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

[Brendon Price]

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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