dbms_pipes: Conncurrency and performance questions

I wonder if there is anyone out there who is familiar with dbms_pipes monitoring and concurrency issues.

I am working with an application which uses dbms_pipes to communicate between VB/ORACLE*GLUE front ends and a PRO*C server process. Front end processes (100-200) place requests in the pipe which are retrieved by the back-end processes.

Every now and again, the application completely stalls.

By monitoring and simuluation, we have determined that:

        Processes have very much increased "latch free" waits when performance is bad.

        Sending a message through the pipe which uses a higher value for maxpipesize (eg increases the size of the pipe) rapidly and dramatically reduces "latch free" waits and restores performance, but only temporarily. Eventually,

        I thought at first that the pipe was filling and processes were being "blocked" via latches. However we don't see any "pipe put" waits in v$session_event so it would seem that the pipe is not filling.

Does anyone have any info on pipe concurrency, throughput, contention, etc? Is anyone else using them in high throughput - high concurrency situations?

 Thanks for any help,    

 Guy          Received on Tue Dec 06 1994 - 03:13:34 CET