[Fix #390] Implement a workaround for orphaned Java process on Windows (#2051)

After quitting the REPL child Java processes on Windows weren't properly killed (likely an Emacs bug). Seems that `interrupt-process` does the trick, so now we use `interrupt-process` instead of `kill-process` if the OS is Windows.

Author: benedekfazekas

CHANGELOG.md

@@ -60,6 +60,7 @@
 * [#1895](https://github.com/clojure-emacs/cider/issues/1895): Connect to the same host:port after `cider-restart` if the connection was established with `cider-connect`.
 * [#1881](https://github.com/clojure-emacs/cider/issues/1881): Add `cider-cljs-boot-repl` and `cider-cljs-gradle-repl` defcustom and hook `boot-cljs-repl`.
 * [#1997](https://github.com/clojure-emacs/cider/pull/1997): Fix a nil error when loading a code buffer and the error buffer is visible.
+* [#390](https://github.com/clojure-emacs/cider/issues/390): Workaround for orphaned java process on windows machine after quitting the REPL.
 
 ## 0.14.0 (2016-10-13)
 

nrepl-client.el

@@ -616,6 +616,13 @@ If NO-ERROR is non-nil, show messages instead of throwing an error."
 
 
 ;;; Client: Process Handling
+(defun nrepl--kill-process (proc)
+  "Kill PROC using the appropriate, os specific way.
+Implement a workaround to clean up an orphaned JVM process left around
+after exiting the REPL on some windows machines."
+  (if (memq system-type '(cygwin windows-nt))
+      (interrupt-process proc)
+    (kill-process proc)))
 
 (defun nrepl--maybe-kill-server-buffer (server-buf)
   "Kill SERVER-BUF and its process, subject to user confirmation.
@@ -628,7 +635,7 @@ Do nothing if there is a REPL connected to that server."
       (let ((proc (get-buffer-process server-buf)))
         (when (process-live-p proc)
           (set-process-query-on-exit-flag proc nil)
-          (kill-process proc))
+          (nrepl--kill-process proc))
         (kill-buffer server-buf)))))
 
 ;; `nrepl-start-client-process' is called from `nrepl-server-filter'. It