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Posted to dev@tomcat.apache.org by bu...@apache.org on 2012/12/17 09:56:06 UTC
[Bug 54315] New: Redeploying webapp causes NullPointerException in
managerBase
https://issues.apache.org/bugzilla/show_bug.cgi?id=54315
Bug ID: 54315
Summary: Redeploying webapp causes NullPointerException in
managerBase
Product: Tomcat 7
Version: 7.0.29
Hardware: PC
OS: Linux
Status: NEW
Severity: normal
Priority: P2
Component: Catalina
Assignee: dev@tomcat.apache.org
Reporter: bfj@teamonline.dk
Classification: Unclassified
Created attachment 29775
--> https://issues.apache.org/bugzilla/attachment.cgi?id=29775&action=edit
Stacktrace
This only happends sometimes, and is hard to reproduce.
After undeploying and deploying a webapp, sometimes the webapp show an
exception at the jps's.
I've traced it down to ManagerBase.java - generateSessionId() method. It looks
like the sessionIdGenerator is null.
Attached stacktrace
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[Bug 54315] Redeploying webapp causes NullPointerException in
managerBase
Posted by bu...@apache.org.
https://issues.apache.org/bugzilla/show_bug.cgi?id=54315
Bo Frydkjær Jørgensen <bf...@teamonline.dk> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEEDINFO |NEW
--- Comment #2 from Bo Frydkjær Jørgensen <bf...@teamonline.dk> ---
Hi Mark (and others),
1. I have never seen this after startup of tomcat, only when
undeploying/deploying a webapp.
2. Yes, it happends on all requests.
3. No, a context restart does not fix it, only a restart of the tomcat fixes
it.
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[Bug 54315] Redeploying webapp causes NullPointerException in
managerBase
Posted by bu...@apache.org.
https://issues.apache.org/bugzilla/show_bug.cgi?id=54315
--- Comment #18 from Mark Thomas <ma...@apache.org> ---
(In reply to Konstantin Kolinko from comment #17)
> (In reply to Mark Thomas from comment #13)
> > re 2, I don't see how this could lead to the constant NPE issue the OP
> > reported unless deployment failed.
> I mean that it continues this way:
>
> TH2 continues shutting down the context, as it thinks that all wrappers are
> unloaded and no request processing is happening at this moment.
>
> In StandardContext.stopInternal() TH2 has done "children[i].stop();" and the
> next steps that it does are:
>
> * filterStop();
> * ((Lifecycle) manager).stop();
>
> In ManagerBase.stopInternal() it does "this.sessionIdGenerator = null;".
>
>
> TH1: It goes on with request processing and encounters that the session
> manager has been stopped and manager.sessionIdGenerator is null.
>
> This is just a theory, I have not tested it.
That would explain a small number of NPEs. I don't see how it could result in
all future requests resulting in NPEs as reported by the OP.
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[Bug 54315] Redeploying webapp causes NullPointerException in
managerBase
Posted by bu...@apache.org.
https://issues.apache.org/bugzilla/show_bug.cgi?id=54315
Mark Thomas <ma...@apache.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC|markt@apache.org |
--- Comment #9 from Mark Thomas <ma...@apache.org> ---
It is extremely rude to add someone to a cc list for a bug without their
permission. Repeat offenders will be blocked from further use of the ASF
Bugzilla system.
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[Bug 54315] Redeploying webapp causes NullPointerException in
managerBase
Posted by bu...@apache.org.
https://issues.apache.org/bugzilla/show_bug.cgi?id=54315
Operations Team <op...@teamonline.dk> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |operations@teamonline.dk
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[Bug 54315] Redeploying webapp causes NullPointerException in
managerBase
Posted by bu...@apache.org.
https://issues.apache.org/bugzilla/show_bug.cgi?id=54315
--- Comment #16 from Lorenzo <lo...@gmail.com> ---
I added some logs with at the INFO level.
I hope you can gather some information from it.
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[Bug 54315] Redeploying webapp causes NullPointerException in
managerBase
Posted by bu...@apache.org.
https://issues.apache.org/bugzilla/show_bug.cgi?id=54315
--- Comment #17 from Konstantin Kolinko <kn...@gmail.com> ---
(In reply to Mark Thomas from comment #13)
> re 2, I don't see how this could lead to the constant NPE issue the OP
> reported unless deployment failed.
>
I said:
> TH1: in StandardWrapper.allocate() checks for unloading
> TH1: in StandardWrapper.allocate() waits for synchronized block
> TH2: executes StandardWrapper.unload()
> TH1: in StandardWrapper.allocate() obtains the monitor and allocates a servlet
> Expected: TH1 should not be able to allocate one, as unloading has
> already happened.
I mean that it continues this way:
TH2 continues shutting down the context, as it thinks that all wrappers are
unloaded and no request processing is happening at this moment.
In StandardContext.stopInternal() TH2 has done "children[i].stop();" and the
next steps that it does are:
* filterStop();
* ((Lifecycle) manager).stop();
In ManagerBase.stopInternal() it does "this.sessionIdGenerator = null;".
TH1: It goes on with request processing and encounters that the session manager
has been stopped and manager.sessionIdGenerator is null.
This is just a theory, I have not tested it.
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[Bug 54315] Redeploying webapp causes NullPointerException in
managerBase
Posted by bu...@apache.org.
https://issues.apache.org/bugzilla/show_bug.cgi?id=54315
Mark Thomas <ma...@apache.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|REOPENED |RESOLVED
Resolution|--- |INVALID
--- Comment #13 from Mark Thomas <ma...@apache.org> ---
re 2, I don't see how this could lead to the constant NPE issue the OP reported
unless deployment failed.
Also re 2, unloading would benefit from being volatile. Adding a check for
unloading in loadServlet() should address the issue of allocation occurring
after unloading has started.
1, 3 & 4. Agreed.
I have applied the robustness improvements to 8.0.x for 8.0.4 and 7.0.x for
7.0.53.
I still haven't see any evidence that there is a Tomcat bug here such as an
explanation of how any of the reported problems can occur that doesn't involve
an application and/or library retaining a reference it shouldn't. Therefore, I
am returning this bug to the invalid state.
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[Bug 54315] Redeploying webapp causes NullPointerException in
managerBase
Posted by bu...@apache.org.
https://issues.apache.org/bugzilla/show_bug.cgi?id=54315
Mark Thomas <ma...@apache.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |NEEDINFO
--- Comment #1 from Mark Thomas <ma...@apache.org> ---
Hmm. An NPE there means that a session manager is being used that either has
not been started or has been stopped. Given it is hard to reproduce we will
probably have to resort to code analysis to determine what is goin on. I have a
few ideas but before I start looking harder it would be useful to have a few
more details.
1. Have you ever seen this issue after a normal start or is it only on a
restart?
2. When the NPE appears, does it happen on every request from then on or does
it happen to just a few requests during the restart?
3. If the answer to 2) is every request does a context restart fix it?
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[Bug 54315] Redeploying webapp causes NullPointerException in
managerBase
Posted by bu...@apache.org.
https://issues.apache.org/bugzilla/show_bug.cgi?id=54315
--- Comment #6 from Mark Thomas <ma...@apache.org> ---
It has been three weeks without any further information provided. If the
information has not been provided by the time of the next 7.0.x release then
this issue will be closed as WONTFIX.
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[Bug 54315] Redeploying webapp causes NullPointerException in
managerBase
Posted by bu...@apache.org.
https://issues.apache.org/bugzilla/show_bug.cgi?id=54315
--- Comment #4 from Mark Thomas <ma...@apache.org> ---
I've found and fixed one place where undeploy could go wrong (filters throwing
exceptions on destroy) and I have fixed that in trunk and 7.0.x for 7.0.35.
I'm not sure that is what is going on here though although it is probably
something very like that. I'd expect to see something in the logs during the
undeploy to indicate what has gone wrong.
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[Bug 54315] Redeploying webapp causes NullPointerException in
managerBase
Posted by bu...@apache.org.
https://issues.apache.org/bugzilla/show_bug.cgi?id=54315
Lorenzo <lo...@gmail.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|RESOLVED |REOPENED
Resolution|WONTFIX |---
--- Comment #7 from Lorenzo <lo...@gmail.com> ---
(In reply to Mark Thomas from comment #6)
> It has been three weeks without any further information provided. If the
> information has not been provided by the time of the next 7.0.x release then
> this issue will be closed as WONTFIX.
Hi,
I have the same error and I get it quite often.
I use Tomcat 7.0.50 on a 64 bit machine.
I have this log4j properties config, if you tell me how to change it to log the
error I can provide the logs.
# configure the daily rolling file appender
log4j.rootLogger=FINE, RollingAppender
# Set the priority for each package
log4j.logger.org.apache.catalina.util.LifecycleBase=FINE, RollingAppender
log4j.appender.RollingAppender=org.apache.log4j.DailyRollingFileAppender
log4j.appender.RollingAppender.File=../logs/ApplicationWeb.log
log4j.appender.RollingAppender.DatePattern='.'yyyy-MM-dd
log4j.appender.RollingAppender.layout=org.apache.log4j.PatternLayout
log4j.appender.RollingAppender.layout.ConversionPattern=[%p] %d %c %M - %m%n
The staccktrace of the error I get is:
java.lang.NullPointerException
org.apache.catalina.session.ManagerBase.generateSessionId(ManagerBase.java:807)
org.apache.catalina.session.ManagerBase.createSession(ManagerBase.java:653)
org.apache.catalina.connector.Request.doGetSession(Request.java:2956)
org.apache.catalina.connector.Request.getSession(Request.java:2320)
org.apache.catalina.connector.RequestFacade.getSession(RequestFacade.java:899)
org.apache.catalina.connector.RequestFacade.getSession(RequestFacade.java:911)
com.abovo.gc.plata.filter.AuthenticationFilter.doFilter(AuthenticationFilter.java:47)
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[Bug 54315] Redeploying webapp causes NullPointerException in
managerBase
Posted by bu...@apache.org.
https://issues.apache.org/bugzilla/show_bug.cgi?id=54315
Mark Thomas <ma...@apache.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEEDINFO |RESOLVED
Resolution|--- |WONTFIX
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[Bug 54315] Redeploying webapp causes NullPointerException in
managerBase
Posted by bu...@apache.org.
https://issues.apache.org/bugzilla/show_bug.cgi?id=54315
--- Comment #11 from Lorenzo <lo...@gmail.com> ---
Sorry,
I tought that you could be interested in the opportunity to have some debug
about the presumed error.
I will keep investigate it.
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[Bug 54315] Redeploying webapp causes NullPointerException in
managerBase
Posted by bu...@apache.org.
https://issues.apache.org/bugzilla/show_bug.cgi?id=54315
--- Comment #8 from Lorenzo <lo...@gmail.com> ---
(In reply to Mark Thomas from comment #6)
> It has been three weeks without any further information provided. If the
> information has not been provided by the time of the next 7.0.x release then
> this issue will be closed as WONTFIX.
Hi,
I have the same error and I get it quite often.
I use Tomcat 7.0.50 on a 64 bit machine.
I have this log4j properties config, if you tell me how to change it to log the
error I can provide the logs.
# configure the daily rolling file appender
log4j.rootLogger=FINE, RollingAppender
# Set the priority for each package
log4j.logger.org.apache.catalina.util.LifecycleBase=FINE, RollingAppender
log4j.appender.RollingAppender=org.apache.log4j.DailyRollingFileAppender
log4j.appender.RollingAppender.File=../logs/ApplicationWeb.log
log4j.appender.RollingAppender.DatePattern='.'yyyy-MM-dd
log4j.appender.RollingAppender.layout=org.apache.log4j.PatternLayout
log4j.appender.RollingAppender.layout.ConversionPattern=[%p] %d %c %M - %m%n
The staccktrace of the error I get is:
java.lang.NullPointerException
org.apache.catalina.session.ManagerBase.generateSessionId(ManagerBase.java:807)
org.apache.catalina.session.ManagerBase.createSession(ManagerBase.java:653)
org.apache.catalina.connector.Request.doGetSession(Request.java:2956)
org.apache.catalina.connector.Request.getSession(Request.java:2320)
org.apache.catalina.connector.RequestFacade.getSession(RequestFacade.java:899)
org.apache.catalina.connector.RequestFacade.getSession(RequestFacade.java:911)
com.abovo.gc.plata.filter.AuthenticationFilter.doFilter(AuthenticationFilter.java:47)
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[Bug 54315] Redeploying webapp causes NullPointerException in
managerBase
Posted by bu...@apache.org.
https://issues.apache.org/bugzilla/show_bug.cgi?id=54315
Lorenzo <lo...@gmail.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |loreattore@gmail.com,
| |markt@apache.org
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[Bug 54315] Redeploying webapp causes NullPointerException in
managerBase
Posted by bu...@apache.org.
https://issues.apache.org/bugzilla/show_bug.cgi?id=54315
--- Comment #15 from Lorenzo <lo...@gmail.com> ---
Created attachment 31376
--> https://issues.apache.org/bugzilla/attachment.cgi?id=31376&action=edit
the logs when the server is redeployed successfully
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[Bug 54315] Redeploying webapp causes NullPointerException in
managerBase
Posted by bu...@apache.org.
https://issues.apache.org/bugzilla/show_bug.cgi?id=54315
Mark Thomas <ma...@apache.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|REOPENED |RESOLVED
Resolution|--- |INVALID
--- Comment #10 from Mark Thomas <ma...@apache.org> ---
This is either an application bug or a bug in
com.abovo.gc.plata.filter.AuthenticationFilter that is retaining and using a
reference to a request object from a previous request rather than using the
request object for the current request.
This is not a bug in Apache Tomcat.
Further assistance is available from the Apache Tomcat users mailing list.
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[Bug 54315] Redeploying webapp causes NullPointerException in
managerBase
Posted by bu...@apache.org.
https://issues.apache.org/bugzilla/show_bug.cgi?id=54315
Mark Thomas <ma...@apache.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |NEEDINFO
--- Comment #5 from Mark Thomas <ma...@apache.org> ---
We need to track what is going on. Please add the following to you
logging.properties and then provide the section of the logs that shows the
undeploy/deploy when the error occurs.
org.apache.catalina.util.LifecycleBase.level = FINE
Note: This will slow down Tomcat start and stop but it should have minimal
impact on normal running.
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[Bug 54315] Redeploying webapp causes NullPointerException in
managerBase
Posted by bu...@apache.org.
https://issues.apache.org/bugzilla/show_bug.cgi?id=54315
--- Comment #3 from Mark Thomas <ma...@apache.org> ---
I'm still not exactly sure what is going on here but it looks like something is
going wrong with the undeploy. There have been some fixes related to failed
undeploys since 7.0.29 so it would be helpful if you could test with 7.0.34. In
the meantime, I'll keep digging.
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[Bug 54315] Redeploying webapp causes NullPointerException in
managerBase
Posted by bu...@apache.org.
https://issues.apache.org/bugzilla/show_bug.cgi?id=54315
--- Comment #14 from Lorenzo <lo...@gmail.com> ---
Created attachment 31375
--> https://issues.apache.org/bugzilla/attachment.cgi?id=31375&action=edit
the logs when I get the null pointer
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[Bug 54315] Redeploying webapp causes NullPointerException in
managerBase
Posted by bu...@apache.org.
https://issues.apache.org/bugzilla/show_bug.cgi?id=54315
Konstantin Kolinko <kn...@gmail.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|RESOLVED |REOPENED
Resolution|INVALID |---
--- Comment #12 from Konstantin Kolinko <kn...@gmail.com> ---
Lorenzo's thread on users@ for Tomcat 7.0.50:
http://marc.info/?t=139351186000004&r=1&w=2
Just some guesses
1. This should not happen, because StandardWrapperValve.invoke() takes care of
it.
If web application is being stopped while some requests are still being
processed, Tomcat logs the following message is logged like the following:
[[[
05-Mar-2014 19:59:33.701 INFO [localhost-startStop-1]
org.apache.catalina.core.StandardWrapper.unload Waiting for 1 instance(s) to be
deallocated for Servlet [jsp]
05-Mar-2014 19:59:34.701 INFO [localhost-startStop-1]
org.apache.catalina.core.StandardWrapper.unload Waiting for 1 instance(s) to be
deallocated for Servlet [jsp]
]]]
If such errors are logged,
it is explainable that other errors may follow.
Note though that the messages are logged at INFO level. Sometimes logs are
configured to skip those.
Note that
1) StandardContext.stopInternal() stops its wrappers (=children) before all
other subcomponents
2) The issue is reported as occurring in a filter. Invoking the filter chain is
performed in StandardWrapperValve.invoke() in between wrapper.allocate() and
wrapper.deallocate() calls. As such, it should be protected by the same
allocation counter that protects the servlet that is being called here.
2. In StandardWrapper.allocate()
I think the following code:
[[[
if (unloading)
throw new ServletException
(sm.getString("standardWrapper.unloading", getName()));
]]]
would better be copied inside synchronized (this) {} block below.
The 'unloading' field may change while we are waiting to get into synchronized
block. That is if there is the following sequence of events:
TH1: in StandardWrapper.allocate() checks for unloading
TH1: in StandardWrapper.allocate() waits for synchronized block
TH2: executes StandardWrapper.unload()
TH1: in StandardWrapper.allocate() obtains the monitor and allocates a servlet
Expected: TH1 should not be able to allocate one, as unloading has already
happened.
3. I think the o.a.c.core.StandardContext.paused field would better be marked
volatile.
The redeployment happens in background thread, but the field is read in
CoyoteAdapter.postParseRequest() in a request processing thread. It might read
a stale value.
(It would not cause this NullPointerException as reported here. It can cause
"503 Unavailable" response from StandardWrapperValve.invoke() or
ServletException("standardWrapper.unloading") from StandardWrapper.allocate()).
4. In StandardWrapper.invoke() the check for "if
(!context.getState().isAvailable())" is done before "wrapper.allocate()" call.
There is small time window between those checks.
(It would not cause this NullPointerException as reported here. It can cause
ServletException("standardWrapper.unloading") from StandardWrapper.allocate()).
Anyway, in this case I do not see how it could be done better.
The LifecycleBase.state field is already marked as 'volatile'. Asking for it
twice seems like a waste. The checks in allocate() should protect here/
========
Resume:
for 1.: Beware if logging is configured to skip INFO messages.
Of course, if context is stopped before request processing on it completes,
some things are expected to fail. Tomcat waits here, the timeout is
configurable. It is a tradeoff. An infinite wait is usually undesirable.
See "unloadDelay" setting on Context. The default value is 2 seconds.
http://tomcat.apache.org/tomcat-7.0-doc/config/context.html
for 2. and 3.: These can be improved.
for 4.: OK, nothing to do.
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