Re: [equinox-dev] DS activation and error logging

[Stoyan Boshev <s.boshev@xxxxxxxxxxx>]

Comments inlined

Michael Furtak wrote:
> Hi all,
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> I have recently upgraded to the release candidate versions of Equinox 
> 3.5 and am seeing some unexpected behavior from DS.
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> The first question I have is in regard to component activation. In the 
> RC versions I have noticed that if an exception is thrown in the 
> activate() method, the SCR will attempt to instantiate the component 
> again, a variable number of times. As far as I can tell, this number of 
> times seems to be related to how many other bundles 
> (components/services) are activated within the framework.
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> So, for example:
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> protected void activate(ComponentContext context)
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> {
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> System.out.println(“Failing activation”);
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> throw new RuntimeException();
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> }
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> “Failing activation” will be printed once for a run configuration that 
> includes that bundle, the OSGi bundles, and nothing else. However, if a 
> number of other bundles are activated, it can appear more than once. Is 
> the SCR attempting to start this bundle repeatedly? If so, does that 
> behavior jive with the specification? This behavior is new to the 3.5 
> releases, and did not occur in 3.4.2.
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>  

This behavior is not against the DS spec. In fact it is not described 
what shall be done in such cases.
I think the current behavior is more appropriate than blacklisting the 
component and never activate it again.
Perhaps there should be a limited number of tries for activation and/or 
timeout for each subsequent activation try. But this seems like a 
feature request. Ideally this should go also as a DS spec update. I will 
post an issue to OSGi about that.

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> The second question I have is regarding the exception logging behavior 
> of DS. What has been doubly confusing about this simple example 
> situation is that I am not seeing any report about the exception thrown 
> in the activate() method. No log file is generated in the configuration 
> directory, and no stack trace is printed to the console. (I’m using the 
> –consoleLog program argument). The strange thing is that if I use a much 
> more complex run configuration with many bundles using DS, I can slip an 
> exception into the activate() method of one of them and I will see the 
> log file and console statements generated.
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> The set of Equinox jars I am using is (3.5 RC4):
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> org.eclipse.equinox.ds_1.1.0.v20090601.jar
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> org.eclipse.equinox.event_1.1.100.v20090520-1800.jar
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> org.eclipse.equinox.log_1.2.0.v20090520-1800.jar
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> org.eclipse.equinox.util_1.0.100.v20090520-1800.jar
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> org.eclipse.osgi.services_3.2.0.v20090520-1800.jar
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> org.eclipse.osgi.util_3.2.0.v20090520-1800.jar
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> org.eclipse.osgi_3.5.0.v20090520.jar
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> Program arguments are:
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> -console –consoleLog
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The DS spec requires that errors and warnings are logged by SCR via the 
LogService if available. In your configuration it is provided by the 
org.eclipse.equinox.log bundle. If your environment does not have 
LogService then you will not be able to see any errors from SCR.

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> Any thoughts or advice would be appreciated.
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> Thanks,
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> -Mike Furtak
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