Eclipse: Debugging & inspection of variables causes com.sun.jdi.ObjectCollectedException

Question

I debug my program and add here and there a breakpoint. After a stop I want to inspect some of the variables and get sometimes a com.sun.jdi.ObjectCollectedException. After searching in different sources I figured out that most likely the object was Garbage Collected. Clicking here and there I could retrieve my object by nevertheless in the Variables view I cannot inspect the variable.

-vmargs
-Dosgi.requiredJavaVersion=1.8
[email protected]/eclipse-workspace
-XX:+UseG1GC
-XX:+UseStringDeduplication
--add-modules=ALL-SYSTEM
-Dosgi.requiredJavaVersion=1.8
-Xms512m
-Xmx4096m
--add-modules=ALL-SYSTEM

I'm running under Linux/OpenSuSe with OpenJDK 1.8.0_151. Any hints how to avoid that kind of GC problems? Is this some kind of setting in the IDE?

Solution 1

Right click the variable, then click "Show Logical Structure", uncheck any collection.

Solution 2

While execution of your code is stopped at a breakpoint:

1. Right-click the variable in the Variables pane
2. Clicking on the collections (such as the Array in the image below) will uncheck them
3. Now you can inspect the variable

Solution 3

This bug has been fixed in Eclipse 4.18

https://www.eclipse.org/eclipse/news/4.18/jdt.php

Stabilized logical structures in Variables view with active GC

The Debug view no longer breaks when logical structures are shown while the application's garbage collector is active (com.sun.jdi.ObjectCollectedException occurred while retrieving value).

Comments

[LMC]

If the object was garbage collected you are inspecting it at the wrong place, the object is alive before that breakpoint.

[LeO]

Yeah, but after a while keeping the editor open the object cannot be inspected any further. Therefore I assume its GCed

[Jeremy Bunn]

Try this fix: stackoverflow.com/a/49003027/2733353

[M46]

Works for me but I don't understand why?

[javaPlease42]

Note: The variable that you right click must be a collection and not an Object.