[opencms-dev] Resolution to deadlocks in getting JDBC connections?

[James George]

Hi Brendon,

Thanks for that even though its good news and bad.

Just wanting to confirm; has this been identified as a problem in the 
OpenCMS connection pooling code, the java.sql.DriverManager, the Oracle 
JDBC driver or the interaction of all three?  If the first or last 
options, is there a development branch being worked on that tries to 
rework the code in question?

Upgrading the version of OpenCMS is an option for us, but changing the 
version of the database is likely to be more tricky.

Thanks in advance.

James

Brendon Price wrote:

> James,
> 
> We ended up rebuilding a specific version of OpenCMS 5.0.0 that replaced
> the data layer to avoid this problem. Not a simple work around
> unfortunately.
> 
> Our solution will only work with an Oracle 9 database as it uses the built
> in Oracle connection pooling mechanism.
> 
> That is why we never published it as a fix.
> 
> Regards
> Brendon
> 
> -----Original Message-----
> From: opencms-dev-admin at opencms.org
> [mailto:opencms-dev-admin at opencms.org]On Behalf Of James George
> Sent: Wednesday, 28 January 2004 1:23 p.m.
> To: opencms-dev at opencms.org
> Subject: [opencms-dev] Resolution to deadlocks in getting JDBC
> connections?
> 
> 
> Hi all,
> 
> OpenCMS 5.0.0
> 9iAS/OC4J 9.0.3.1
> Oracle RDBMS 8.1.7.4
> all on HPUX
> 
> I'm assisting in trouble shooting an OpenCMS implementation on an Oracle 
> 9iAS application server and we are seeing deadlocks occurring between 
> the genericsql thread using java.sql.DriverManager.getDrivers() and 
> ApplicationServerThread-X using 
> com.opencms.dbpool.CmsPool.getConnection() (see below for excerpts from 
> thread traces).
> 
> I've searched the mailing list archives and found references to this 
> issue, but couldn't find any reference to a fix or suitable workaround. 
>   Do any exist?  I checked the history for 5.0.1, but there was no 
> reference to this issue.
> 
> At the moment this is causing intermittent failures in a production 
> system, so if there are any pointers or suggestions (other than a 
> nightly restart) anyone can make to help us mitigate this issue, it 
> would be greatly appreciated.
> 
> Thanks in advance!
> 
> James
> 
> Deadlocked threads:
> 
> Found one Java-level deadlock:
> =============================
> "ApplicationServerThread-25":
>    waiting to lock monitor 0x18a73c (object 0x4f314438, a java.util.Stack),
>    which is held by "genericsql"
> "genericsql":
>    waiting to lock monitor 0x18a7b0 (object 0x49e07240, a java.lang.Class),
>    which is held by "ApplicationServerThread-25"
> 
> Java stack information for the threads listed above:
> ===================================================
> "ApplicationServerThread-25":
>      at com.opencms.dbpool.CmsPool.getConnection(CmsPool.java:217)
>      - waiting to lock <0x4f314438> (a java.util.Stack)
>      at com.opencms.dbpool.CmsPool.connect(CmsPool.java:206)
>      at com.opencms.dbpool.CmsDriver.connect(CmsDriver.java:107)
>      at java.sql.DriverManager.getConnection(DriverManager.java:512)
>      - locked <0x49e07240> (a java.lang.Class)
>      at java.sql.DriverManager.getConnection(DriverManager.java:193)
>      - locked <0x49e07240> (a java.lang.Class)
>      at 
> com.opencms.file.genericSql.CmsDbAccess.readUser(CmsDbAccess.java:10136)
>      at 
> com.opencms.file.genericSql.CmsResourceBroker.readUser(CmsResourceBroker.jav
> a:6478)
>      at com.opencms.file.CmsRequestContext.init(CmsRequestContext.java:172)
>      at com.opencms.file.CmsObject.init(CmsObject.java:2200)
>      at com.opencms.core.OpenCms.initUser(OpenCms.java:896)
>      at 
> com.opencms.core.OpenCmsHttpServlet.initUser(OpenCmsHttpServlet.java:473)
>      at 
> com.opencms.core.OpenCmsHttpServlet.doGet(OpenCmsHttpServlet.java:304)
>      at javax.servlet.http.HttpServlet.service(HttpServlet.java:740)
>      at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
>      at 
> com.evermind.server.http.ResourceFilterChain.doFilter(ResourceFilterChain.ja
> va:65)
>      at oracle.security.jazn.oc4j.JAZNFilter.doFilter(JAZNFilter.java:283)
>      at 
> com.evermind.server.http.ServletRequestDispatcher.invoke(ServletRequestDispa
> tcher.java:566)
>      at 
> com.evermind.server.http.ServletRequestDispatcher.forwardInternal(ServletReq
> uestDispatcher.java:306)
>      at 
> com.evermind.server.http.HttpRequestHandler.processRequest(HttpRequestHandle
> r.java:767)
>      at 
> com.evermind.server.http.AJPRequestHandler.run(AJPRequestHandler.java:166)
>      at 
> com.evermind.server.http.AJPRequestHandler.run(AJPRequestHandler.java:72)
>      at 
> EDU.oswego.cs.dl.util.concurrent.PooledExecutor$Worker.run(PooledExecutor.ja
> va:803)
>      at java.lang.Thread.run(Thread.java:536)
> "genericsql":
>      at java.sql.DriverManager.getDrivers(DriverManager.java:321)
>      - waiting to lock <0x49e07240> (a java.lang.Class)
>      at oracle.jdbc.driver.OracleDriver.connect(OracleDriver.java:317)
>      at com.opencms.dbpool.CmsPool.createConnection(CmsPool.java:338)
>      at com.opencms.dbpool.CmsPool.createConnections(CmsPool.java:320)
>      at com.opencms.dbpool.CmsPool.run(CmsPool.java:188)
>      - locked <0x4f314438> (a java.util.Stack)
> 
> Found 1 deadlock.
> 

-- 
-----------------------------------------------
James George - Consultant
Oracle Corporation          Ph:  +61 8 94267200
Perth, Western Australia    Fax: +61 8 93215175

"I like nonsense; it wakes up the brain cells."
- Dr. Seuss
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