John,
On 2/17/22 10:46, John Barrow wrote:
Hi,
I am now running Tomcat version 10.0.16 having just upgraded from
9.0.41. As a developer, I make use of the META-INF\context.xml feature
to detect changes within the classes folder WEB-INF\classes by
<Context reloadable="true"></Context>
However, since moving to Tomcat 10.0.16, the reload keeps crashing
Tomcat due to the fact that Netbeans is recompiling multiple files and
as soon as the first file is completed, I believe that Tomcat triggers
its reload process and then fails as one of the listener classes is
still in the process of being rebuilt by Netbeans and so Tomcat can’t
access it for that split second to install the listener.
If I shut down Tomcat and re-open it again, all is well as Netbeans
has then had time to finish the re-compile.
If I make a change within the implementation of (say) one of the
listeners, so that Netbeans only has to re-compile that one .class
file, then Tomcat reloads the application perfectly.
Therefore, I was looking for the ability to add a delay to force
Tomcat, on having detected a change in one of the files, to wait a
moment to let Netbeans finish its job. I have researched the relevant
help files and read through
https://tomcat.apache.org/tomcat-8.0-doc/config/context.html and can’t
see any additional attribute that might handle this scenario.
If there isn’t an option, is it valid to raise it in the Bug Database?
I have searched the existing list and can’t see any previous mention
of it.
For some reason, I didn’t experience this while using Tomcat 9.0.41,
but it may have been slower to react to the .class files being change
and so did not have an issue with the files not being available while
they were being recompiled.
The relevant part of the log is as below
17-Feb-2022 14:47:54.861 SEVERE [Catalina-utility-2]
org.apache.catalina.core.StandardContext.listenerStart Error
configuring application listener of class [Listener.DataDictionary]
java.lang.ClassNotFoundException: Listener.DataDictionary
at
org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1444)
at
org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1252)
at
org.apache.catalina.core.DefaultInstanceManager.loadClass(DefaultInstanceManager.java:535)
at
org.apache.catalina.core.DefaultInstanceManager.loadClassMaybePrivileged(DefaultInstanceManager.java:516)
at
org.apache.catalina.core.DefaultInstanceManager.newInstance(DefaultInstanceManager.java:150)
at
org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4640)
at
org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5179)
at
org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
at
org.apache.catalina.core.StandardContext.reload(StandardContext.java:3781)
at
org.apache.catalina.loader.WebappLoader.backgroundProcess(WebappLoader.java:268)
at
org.apache.catalina.core.StandardContext.backgroundProcess(StandardContext.java:5562)
at
org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.processChildren(ContainerBase.java:1365)
at
org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.processChildren(ContainerBase.java:1369)
at
org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.processChildren(ContainerBase.java:1369)
at
org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.run(ContainerBase.java:1347)
at
java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:539)
at
java.base/java.util.concurrent.FutureTask.runAndReset(FutureTask.java:305)
at
java.base/java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:305)
at
java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136)
at
java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)
at
org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at
java.base/java.lang.Thread.run(Thread.java:833)
17-Feb-2022 14:47:54.861 SEVERE [Catalina-utility-2]
org.apache.catalina.core.StandardContext.listenerStart Skipped
installing application listeners due to previous error(s)
Thanks in advance and here’s hoping to not have to have to keep
Stopping & Starting Tomcat for every development change.
This kind of thing could happen due to a number of different reasons,
such as a slow disk or network share, etc. and ought to be
protected-against.
I haven't looked at the code, but I would imagine it periodically reads
all relevant files looking for anything that's been updated, but
immediately acts the first time is finds someting worth triggering a reload.
It might make more sense to modify that logic so that *all* files are
checked, but we cancel the reload if there are any files that are "too
new". This would allow us to avoid a reload if some kind of copy is in
progress. So we are looking for "anything newer than
last_reload_timestamp but not if we find anything older than NOW - 10
seconds".
Would you be interested in looking at the existing algorithm to see if
it would be updated in this way?
-chris
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