Hi Tomcat developers,
Below is a discussion that has been ongoing on the log4j-dev list. We are
trying to figure out why the log4j jar file is locked after a webapp is
removed from Tomcat using the Tomcat manager app. Basically, all jar
resources in a webapp are let go after a manager remove except for the
log4j jar (within WEB-INF/lib). In order to remove the lock on the jar,
Tomcat has to be shut down completely, not just have the webapp
removed. We had thought we had found the reason for it (static
initializers) but that didn't turn out to be reproducible. At this point,
we are a bit perplexed.
Can any Tomcat developers tell us if there are any classloading issues with
Tomcat that might cause Tomcat to hold onto a jar file in the WEB-INF/lib
directory after the app has been removed via the manager app? Could it be
commons-logging that is holding onto it? Any help would be appreciated.
BTW, could cross-post responses to [EMAIL PROTECTED]?
thanks,
Jake
Date: Mon, 07 Oct 2002 07:12:30 -0500
To: Log4J Developers List [EMAIL PROTECTED]
From: Jacob Kjome [EMAIL PROTECTED]
Subject: RE: FW: log4j.jar locked by Tomcat even after remove/undeploy
I'll pose this question to the tomcat-user and/or tomcat-dev list sometime
today. Maybe they can help us out on this.
Jake
At 09:39 PM 10/6/2002 -0700, you wrote:
I swear, I reproduced this multiple times before I posted my earlier
message. When I just tried it, the problem did not happen. Ack, this is
frustrating!
What else can we use to attack this problem? Is there some way to tell what
is active in the JVM that is preventing the jar from being unloaded?
-Mark
-Original Message-
From: Jacob Kjome [mailto:[EMAIL PROTECTED]]
Sent: Saturday, October 05, 2002 6:46 PM
To: [EMAIL PROTECTED]
Subject: Re: FW: log4j.jar locked by Tomcat even after remove/undeploy
Hi Mark,
I am now subscribed to the log4j-dev list.
I tested all the scenarios that you described, but I never found
static_test.jar to be locked except for when the application is installed
(as expected). When I remove the app, the only thing that is locked is
log4j-1.2.6.jar. I can delete everything other than that.
It is really curious that it locks for you and doesn't for me???
The thing
is in Barracuda, the open source Presentation Framework, where the
Log4jInit and Log4jApplicationWatch come from, there are a number
of places
that use static initializers and I find no locking issues with the
Barracuda libraries.
Has anyone else reproduced Mark's results?
BTW, mark, when you use Log4jInit, you can just have the param for the
FileApender look something like this:
param name=File value=${barracuda.log.home}/main.log /
Basically, Log4jInit gerates a system variable based on the name of the
webapp context. Here is how it works:
[name of webapp context].log.home
So, a webapp at:
http://localhost:8080/barracuda/
would create a system variable named barracuda.log.home
A webapp at:
http://localhost:8080/myapp/
would create a system variable named myapp.log.home
Just look for the file main.log in WEB-INF/logs directory of you
webapp. If the logs directory doesn't exist, it will be
created. So, it
doesn't matter where your webapp is deployed from as long as it isn't
deployed directly from a .war file, you will never have to bother setting
the path. It will be found automatically.
If you want to override the path where the log file gets written,
just set
the log4j-log-home parameter for the Log4jInit servlet in the web.xml
such as:
param-namelog4j-log-home/param-name
param-valueD:\my\logging\path/param-value
Nice and flexible, heh?
Jake
At 10:52 AM 10/4/2002 -0700, you wrote:
The discussion has moved to the log4j-dev email list, but I don't know if
you are currently subscribed to that list, so I am forwarding it to you.
Please let me know what you find.
-Mark
-Original Message-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]
Sent: Thursday, October 03, 2002 11:18 PM
To: [EMAIL PROTECTED]
Subject: RE: log4j.jar locked by Tomcat even after remove/undeploy
Ceki Jake,
I have done some more tests, and I believe very strongly that
the problem is
in Tomcat. I have enclosed my entire webapp (I am still using the one I
made last night, with some modifications, and you will need to add the
log4j-1.2.6.jar to your deployment; I did not include it in the
enclosed zip
file).
Here is what I do, you tell me what you think:
1) I created 2 new classes, org.womacknet.StaticTest and
org.womacknet.NonStaticTest. StaticTest has a static initializer defined
and 2 static members. NonStaticTest does not have a static
intitializer and
only an instance member. I compiled these files and put them
into their own
static_test.jar, which I placed into the WEB-INF
