Some Eclipse Foundation services are deprecated, or will be soon. Please ensure you've read this important communication.

Bug 512334

Summary: MarkerComparator violates its general contract
Product: [Eclipse Project] Platform Reporter: Sergey Prigogin <eclipse.sprigogin>
Component: UIAssignee: Platform-UI-Inbox <Platform-UI-Inbox>
Status: CLOSED DUPLICATE QA Contact:
Severity: normal    
Priority: P3 CC: javadev, loskutov
Version: 3.8.2   
Target Milestone: ---   
Hardware: All   
OS: All   
Whiteboard:

Description Sergey Prigogin CLA 2017-02-16 17:53:30 EST 
4.7.0.I20170208-2000:

!MESSAGE An internal error occurred during: "Searching for markers".
!STACK 0
java.lang.IllegalArgumentException: Comparison method violates its general contract!
	at java.util.TimSort.mergeHi(TimSort.java:899)
	at java.util.TimSort.mergeAt(TimSort.java:516)
	at java.util.TimSort.mergeCollapse(TimSort.java:441)
	at java.util.TimSort.sort(TimSort.java:245)
	at java.util.Arrays.sort(Arrays.java:1512)
	at org.eclipse.ui.internal.views.markers.MarkerSortUtil.sortStartingKElement(MarkerSortUtil.java:326)
	at org.eclipse.ui.internal.views.markers.Markers.sortMarkerEntries(Markers.java:160)
	at org.eclipse.ui.internal.views.markers.Markers.sortAndMakeCategories(Markers.java:133)
	at org.eclipse.ui.internal.views.markers.Markers.updateWithNewMarkers(Markers.java:97)
	at org.eclipse.ui.internal.views.markers.MarkerUpdateJob.processMarkerEntries(MarkerUpdateJob.java:125)
	at org.eclipse.ui.internal.views.markers.MarkerUpdateJob.buildMarkers(MarkerUpdateJob.java:79)
	at org.eclipse.ui.internal.views.markers.MarkerUpdateJob.run(MarkerUpdateJob.java:51)
	at org.eclipse.core.internal.jobs.Worker.run(Worker.java:56)
Comment 1 Andrey Loskutov CLA 2017-02-19 08:18:39 EST 
The root cause is that MarkerComparator violates its general contract: the repeated invocation of compare() with same arguments can return different results, because the MarkerComparator depends on mutable internal AND external state during comparison.

While performing Problems view update, MarkerUpdateJob (running in background thread) will fail if the MarkerComparator compare algorithm changes, because MarkerUpdateJob sorts the Problems view entries using MarkerComparator.

MarkerComparator.compare() uses compareCategory() and compareFields().

compareCategory() is unstable and depends on external state because it uses org.eclipse.ui.views.markers.MarkerField.compare(MarkerItem, MarkerItem) method, which (in at least one implementation I found) uses mutable markers model to compute results. E.g. if marker was deleted during sort, but MarkerItem still contains the reference to it, TypeMarkerField.getValue() will return marker type id at the begin of the sort and "Other" after deletion of the marker.

compareFields() is unstable and depends on internal state because both "descendingFields" and "fields" fields which are used in compareFields() are mutable via setPrimarySortField().

To reproduce the later case (have not tried yet, but this is the most likely from looking at code): constantly change some resource with some background job and at same time constantly click on different column headers in the Problems view.
Comment 2 Andrey Loskutov CLA 2017-10-19 05:33:09 EDT 
*** Bug 468234 has been marked as a duplicate of this bug. ***
Comment 3 Andrey Loskutov CLA 2017-10-19 05:35:12 EDT 

*** This bug has been marked as a duplicate of bug 371586 ***