diff --git a/Client-server-discovery-lifecycle.md b/Client-server-discovery-lifecycle.md
index 9f11c8e..8f95a95 100644
--- a/Client-server-discovery-lifecycle.md
+++ b/Client-server-discovery-lifecycle.md
@@ -47,3 +47,28 @@ This proposal is intended to "self-heal" and work in practice without asking use
 ## Proposal 2: Some other idea here
 
 * is there some way we can get an actual, reliable lock on a project directory, cross-platform?
+
+The sbt launcher provides a locking facility.
+
+ * currently used in practice to:
+  + lock down the Ivy cache
+  + lock parts of the sbt boot directory
+ * locks access jvm-wide on a file
+  + combination synchronized + file lock
+  + only allows one thread across all (cooperating) Java processes
+ * deals with some weird implementation details
+  + overlapping file lock exceptions from Java when locking in the same JVM
+  + workaround OS deadlock detection, which is often spurious in a multi-threaded application
+ * won't magically work on NFS or other environments with poor/missing lock support
+ * OS will clean up the lock if the process locking it dies
+ * blocking only- no tryLock to only attempt a lock and return quickly if not available
+ * API for [File.createNewFile](http://docs.oracle.com/javase/6/docs/api/java/io/File.html#createNewFile%28%29) says it shouldn't be used for file locking (don't know why)
+ * could use for server startup roughly like:
+```scala
+   val f = <project-lock-file>
+   withLock(f) {
+     val port = read(f)
+     tryConnect(port)
+       fail: port = start new process; write(f, port)
+   }
+```