--- a/langtools/src/jdk.compiler/share/classes/com/sun/tools/javac/file/JavacFileManager.java	Wed Jul 05 20:06:12 2017 +0200
+++ b/langtools/src/jdk.compiler/share/classes/com/sun/tools/javac/file/JavacFileManager.java	Thu Oct 30 16:08:43 2014 -0700
@@ -132,6 +132,8 @@
         setContext(context);
         if (System.getProperty("show.fm.open.close") != null)
             System.err.println("JavacFileManager.open " + this.hashCode());
+        if (System.getProperty("trace.fm.open.close") != null)
+            Thread.dumpStack();
     }
 
     /**
@@ -575,6 +577,8 @@
     public void close() {
         if (System.getProperty("show.fm.open.close") != null)
             System.err.println("JavacFileManager.close " + this.hashCode());
+        if (System.getProperty("trace.fm.open.close") != null)
+            Thread.dumpStack();
         for (Iterator<Archive> i = archives.values().iterator(); i.hasNext(); ) {
             Archive a = i.next();
             i.remove();