[KARAF-2531] NPE in log:tail after a log:clear

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Duplicate
• Affects Version/s: 2.3.3
• Fix Version/s: 2.4.0, 3.0.0, 2.3.4
• Assignee: Jean-Baptiste Onofré
• Reporter: Jonathan Anstey
• Created: 25/Oct/13 19:29
• Updated: 02/Nov/13 17:39
• Resolved: 25/Oct/13 19:53

Description

Get this sometimes when doing a log:tail after a log:clear:

Exception in thread "pool-36-thread-1" java.lang.NullPointerException
	at org.apache.karaf.shell.log.layout.PatternParser$DatePatternConverter.convert(PatternParser.java:428)
	at org.apache.karaf.shell.log.layout.PatternConverter.format(PatternConverter.java:61)
	at org.apache.karaf.shell.log.DisplayLog.display(DisplayLog.java:153)
	at org.apache.karaf.shell.log.LogTail$PrintEventThread.run(LogTail.java:80)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
	at java.lang.Thread.run(Thread.java:724)

It requires a simple guard that we do elsewhere in the log commands:

diff --git a/shell/log/src/main/java/org/apache/karaf/shell/log/LogTail.java b/shell/log/src/main/java/org/apache/karaf/shell/log/LogTail.java
index 547c05d..4951984 100644
--- a/shell/log/src/main/java/org/apache/karaf/shell/log/LogTail.java
+++ b/shell/log/src/main/java/org/apache/karaf/shell/log/LogTail.java
@@ -77,7 +77,9 @@ public class LogTail extends DisplayLog {
 
             Iterable<PaxLoggingEvent> le = events.getElements(entries == 0 ? Integer.MAX_VALUE : entries);
             for (PaxLoggingEvent event : le) {
-                display(cnv, event, out);
+                if (event != null) {
+                    display(cnv, event, out);
+                }
             }
             // Tail
             final BlockingQueue<PaxLoggingEvent> queue = new LinkedBlockingQueue<PaxLoggingEvent>();

I'll push the commit once I get my karma set up.

Issue Links

• duplicates: KARAF-2515 Prevent NPE in log:tail