Hi Craig, Sorry for creating confusion. Let me (I work with Ambarish, the original author of the mail) try to be more specific now. We have a library (written in C) which helps us in doing phonetic based name search. We want to use this library inside a postgres DB function. To achieve this we wrote a small C code (we referred as wrapper class) which uses the library. This C code is an ECPG which is bundled as a dll and placed in postgres's lib dir. The original postgres function is supposed to be called from a java program using JDBC. And the postgres function should call the C function of the wrapper class. At runtime we observed that when the postgres DB function calls the C function of the wrapper class (in the dll), the java heap memory start increasing and reached to the max level resulted in crashing of JVM. Then we commented out the call to ECPG C function from postgres DB function and realized that everything went well. We were surprised why the loading and execution of the ECPG is taking JVM memory. Ideally it should use the postgres.exe memory and CPU utilization. We observed all these using windows task manager. I hope this will help you in understanding our problem. Thanks and Regards, Ashish Arya -----Original Message----- From: pgsql-general-owner@xxxxxxxxxxxxxx [mailto:pgsql-general-owner@xxxxxxxxxxxxxx] On Behalf Of Craig Ringer Sent: Thursday, April 29, 2010 6:34 PM To: Bhattacharya, A Cc: pgsql-general@xxxxxxxxxxxxxx Subject: Re: FW: Java Memory Issue while Loading Postgres library On 29/04/2010 8:48 PM, A.Bhattacharya@xxxxxxxxxxx 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 -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
