From 4df4d0eae33fbcffb0443fd5577ad2e4144da2bd Mon Sep 17 00:00:00 2001
From: Martin Quinson <martin.quinson@loria.fr>
Date: Sun, 26 Apr 2015 01:39:37 +0200
Subject: [PATCH] Actually allows the GC to reclaim tasks (fix #18874)

---
 ChangeLog                                   |  2 ++
 src/bindings/java/jmsg_task.c               | 10 ++++++++++
 src/bindings/java/jmsg_task.h               |  2 ++
 src/bindings/java/org/simgrid/msg/Task.java | 22 +++++++++++----------
 4 files changed, 26 insertions(+), 10 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index dc3e85d4e0..af38a7ee48 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -16,6 +16,8 @@ SimGrid (3.12) NOT RELEASED; urgency=low
    - Rename Process.currentProcess() to Process.getCurrentProcess()
    - Rename Task.setDataSize() to Task.setBytesAmount()
    - Merge Task.getRemainingDuration() and Task.getComputeDuration() into Task.getFlopsAmount()
+ * Bug fixes:
+   - #18874: Actually allows the GC to reclaim tasks
    
  SIMIX:
  * New functions
diff --git a/src/bindings/java/jmsg_task.c b/src/bindings/java/jmsg_task.c
index 850a999a2c..40cffed7a5 100644
--- a/src/bindings/java/jmsg_task.c
+++ b/src/bindings/java/jmsg_task.c
@@ -651,7 +651,17 @@ MSG_task_set_data(task, (void *) (*env)->NewGlobalRef(env, jtask));
   return jcomm;
 }
 
+JNIEXPORT void JNICALL
+Java_org_simgrid_msg_Task_doFinalize(JNIEnv * env, jobject jtask) {
+	  msg_task_t task = jtask_to_native_task(jtask, env);
+
+	  if (!task) {
+	    jxbt_throw_notbound(env, "task", jtask);
+	    return;
+	  }
 
+	  MSG_task_destroy(task);
+}
 
 static void msg_task_cancel_on_failed_dsend(void*t) {
   msg_task_t task = t;
diff --git a/src/bindings/java/jmsg_task.h b/src/bindings/java/jmsg_task.h
index 77daa9fbd0..2edb2caea1 100644
--- a/src/bindings/java/jmsg_task.h
+++ b/src/bindings/java/jmsg_task.h
@@ -71,6 +71,8 @@ Java_org_simgrid_msg_Task_nativeInit(JNIEnv *env, jclass cls);
 JNIEXPORT void JNICALL
 Java_org_simgrid_msg_Task_create
 		(JNIEnv * env, jobject jtask, jstring jname, jdouble jcomputeDuration, jdouble jmessageSize);
+JNIEXPORT void JNICALL
+Java_org_simgrid_msg_Task_doFinalize(JNIEnv * env, jobject jtask);
 /*
  * Class		org_simgrid_msg_Task
  * Method		parallelCreate
diff --git a/src/bindings/java/org/simgrid/msg/Task.java b/src/bindings/java/org/simgrid/msg/Task.java
index 95893ec91a..16e54ef1ac 100644
--- a/src/bindings/java/org/simgrid/msg/Task.java
+++ b/src/bindings/java/org/simgrid/msg/Task.java
@@ -161,17 +161,19 @@ public class Task {
 	/** Cancels a task. */ 
 	public native void cancel();
 
-	/** Deletes a task.
-	 *
-	 * @exception			NativeException if the destruction failed.
-	 */ 
-	protected void finalize() throws NativeException {
-		destroy();
+	/** Deletes a task once the garbage collector reclaims it */
+	@Override
+	protected void finalize() {
+		try {
+			// Exceptions in finalizers lead to bad situations:
+			// http://stackoverflow.com/questions/7644556/troubleshooting-a-java-memory-leak-finalization
+			doFinalize();
+			bind=0; // to avoid segfaults if the impossible happens yet again making this task surviving its finalize()
+		} catch (Exception e) {
+			e.printStackTrace();
+		}
 	}
-	/**
-	 * The natively implemented method to destroy a MSG task.
-	 */
-	protected native void destroy();
+	protected native void doFinalize();
 	/* *                       * *
 	 * * Communication-related * *
 	 * *                       * */
-- 
2.20.1