Eclipse Suddenly Takes Long to Start Unit Tests

10. May, 2012

When starting a JUnit test in Eclipse suddenly takes ages (the process starts quickly as you can see in the Console view but it takes ages until the tree of tests appears in the JUnit view), you might experience troubles with IPv6.

The background of the issue: Modern OSs assign your network cards two addresses, one for the old IPv4 and one for the new IPv6. When IPv6 isn’t configured correctly, Eclipse will try to connect via this route and it will take some 30 seconds for Eclipse and the JUnitRunner process to begin talking to each other.

The quick fix is to disable IPv6 or to tell Java to prefer IPv4:

How To Disable IPv6 In Ubuntu

30. April, 2012

If you’re getting errors from squid or your web browser with some weird IP address, chances are that squid is trying to connect to a server which supports IPv4 and IPv6.

To disable IPv6 on Ubuntu (also Kubuntu), add this line to the end of /etc/sysctl.conf:

net.ipv6.conf.all.disable_ipv6 = 1

Restart your computer or reload sysctl.conf by executing: sudo sysctl -p

To check, run: ip a | grep inet6

When IPv6 is disabled, this will give no output.

Source: Quick Tip: How To Disable IPv6 In Ubuntu For Better Internet Speed

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