Putting this out there in case somebody has the same problem. I upgraded my Jenkins box to OS X Mavericks, and Jenkins stopped responding; requests to localhost:8080 simply dropped.
After a bit of digging and dead ends, I found out that java wasn’t installed. Running
from the command line failed, and asked me to install Java. I installed the lastest JDK, restarted jenkins with these commands:
sudo launchctl unload -w /Library/LaunchDaemons/org.jenkins-ci.plist sudo launchctl load -w /Library/LaunchDaemons/org.jenkins-ci.plist
and everything seems to be back to normal.