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Posted to commits@wicket.apache.org by "Ryo Tsunoda (Jira)" <ji...@apache.org> on 2022/04/11 09:14:00 UTC
[jira] [Created] (WICKET-6971) NullPointerException in ModificationWatcher
Ryo Tsunoda created WICKET-6971:
-----------------------------------
Summary: NullPointerException in ModificationWatcher
Key: WICKET-6971
URL: https://issues.apache.org/jira/browse/WICKET-6971
Project: Wicket
Issue Type: Bug
Environment: * Eclipse Version: 2021-12 (4.22.0) Build id: 20211202-1639
* Tomcat 9.0.44
* Java11(amazon-corretto-11.0.10.9.1-windows-x64-jdk)
Reporter: Ryo Tsunoda
Sometimes this exception occurs after I edit the CSS.
```
2022-04-09 19:28:48.252 | ERROR | [ModificationWatcher Task] | org.apache.wicket.util.thread.Task | Unhandled exception thrown by user code in task ModificationWatcher
java.lang.NullPointerException: null
at org.apache.wicket.util.io.Connections.close(Connections.java:133) ~[wicket-util-8.14.0.jar:8.14.0]
at org.apache.wicket.core.util.resource.UrlResourceStream.updateContentLength(UrlResourceStream.java:247) ~[wicket-core-8.14.0.jar:8.14.0]
at org.apache.wicket.core.util.resource.UrlResourceStream.lastModifiedTime(UrlResourceStream.java:224) ~[wicket-core-8.14.0.jar:8.14.0]
at org.apache.wicket.markup.MarkupResourceStream.lastModifiedTime(MarkupResourceStream.java:148) ~[wicket-core-8.14.0.jar:8.14.0]
at org.apache.wicket.util.watch.ModificationWatcher.checkModified(ModificationWatcher.java:157) ~[wicket-util-8.14.0.jar:8.14.0]
at org.apache.wicket.util.watch.ModificationWatcher$1.run(ModificationWatcher.java:143) ~[wicket-util-8.14.0.jar:8.14.0]
at org.apache.wicket.util.thread.Task$1.run(Task.java:116) [wicket-util-8.14.0.jar:8.14.0]
at java.lang.Thread.run(Thread.java:829) [?:?]
```
connection.getInputStream() returns null.
Wicket can check null here.
[https://github.com/apache/wicket/blob/wicket-8.x/wicket-util/src/main/java/org/apache/wicket/util/io/Connections.java#L133]
Tomcat's CachedResourceURLConnection#getInputStream() sometimes returns a WebResource instance with no stream.
[https://github.com/apache/tomcat/blob/9.0.x/java/org/apache/catalina/webresources/CachedResource.java#L516]
I don't know the conditions under which it can be reproduced.
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