File to write the Java process ID to. If set, a file containing the
pid of the Java process will be written to the specified location
when the process is launched. The file will be deleted when the
Java process has terminated. Each time the Wrapper restarts the JVM,
the file will be updated with the current java pid. This property is
not set by default. Common values are
./myapp.java.pid or
/var/run/myapp.java.pid.
NOTE
If a second instance of the Wrapper is started, the pid file of the
first instance will be overwritten by the second instance. This is
done to avoid problems with stale pid files preventing the wrapper
and its jvm from starting.