Bug in 2.3-HEAD: ConcurrentModificationException thrown by DynamicURI: ArrayList implementation not threadsafe

[Bart Selders <ba...@ibanx.nl>]

Hi,

In 2.3 HEAD I get a ConcurrentModificationException exception when 
removing parameter data from DynamicURI. Current DynamicURI (1.16) uses 
an ArrayList for pathInfo & queryString. Before version 1.11 a Vector 
was used. ArrayList is not threadsafe.

Stacktrace from my log file:

2003-03-29 21:08:43,864 ERROR org.apache.turbine.util.DynamicURI - Could 
not remove showAs
java.util.ConcurrentModificationException
	at 
java.util.AbstractList$Itr.checkForComodification(AbstractList.java:444)
	at java.util.AbstractList$Itr.next(AbstractList.java:421)
	at org.apache.turbine.util.DynamicURI.remove(DynamicURI.java:668)
	at org.apache.turbine.util.DynamicURI.removePathInfo(DynamicURI.java:725)
	at ibanx.turbine.tools.LinkTool.setPathInfo(LinkTool.java:259)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at 
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
	at 
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
	at java.lang.reflect.Method.invoke(Method.java:324)


Snippet from ArrayList Javadoc:
<snip>
Note that this implementation is not synchronized. If multiple threads 
access an ArrayList instance concurrently, and at least one of the 
threads modifies the list structurally, it must be synchronized 
externally. (A structural modification is any operation that adds or 
deletes one or more elements, or explicitly resizes the backing array; 
merely setting the value of an element is not a structural modification.)
</snip>

One way to reproduce this behaviour is by using the following snippet in 
a velocity template:

    $link.addPathInfo("test","x").removePathInfo("test")

An exception is thrown in the logfile.

Bart



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