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Posted to dev@tomcat.apache.org by Romain Manni-Bucau <rm...@gmail.com> on 2021/01/12 16:49:11 UTC
"Missing" break in listenerStart?
Hi all,
I suspect it is intended but if so I wonder if it needs some toggle to
disable that behavior: is the fact to not break when a listener (start)
fails intended? ([1])
An ASF friend hit that with 2 listeners and second one was failling after
first one failed because it was depending on it.
Since this is not uncommon I wonder if it should get a break once ok=false
(issue can be listenerStop which should probably be independent of start
chain behavior since some listener only impl it) or if we should have a
flag in StandardContext to stop at first start failure.
Anything already thought on it?
[1]
https://github.com/apache/tomcat/blob/master/java/org/apache/catalina/core/StandardContext.java#L4669
Romain Manni-Bucau
@rmannibucau <https://twitter.com/rmannibucau> | Blog
<https://rmannibucau.metawerx.net/> | Old Blog
<http://rmannibucau.wordpress.com> | Github <https://github.com/rmannibucau> |
LinkedIn <https://www.linkedin.com/in/rmannibucau> | Book
<https://www.packtpub.com/application-development/java-ee-8-high-performance>
Re: "Missing" break in listenerStart?
Posted by Romain Manni-Bucau <rm...@gmail.com>.
Le mer. 13 janv. 2021 à 15:42, Konstantin Kolinko <kn...@gmail.com>
a écrit :
> Hi!
>
> ср, 13 янв. 2021 г. в 17:04, Romain Manni-Bucau <rm...@gmail.com>:
> >
> > Drafted https://github.com/apache/tomcat/pull/400 in regards of that
> topic.
> >
>
> Looks good thus far.
> Several notes:
>
> 1. Maybe others disagree, but I am OK with the default for
> "exitOnFirstListenerFailure" property being changed to "true".
>
> It is a rare use case, and I think that it is safe to fail early. The
> web application will fail to start anyway.
>
Any (easy) way to rerun the TCK to validate this does not break anything
before?
>
> 2. A better name?
>
> I do not like "exit**", because Tomcat does not exit here. It does not
> call "System.exit()" or anything like that. It is just a single web
> application that fails to start.
>
> Maybe something like "abortOnFirstListenerFailure".
>
> (There is org.apache.catalina.startup.EXIT_ON_INIT_FAILURE system
> property that really forces Tomcat as a whole to shut down. Thus
> "exit" is used in its name.)
>
We can also reverse it like "alwaysInitializeAllContextListeners", can be a
way to make it more explicit.
>
> 3. The attribute has to be added to the JMX configuration file,
> java/org/apache/catalina/core/mbeans-descriptors.xml
>
Will do once we all agree on a name.
>
> 4. The attribute has to be documented in the Configuration Reference,
> webapps/docs/config/context.xml
>
The same I guess ;).
>
> 5. Looking for other similar listeners and callbacks.
>
> E.g. ServletContainerInitializers
>
> for (Map.Entry<ServletContainerInitializer, Set<Class<?>>>
> entry :
> initializers.entrySet()) {
> try {
> entry.getKey().onStartup(entry.getValue(),
> getServletContext());
> } catch (ServletException e) {
> log.error(sm.getString("standardContext.sciFail"), e);
> ok = false;
> break;
> }
> }
>
There is already a break there so no need of any update I guess?
>
> Looking at implementations of org.apache.catalina.LifecycleListener -
> they are OK.
> (Those listeners are called notified via
> "org.apache.catalina.util.LifecycleBase.fireLifecycleEvent()". That
> method does not catch exceptions and thus fails early.)
>
> Best regards,
> Konstantin Kolinko
>
> ---------------------------------------------------------------------
> To unsubscribe, e-mail: dev-unsubscribe@tomcat.apache.org
> For additional commands, e-mail: dev-help@tomcat.apache.org
>
>
Re: "Missing" break in listenerStart?
Posted by Konstantin Kolinko <kn...@gmail.com>.
Hi!
ср, 13 янв. 2021 г. в 17:04, Romain Manni-Bucau <rm...@gmail.com>:
>
> Drafted https://github.com/apache/tomcat/pull/400 in regards of that topic.
>
Looks good thus far.
Several notes:
1. Maybe others disagree, but I am OK with the default for
"exitOnFirstListenerFailure" property being changed to "true".
It is a rare use case, and I think that it is safe to fail early. The
web application will fail to start anyway.
2. A better name?
I do not like "exit**", because Tomcat does not exit here. It does not
call "System.exit()" or anything like that. It is just a single web
application that fails to start.
Maybe something like "abortOnFirstListenerFailure".
(There is org.apache.catalina.startup.EXIT_ON_INIT_FAILURE system
property that really forces Tomcat as a whole to shut down. Thus
"exit" is used in its name.)
3. The attribute has to be added to the JMX configuration file,
java/org/apache/catalina/core/mbeans-descriptors.xml
4. The attribute has to be documented in the Configuration Reference,
webapps/docs/config/context.xml
5. Looking for other similar listeners and callbacks.
E.g. ServletContainerInitializers
for (Map.Entry<ServletContainerInitializer, Set<Class<?>>> entry :
initializers.entrySet()) {
try {
entry.getKey().onStartup(entry.getValue(),
getServletContext());
} catch (ServletException e) {
log.error(sm.getString("standardContext.sciFail"), e);
ok = false;
break;
}
}
Looking at implementations of org.apache.catalina.LifecycleListener -
they are OK.
(Those listeners are called notified via
"org.apache.catalina.util.LifecycleBase.fireLifecycleEvent()". That
method does not catch exceptions and thus fails early.)
Best regards,
Konstantin Kolinko
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Re: "Missing" break in listenerStart?
Posted by Romain Manni-Bucau <rm...@gmail.com>.
Drafted https://github.com/apache/tomcat/pull/400 in regards of that topic.
Romain Manni-Bucau
@rmannibucau <https://twitter.com/rmannibucau> | Blog
<https://rmannibucau.metawerx.net/> | Old Blog
<http://rmannibucau.wordpress.com> | Github <https://github.com/rmannibucau> |
LinkedIn <https://www.linkedin.com/in/rmannibucau> | Book
<https://www.packtpub.com/application-development/java-ee-8-high-performance>
Le mar. 12 janv. 2021 à 23:51, Rémy Maucherat <re...@apache.org> a écrit :
> On Tue, Jan 12, 2021 at 5:49 PM Romain Manni-Bucau <rm...@gmail.com>
> wrote:
>
> > Hi all,
> >
> > I suspect it is intended but if so I wonder if it needs some toggle to
> > disable that behavior: is the fact to not break when a listener (start)
> > fails intended? ([1])
> >
> > An ASF friend hit that with 2 listeners and second one was failling after
> > first one failed because it was depending on it.
> >
> > Since this is not uncommon I wonder if it should get a break once
> ok=false
> > (issue can be listenerStop which should probably be independent of start
> > chain behavior since some listener only impl it) or if we should have a
> > flag in StandardContext to stop at first start failure.
> >
> > Anything already thought on it?
> >
>
> For all other subcomponents of the context, the behavior is: set ok to
> false, log the error and continue. It should stay that way. However, since
> a ServletContextListener is a Servlet API component, then the Servlet
> specification is supposed to resolve this one way or the other, but I don't
> think it does. In a similar case the language is "log and fail to deploy".
> As this is application related it could be reasonable to stop there.
>
> Rémy
>
>
> >
> > [1]
> >
> >
> https://github.com/apache/tomcat/blob/master/java/org/apache/catalina/core/StandardContext.java#L4669
> >
> > Romain Manni-Bucau
> > @rmannibucau <https://twitter.com/rmannibucau> | Blog
> > <https://rmannibucau.metawerx.net/> | Old Blog
> > <http://rmannibucau.wordpress.com> | Github <
> > https://github.com/rmannibucau> |
> > LinkedIn <https://www.linkedin.com/in/rmannibucau> | Book
> > <
> >
> https://www.packtpub.com/application-development/java-ee-8-high-performance
> > >
> >
>
Re: "Missing" break in listenerStart?
Posted by Rémy Maucherat <re...@apache.org>.
On Tue, Jan 12, 2021 at 5:49 PM Romain Manni-Bucau <rm...@gmail.com>
wrote:
> Hi all,
>
> I suspect it is intended but if so I wonder if it needs some toggle to
> disable that behavior: is the fact to not break when a listener (start)
> fails intended? ([1])
>
> An ASF friend hit that with 2 listeners and second one was failling after
> first one failed because it was depending on it.
>
> Since this is not uncommon I wonder if it should get a break once ok=false
> (issue can be listenerStop which should probably be independent of start
> chain behavior since some listener only impl it) or if we should have a
> flag in StandardContext to stop at first start failure.
>
> Anything already thought on it?
>
For all other subcomponents of the context, the behavior is: set ok to
false, log the error and continue. It should stay that way. However, since
a ServletContextListener is a Servlet API component, then the Servlet
specification is supposed to resolve this one way or the other, but I don't
think it does. In a similar case the language is "log and fail to deploy".
As this is application related it could be reasonable to stop there.
Rémy
>
> [1]
>
> https://github.com/apache/tomcat/blob/master/java/org/apache/catalina/core/StandardContext.java#L4669
>
> Romain Manni-Bucau
> @rmannibucau <https://twitter.com/rmannibucau> | Blog
> <https://rmannibucau.metawerx.net/> | Old Blog
> <http://rmannibucau.wordpress.com> | Github <
> https://github.com/rmannibucau> |
> LinkedIn <https://www.linkedin.com/in/rmannibucau> | Book
> <
> https://www.packtpub.com/application-development/java-ee-8-high-performance
> >
>