locked JAR files on undeploy - one possible cause

[markt-2]

As locked JARs on undeploy is a popular topic, I thought I would share a
recent discovery. If you read your log4j configuration file from a JAR,
the JAR will end up locked, preventing a clean undeploy.

Full details are here:
https://issues.apache.org/bugzilla/show_bug.cgi?id=47465

Mark


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[awarnier]

Mark Thomas wrote:
> As locked JARs on undeploy is a popular topic, I thought I would share a
> recent discovery. If you read your log4j configuration file from a JAR,
> the JAR will end up locked, preventing a clean undeploy.
>
> Full details are here:
> https://issues.apache.org/bugzilla/show_bug.cgi?id=47465
>
Mark,
is this specifically a log4j-linked problem, or does this affect any
other properties/configuration files loaded from JARs ?

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[markt-2]

André Warnier wrote:

> Mark Thomas wrote:
>> As locked JARs on undeploy is a popular topic, I thought I would share a
>> recent discovery. If you read your log4j configuration file from a JAR,
>> the JAR will end up locked, preventing a clean undeploy.
>>
>> Full details are here:
>> https://issues.apache.org/bugzilla/show_bug.cgi?id=47465
>>
> Mark,
> is this specifically a log4j-linked problem, or does this affect any
> other properties/configuration files loaded from JARs ?

It will affect any file loaded from a JAR via a URL where there isn't a
call to URLConnection.setUseCaches(false).

Another workaround may be to use a ContextListener and call
URLConnection.setDefaultUseCaches(false) although that may have
performance side effects. One assumes these things are cached for a
reason although I haven't taken the time to look at the source to figure
out what the impact, if any, would be.

Mark



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[awarnier]

Mark Thomas wrote:

> André Warnier wrote:
>> Mark Thomas wrote:
>>> As locked JARs on undeploy is a popular topic, I thought I would share a
>>> recent discovery. If you read your log4j configuration file from a JAR,
>>> the JAR will end up locked, preventing a clean undeploy.
>>>
>>> Full details are here:
>>> https://issues.apache.org/bugzilla/show_bug.cgi?id=47465
>>>
>> Mark,
>> is this specifically a log4j-linked problem, or does this affect any
>> other properties/configuration files loaded from JARs ?
>
> It will affect any file loaded from a JAR via a URL where there isn't a
> call to URLConnection.setUseCaches(false).
>

To this self-confessed dummy, this sounds as if, even though files
loaded from JARs may not be so frequent, but given the thousands of
Tomcat's out there, it ought to affect quite a few installations.
Might it also be a reason why some Tomcats do not seem able to shutdown
properly when told ?
(Don't spend time answering this if I'm talking nonsense.)


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[markt-2]

André Warnier wrote:

> Mark Thomas wrote:
>> André Warnier wrote:
>>> Mark Thomas wrote:
>>>> As locked JARs on undeploy is a popular topic, I thought I would
>>>> share a
>>>> recent discovery. If you read your log4j configuration file from a JAR,
>>>> the JAR will end up locked, preventing a clean undeploy.
>>>>
>>>> Full details are here:
>>>> https://issues.apache.org/bugzilla/show_bug.cgi?id=47465
>>>>
>>> Mark,
>>> is this specifically a log4j-linked problem, or does this affect any
>>> other properties/configuration files loaded from JARs ?
>>
>> It will affect any file loaded from a JAR via a URL where there isn't a
>> call to URLConnection.setUseCaches(false).
>>
> To this self-confessed dummy, this sounds as if, even though files
> loaded from JARs may not be so frequent, but given the thousands of
> Tomcat's out there, it ought to affect quite a few installations.

Yep. Hence my e-mail. For the record, I found it looking into an Grails
issue [1].

> Might it also be a reason why some Tomcats do not seem able to shutdown
> properly when told ?

It will only cause an undeploy to fail. It won't interfere with a full
shutdown.

Mark

[1] http://jira.codehaus.org/browse/GRAILS-2544


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