Debugging Windows file locking

Root cause and fix

The main source of all Windows locking problems are unclosed AutoCloseable subclasses.

This includes, but is not limited to, incorrect usage of:

• Files.newInputStream
• Files.list(...)

Ensure that these use the .use { } scope function or our Path.list(block: (Stream<Path>) -> R) extension function.

Debugging with Linux

To find any files opened by Linux, where the file descriptor was not released, run this command:

ls -l /proc/<pid>/fd

If you are debugging an integration test, to retrieve the file descriptors:

1. Find the pid while grepping for the port:

   ps -cdef | grep 'address=5005'
   

2. Generalise that to a watch task:

   watch -n 1 ls -l /proc/$(ps -cdef | grep 'address=5005' | head -1 | awk '{print$2}')/fd \| grep junit
   

3. grep it for files in junit folders.

   You can now run the integration (or unit tests if you omit 5005) and step through watching when file descriptors appear.