Put other shutdown thread in own thread group (#376)

classgraph · Oct 19, 2019 · e22b375 · e22b375
1 parent fceb181
commit e22b375
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Showing 2 changed files with 16 additions and 7 deletions.
diff --git a/src/main/java/io/github/classgraph/ScanResult.java b/src/main/java/io/github/classgraph/ScanResult.java
@@ -237,8 +237,16 @@ public void run() {
             }
         }
 
+        ThreadGroup parentThreadGroup = Thread.currentThread().getThreadGroup();
+        for (; parentThreadGroup.getParent() != null; parentThreadGroup = parentThreadGroup.getParent()) {
+            // Find system (toplevel) thread group, and use this as the parent thread group, in order to
+            // drop any references to the container's context classloader, so that it may be garbage collected
+            // if the application is unloaded (#376).
+        }
+        parentThreadGroup = new ThreadGroup(parentThreadGroup, "ClassGraph-shutdown-thread-group");
+
         // Create shutdown hook thread to close all open/mapped DirectByteBuffers on shutdown
-        final Thread hookThread = new Thread() {
+        final Thread hookThread = new Thread(parentThreadGroup, new Runnable() {
             @Override
             public void run() {
                 // Close all ScanResult instances that have not yet been closed
@@ -253,7 +261,7 @@ public void run() {
                     }
                 }
             }
-        };
+        }, "ClassGraph-shutdown-thread");
         // Set shutdown hook thread classloader to system classloader, dropping ref to context classloader
         hookThread.setContextClassLoader(systemClassLoader);
 

diff --git a/src/main/java/nonapi/io/github/classgraph/concurrency/SimpleThreadFactory.java b/src/main/java/nonapi/io/github/classgraph/concurrency/SimpleThreadFactory.java
@@ -92,13 +92,14 @@ public Thread newThread(final Runnable runnable) {
                 // as the parent thread group, in order to drop any references to the container's context
                 // classloader, so that it may be garbage collected if the application is unloaded (#376).
             }
-            parentThreadGroup = new ThreadGroup(parentThreadGroup, threadNamePrefix + "threadgroup");
+            parentThreadGroup = new ThreadGroup(parentThreadGroup, threadNamePrefix + "thread-group");
         }
-        final Thread t = new Thread(parentThreadGroup, runnable, threadNamePrefix + threadIdx.getAndIncrement());
+        final Thread thread = new Thread(parentThreadGroup, runnable,
+                threadNamePrefix + threadIdx.getAndIncrement());
         if (threadContextClassLoader != null) {
-            t.setContextClassLoader(threadContextClassLoader);
+            thread.setContextClassLoader(threadContextClassLoader);
         }
-        t.setDaemon(daemon);
-        return t;
+        thread.setDaemon(daemon);
+        return thread;
     }
 }