#1632 ConcurrentModificationException in DomElement.printOpeningTagContentAsXml

[Philip Potter]

I just got a ConcurrentModificationException from calling into htmlunit code. Here is the (truncated) stacktrace:

java.util.ConcurrentModificationException at java.util.LinkedHashMap$LinkedHashIterator.nextEntry(LinkedHashMap.java:394) at java.util.LinkedHashMap$EntryIterator.next(LinkedHashMap.java:413) at java.util.LinkedHashMap$EntryIterator.next(LinkedHashMap.java:412) at com.gargoylesoftware.htmlunit.html.DomElement.printOpeningTagContentAsXml(DomElement.java:144) at com.gargoylesoftware.htmlunit.html.HtmlElement.toString(HtmlElement.java:614) at java.lang.String.valueOf(String.java:2847) at java.lang.StringBuilder.append(StringBuilder.java:128) at com.gargoylesoftware.htmlunit.javascript.host.html.HTMLElement.toString(HTMLElement.java:1749) at java.lang.String.valueOf(String.java:2847) at java.lang.StringBuilder.append(StringBuilder.java:128) at com.gargoylesoftware.htmlunit.javascript.host.Event.toString(Event.java:686) at java.lang.String.valueOf(String.java:2847) at java.lang.StringBuilder.append(StringBuilder.java:128) at com.gargoylesoftware.htmlunit.html.HtmlElement.fireEvent(HtmlElement.java:864) at com.gargoylesoftware.htmlunit.html.HtmlElement.type(HtmlElement.java:482) at com.gargoylesoftware.htmlunit.html.HtmlElement.type(HtmlElement.java:431) at com.gargoylesoftware.htmlunit.html.HtmlElement.type(HtmlElement.java:400) at org.openqa.selenium.htmlunit.HtmlUnitKeyboard.sendKeys(HtmlUnitKeyboard.java:70) at org.openqa.selenium.htmlunit.HtmlUnitWebElement.sendKeys(HtmlUnitWebElement.java:343)

HtmlUnitWebElement.sendkeys is where my user code called into htmlunit. Running the same test again did not reproduce the error. The gradle dependencies we are using are: 'org.seleniumhq.selenium:selenium-java:2.33.0', 'org.seleniumhq.selenium:selenium-htmlunit-driver:2.33.0'.

I wonder if this is also the cause of jwebunit bug 114.

[RBRi]

Hi Philip,

usually this happens, if there is some javascript that modifies the dom tree in parallel to you foreground task.
Did a quick look at the code and this special case seems to be triggered by some debug code (HTMLElement.toString). So for your case changing the log level to info/warn for HTMLElement might help.

Will think about this, maybe we can change at least the toString code in a way, that it will not influence the normal program flow.

[RBRi]

There is a 'fix' in SVN. At least the toString method now ignores the CME.

Thanks for reporting

[RBRi]

Sorry but i had to revert the fix because it was only a hack.