't make a call from the postgresql backend to code on a client 
connected to ecpg.

Please be SPECIFIC. What is a "postgres function?" How does it "make a 
call to the dll?" Etc. Provide links to PostgreSQL and Java 
documentation for the APIs you use, use the precise terms for those 
APIs, and generally be SPECIFIC and DETAILED. Post diagrams or code 
samples if you have to!

> But the strange thing we observed that at runtime, somehow the execution
> of dll is attached with java.exe. In other words, when we monitor the
> performance of the application we realized that the execution of dll is
> consuming java heap memory and is shown as a thread in java.exe process.
> We expected that it should be linked with postgres.exe.

Ah, ok, so you are TRYING to load code a C extension to PostgreSQL into 
the server backend?

If so, why are you using ECPG? Or are you in fact *not* using ECPG, but 
the PostgreSQL backend extension interface?

How is the dll "shown as a thread in [the] java.exe process" ? Using a 
Java debugger attached to the JRE? Using Process Explorer or a C-level 
debugger examining the loaded DLL list of the JRE? Using the Java 
monitoring APIs?

I really do not understand what you are doing, or what you are trying to 
do. I doubt anybody can help you without a much more detailed and 
specific explanation of what you're doing.

I think it'd be a really good idea for you to write a minimalist test 
case for this and post it. Either you'll figure out what's wrong in the 
process of making the test case, or you'll have something to post that 
people can play with to see what you are trying to do.

--
Craig Ringer