The accepted answer allowed me to get Eclipse started again, but it seems that the projects lost their metadata. (E.g., all the Git/Gradle/Spring icons disappeared from the project names.) I have a lot of projects in there, and I didn't want to have to import them all over again.
So here's what worked for me under Kepler. YMMV but I wanted to record this just in case it helps somebody.
Step 1. Temporarily move the .projects
file out of the way:
$ cd .metadata/.plugins/org.eclipse.core.resources
$ mv .projects .projects.bak
Step 2. Then start Eclipse. The metadata will be missing, but at least Eclipse starts without getting stuck.
Step 3. Close Eclipse.
Step 4. Revert the .projects.bak
file to its original name:
$ mv .projects.bak .projects
Step 5. Restart Eclipse. It may build some stuff, but this time it should get through. (At least it did for me.)