Return-Path: Delivered-To: apmail-db-derby-user-archive@www.apache.org Received: (qmail 2757 invoked from network); 30 Aug 2006 20:21:52 -0000 Received: from hermes.apache.org (HELO mail.apache.org) (209.237.227.199) by minotaur.apache.org with SMTP; 30 Aug 2006 20:21:52 -0000 Received: (qmail 34806 invoked by uid 500); 30 Aug 2006 20:21:51 -0000 Delivered-To: apmail-db-derby-user-archive@db.apache.org Received: (qmail 34510 invoked by uid 500); 30 Aug 2006 20:21:50 -0000 Mailing-List: contact derby-user-help@db.apache.org; run by ezmlm Precedence: bulk list-help: list-unsubscribe: List-Post: List-Id: Reply-To: "Derby Discussion" Delivered-To: mailing list derby-user@db.apache.org Received: (qmail 34499 invoked by uid 99); 30 Aug 2006 20:21:50 -0000 Received: from asf.osuosl.org (HELO asf.osuosl.org) (140.211.166.49) by apache.org (qpsmtpd/0.29) with ESMTP; Wed, 30 Aug 2006 13:21:50 -0700 X-ASF-Spam-Status: No, hits=1.3 required=10.0 tests=RCVD_NUMERIC_HELO,SPF_HELO_PASS,SPF_PASS X-Spam-Check-By: apache.org Received-SPF: pass (asf.osuosl.org: domain of gcaddu-derby-user@m.gmane.org designates 80.91.229.2 as permitted sender) Received: from [80.91.229.2] (HELO ciao.gmane.org) (80.91.229.2) by apache.org (qpsmtpd/0.29) with ESMTP; Wed, 30 Aug 2006 13:21:49 -0700 Received: from root by ciao.gmane.org with local (Exim 4.43) id 1GIWXZ-0004hV-Uq for derby-user@db.apache.org; Wed, 30 Aug 2006 22:20:10 +0200 Received: from 204.245.215.66 ([204.245.215.66]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Wed, 30 Aug 2006 22:20:01 +0200 Received: from mark.hellkamp by 204.245.215.66 with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Wed, 30 Aug 2006 22:20:01 +0200 X-Injected-Via-Gmane: http://gmane.org/ To: derby-user@db.apache.org From: Mark Hellkamp Subject: Concurrent access problems? Date: Wed, 30 Aug 2006 20:10:02 +0000 (UTC) Lines: 24 Message-ID: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Complaints-To: usenet@sea.gmane.org X-Gmane-NNTP-Posting-Host: main.gmane.org User-Agent: Loom/3.14 (http://gmane.org/) X-Loom-IP: 204.245.215.66 (Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.0.6) Gecko/20060728 Firefox/1.5.0.6) Sender: news X-Virus-Checked: Checked by ClamAV on apache.org X-Spam-Rating: minotaur.apache.org 1.6.2 0/1000/N We are trying to use Derby embedded in our web application but are running into some serious resource problems when processing concurrent requests. When we are performing load testing on the application we are experiencing serious slowdowns, even when running only a few concurrent threads. We are noticing that the process handle count on our application keeps growing during our tests, until the machine becomes completely unresponsive. We have isolated the problem to Derby and I have moved Derby out of the application process by running it in Network Server mode. In this configuration we can see that the handle count on the Derby process will grow as we add more concurrent threads accessing the application. Looking at the handles for the Derby process, it appears that the number of Semaphores keeps increasing. I'm not sure if this is normal or this indicates a problem, but it seems a bit suspicious. I also completely swapped out Derby with MySql to verify that the application was not at fault (we are using Spring + Hibernate for data access). Under MySQl we did not see a significant performance degradation with multiple threads, and the handle count remained fairly steady on the database. Does Derby have problems with concurrent access? Our tests are doing read only queries against the database so read/write contention should not be a problem. I am extremely perplexed by this problem. Anyone have any ideas? Regards, Mark