Re: Singletons in Geronimo

[David Blevins]

On Oct 28, 2009, at 10:12 AM, Quintin Beukes wrote:
Hey,

Busy compiling. WIll let you know how the new changes work.

So, what's the basic idea behind these changes? I had a quick look at
the patches. Though I don't know enough about Geronimo and would need
to carefully step through the code to understand the change.

About the simplest way I can think to describe it is that the startup  
process was like this:

1. start EjbModuleGBean -- OpenEJB creates CoreDeploymentInfo objects  
and deploys them into the containers.
2. start EjbDeploymentGBean -- Grabs the CoreDeploymentInfo, finishes  
JNDI setup, installs itself into the CoreDeploymentInfo.

The problem is that "deploys them into containers" can involve JNDI  
lookups and those require step 2 to have completed.  Previously the  
only beans that could actually get the chance to do a lookup on  
"container.deploy()" was MDBs and that was bascially because the  
MdbContainer would hook the bean up to the JMS Resource Adapter and  
messages could start flowing in immediately -- even before we reached  
step 2.  So the workaround that was added (not by me) was to put that  
synchronized block in so that lookups would wait till step 2  
completed.  That works fine for MDBs as they all get processed in  
other threads so those "incoming message" threads would just hold for  
a moment while we continued to start the app.  With Singletons you get  
a deadlock for very obvious reasons; a lookup in step 1 will cause the  
startup thread to wait for itself to complete step 2.  Obviously that  
will never happen.

So I basically reworked the code so that 2 happens before 1 and  
removed that synchronized block.  I more or less worked around the  
fact that EjbDeploymentGBean needs a reference to the not yet created  
CoreDeploymentInfo object by using a java.util.concurrent.Future  
object and some smarter code in the GeronimoThreadContextListener.  So  
the initialization we were doing in step 2 now happens on the fly the  
first time the bean is invoked, whenever that is.

Hope that makes any kind of sense :)

-David



Quintin Beukes



On Wed, Oct 28, 2009 at 3:17 PM, David Blevins  
<david.blev...@visi.com> wrote:

On Oct 28, 2009, at 12:02 AM, David Jencks wrote:

Did you build all of geronimo?  I wonder if this is caused by  
something
like trying to run a plugin packaged under java6 on java5, which  
doesn't
always work.

Right, built from the root with an 'rm -r
~/.m2/repository/org/apache/geronimo' for good measure.

will try a build here overnight...

Great.  Nice to have a second pair of eyes.

-David


On Oct 27, 2009, at 10:06 PM, David Blevins wrote:

The changes look good, though I seem to be running into an issue  
creating
the car for the wadi stuff.  Not sure what might be happening and  
looking
for ideas.

Here's the -e output:

[INFO] [car:package]
[INFO] Packaging module configuration:
/Users/dblevins/work/geronimo-22-branch/plugins/openejb/openejb- 
clustering-wadi/target/work/plan.xml
[INFO]  GBean references are not using proxies
[INFO]  ClassLoading behaviour has changed.  The Original  
Classloading
mode is in effect.  If you are experiencing a problem
you can change the behaviour by specifying
-DXorg.apache.geronimo.kernel.config.MPCLSearchOption= property.   
Specify
="safe" to revert to the original behaviour.  This is a temporary  
change
until we decide whether or not to make it
permanent for the 2.0 release
[INFO] Started deployer:
org.apache.geronimo.framework/geronimo-gbean-deployer/2.2- 
SNAPSHOT/car
[INFO]  The Strict Manifest Classpath processing mode is in effect.
This option can be altered by specifying
-DXorg.apache.geronimo.deployment.LenientMFCP=true|false
Specify ="true" for more lenient processing such as ignoring  
missing jars
and references that are not spec compliant.
[INFO]
------------------------------------------------------------------------
[ERROR] BUILD ERROR
[INFO]
------------------------------------------------------------------------
[INFO] could not package plugin

Embedded error: Unable to create configuration for deployment
[INFO]
------------------------------------------------------------------------
[INFO] Trace
org.apache.maven.lifecycle.LifecycleExecutionException: could not  
package
plugin
       at
org 
.apache 
.maven 
.lifecycle 
.DefaultLifecycleExecutor 
.executeGoals(DefaultLifecycleExecutor.java:584)
       at
org 
.apache 
.maven 
.lifecycle 
.DefaultLifecycleExecutor 
.executeGoalWithLifecycle(DefaultLifecycleExecutor.java:500)
       at
org 
.apache 
.maven 
.lifecycle 
.DefaultLifecycleExecutor 
.executeGoal(DefaultLifecycleExecutor.java:479)
       at
org 
.apache 
.maven 
.lifecycle 
.DefaultLifecycleExecutor 
.executeGoalAndHandleFailures(DefaultLifecycleExecutor.java:331)
       at
org 
.apache 
.maven 
.lifecycle 
.DefaultLifecycleExecutor 
.executeTaskSegments(DefaultLifecycleExecutor.java:292)
       at
org 
.apache 
.maven 
.lifecycle 
.DefaultLifecycleExecutor.execute(DefaultLifecycleExecutor.java: 
142)
       at  
org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:336)
       at org.apache.maven.DefaultMaven.execute(DefaultMaven.java: 
129)
       at org.apache.maven.cli.MavenCli.main(MavenCli.java:301)
       at sun.reflect.NativeMethodAccessorImpl.invoke0(Native  
Method)
       at
sun 
.reflect 
.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
       at
sun 
.reflect 
.DelegatingMethodAccessorImpl 
.invoke(DelegatingMethodAccessorImpl.java:25)
       at java.lang.reflect.Method.invoke(Method.java:592)
       at
org.codehaus.classworlds.Launcher.launchEnhanced(Launcher.java:315)
       at org.codehaus.classworlds.Launcher.launch(Launcher.java: 
255)
       at
org.codehaus.classworlds.Launcher.mainWithExitCode(Launcher.java: 
430)
       at org.codehaus.classworlds.Launcher.main(Launcher.java:375)
Caused by: org.apache.maven.plugin.MojoExecutionException: could  
not
package plugin
       at
org 
.apache 
.geronimo.mavenplugins.car.PackageMojo.execute(PackageMojo.java: 
212)
       at
org 
.apache 
.maven 
.plugin 
.DefaultPluginManager.executeMojo(DefaultPluginManager.java:453)
       at
org 
.apache 
.maven 
.lifecycle 
.DefaultLifecycleExecutor 
.executeGoals(DefaultLifecycleExecutor.java:559)
       ... 16 more
Caused by: org.apache.geronimo.common.DeploymentException: Unable  
to
create configuration for deployment
       at
org 
.apache 
.geronimo 
.deployment 
.DeploymentContext.createTempConfiguration(DeploymentContext.java: 
151)
       at
org 
.apache 
.geronimo 
.deployment.DeploymentContext.<init>(DeploymentContext.java:131)
       at
org 
.apache 
.geronimo 
.deployment.DeploymentContext.<init>(DeploymentContext.java:111)
       at
org 
.apache 
.geronimo 
.deployment 
.service 
.ServiceConfigBuilder 
.buildConfiguration(ServiceConfigBuilder.java:227)
       at
org 
.apache 
.geronimo 
.deployment 
.service 
.ServiceConfigBuilder 
.buildConfiguration(ServiceConfigBuilder.java:199)
       at
org.apache.geronimo.deployment.Deployer.deploy(Deployer.java:257)
       at sun.reflect.NativeMethodAccessorImpl.invoke0(Native  
Method)
       at
sun 
.reflect 
.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
       at
sun 
.reflect 
.DelegatingMethodAccessorImpl 
.invoke(DelegatingMethodAccessorImpl.java:25)
       at java.lang.reflect.Method.invoke(Method.java:592)
       at
org 
.apache 
.geronimo 
.gbean 
.runtime 
.ReflectionMethodInvoker.invoke(ReflectionMethodInvoker.java:34)
       at
org 
.apache 
.geronimo.gbean.runtime.GBeanOperation.invoke(GBeanOperation.java: 
130)
       at
org 
.apache 
.geronimo.gbean.runtime.GBeanInstance.invoke(GBeanInstance.java: 
850)
       at
org 
.apache.geronimo.kernel.basic.BasicKernel.invoke(BasicKernel.java: 
237)
       at
org 
.apache 
.geronimo 
.mavenplugins.car.PackageMojo.invokeDeployer(PackageMojo.java:483)
       at
org 
.apache 
.geronimo 
.mavenplugins.car.PackageMojo.buildPackage(PackageMojo.java:309)
       at
org 
.apache 
.geronimo.mavenplugins.car.PackageMojo.execute(PackageMojo.java: 
209)
       ... 18 more
Caused by: org.apache.geronimo.kernel.config.LifecycleException:  
load of
org.apache.geronimo.configs/openejb-clustering-wadi/2.2-SNAPSHOT/ 
car failed
       at
org 
.apache 
.geronimo 
.kernel 
.config 
.SimpleConfigurationManager 
.loadConfiguration(SimpleConfigurationManager.java:316)
       at
org 
.apache 
.geronimo 
.deployment 
.DeploymentConfigurationManager 
.loadConfiguration(DeploymentConfigurationManager.java:115)
       at
org 
.apache 
.geronimo 
.kernel 
.config 
.SimpleConfigurationManager 
.loadConfiguration(SimpleConfigurationManager.java:277)
       at
org 
.apache 
.geronimo 
.deployment 
.DeploymentConfigurationManager 
.loadConfiguration(DeploymentConfigurationManager.java:111)
       at
org 
.apache 
.geronimo 
.deployment 
.DeploymentContext.createTempConfiguration(DeploymentContext.java: 
148)
       ... 34 more
Caused by:  
org.apache.geronimo.kernel.config.InvalidConfigException:
Error starting configuration gbean
org.apache.geronimo.configs/clustering/2.2-SNAPSHOT/car
       at
org 
.apache 
.geronimo 
.kernel 
.config 
.SimpleConfigurationManager.load(SimpleConfigurationManager.java: 
341)
       at
org 
.apache 
.geronimo 
.deployment 
.DeploymentConfigurationManager 
.load(DeploymentConfigurationManager.java:119)
       at
org 
.apache 
.geronimo 
.kernel 
.config 
.SimpleConfigurationManager 
.loadConfiguration(SimpleConfigurationManager.java:302)
       ... 38 more
Caused by:  
org.apache.geronimo.kernel.config.InvalidConfigException:
Unable to deserialize GBeanState in classloader:
[org.apache.geronimo.kernel.config.MultiParentClassLoader
id=org.apache.geronimo.configs/clustering/2.2-SNAPSHOT/car]
       at
org 
.apache 
.geronimo 
.kernel 
.config.SerializedGBeanState.loadGBeans(SerializedGBeanState.java: 
137)
       at
org 
.apache 
.geronimo 
.kernel 
.config.SerializedGBeanState.getGBeans(SerializedGBeanState.java: 
64)
       at
org 
.apache 
.geronimo 
.kernel.config.ConfigurationData.getGBeans(ConfigurationData.java: 
177)
       at
org 
.apache 
.geronimo.kernel.config.Configuration.<init>(Configuration.java: 
295)
       at
org 
.apache 
.geronimo 
.kernel 
.config 
.SimpleConfigurationManager.load(SimpleConfigurationManager.java: 
337)
       ... 40 more
Caused by: java.lang.NullPointerException
       at
org.apache.geronimo.gbean.GBeanData.setAttribute(GBeanData.java: 
148)
       at
org.apache.geronimo.gbean.GBeanData 
$V0Externalizable.readExternal(GBeanData.java:336)
       at
org.apache.geronimo.gbean.GBeanData.readExternal(GBeanData.java: 
282)
       at
org 
.apache 
.geronimo 
.kernel 
.config.SerializedGBeanState.loadGBeans(SerializedGBeanState.java: 
124)
       ... 44 more
[INFO]
------------------------------------------------------------------------
[INFO] Total time: 1 minute 14 seconds
[INFO] Finished at: Tue Oct 27 22:02:24 PDT 2009
[INFO] Final Memory: 58M/104M
[INFO]
------------------------------------------------------------------------