Add regression tests for inheritable thread-local memory leak

Leak was introduced in commit 3c80a36527, fixing #128, but introducing
#288 instead, which was the lesser of two evils, but still bad for some
users unwilling to use native AspectJ syntax for their aspects, avoiding
the problem.

Relates to #288.

Signed-off-by: Alexander Kriegisch <Alexander@Kriegisch.name>

1 files changed, 104 insertions, 0 deletions

diff --git a/tests/bugs1921/github_288/NestedAroundClosureMemoryLeakTest.java b/tests/bugs1921/github_288/NestedAroundClosureMemoryLeakTest.java
new file mode 100644
index 000000000..54a5eb1cc
--- /dev/null
+++ b/tests/bugs1921/github_288/NestedAroundClosureMemoryLeakTest.java
@@ -0,0 +1,104 @@
+import java.lang.reflect.Field;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Set;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+
+public class NestedAroundClosureMemoryLeakTest {
+
+  public static void main(String[] args) throws Exception {
+    if (args.length > 0 && "oom".equals(args[0]))
+      testNoMemoryLeak_SystemShouldNotRunOutOfMemory();
+    else
+      testNoMemoryLeak_InheritableThreadLocalCleared();
+  }
+
+  /**
+   * Tests that the inheritable thread-locals of the spawned threads are either null or contain all null elements
+   */
+  public static void testNoMemoryLeak_InheritableThreadLocalCleared() throws Exception {
+    int numThreadPools = 1;
+    List<ExecutorService> executorServices = createExecutorServicesWithFixedThreadPools(numThreadPools);
+    try {
+      executeTasksAndGC(executorServices);
+
+      Field mapField = Thread.class.getDeclaredField("inheritableThreadLocals");
+      mapField.setAccessible(true);
+      Set<Thread> threads = Thread.getAllStackTraces().keySet();
+
+      threads.stream()
+        .filter(thread -> thread.getName().contains("pool"))
+        .forEach(thread -> {
+          try {
+            Object inheritableThreadLocals = mapField.get(thread);
+            if (inheritableThreadLocals != null) {
+              Field tableField = inheritableThreadLocals.getClass().getDeclaredField("table");
+              tableField.setAccessible(true);
+              Object[] inheritableThreadLocalTable = (Object[]) tableField.get(inheritableThreadLocals);
+              if (inheritableThreadLocalTable != null) {
+                for (Object entry : inheritableThreadLocalTable)
+                  assert entry == null : "All inheritable thread-locals should be null after GC";
+              }
+            }
+          }
+          catch (Exception e) {
+            throw new RuntimeException(e);
+          }
+        });
+
+      System.out.println("Test passed - all inheritable thread-locals are null after GC");
+    }
+    finally {
+      for (ExecutorService executorService : executorServices)
+        executorService.shutdown();
+    }
+  }
+
+  /**
+   * Executes tasks in multiple threads, using one executor service with a fixed thread pool of size 1 per task. This
+   * ensures that each spawned thread gets initialised for the first time and allocates memory for inheritable
+   * thread-locals, exposing possible memory leaks when running @AspectJ aspects with non-inlined, nested around advices
+   * in multi-thread situations.
+   * <p>
+   * If each thread allocates memory for a stack of around closures (memory leak case) according to
+   * <a href="https://github.com/eclipse-aspectj/aspectj/issues/288">GitHub issue 288</a>, the program will run out of
+   * memory. When fixed, this should no longer happen.
+   * <p>
+   * Run this test e.g. with {@code -Xmx1G} for 10 x 128 MB memory consumption to ensure an out of memory error in the
+   * leak case. Any other appropriate combination of number of threads and memory limit is also OK.
+   */
+  public static void testNoMemoryLeak_SystemShouldNotRunOutOfMemory() throws Exception {
+    int numThreadPools = 5;
+    List<ExecutorService> executorServices = createExecutorServicesWithFixedThreadPools(numThreadPools);
+    try {
+      executeTasksAndGC(executorServices);
+      System.out.println("Test passed - no OutOfMemoryError due to inheritable thread-locals memory leak");
+    }
+    finally {
+      for (ExecutorService executorService : executorServices)
+        executorService.shutdown();
+    }
+  }
+
+  private static List<ExecutorService> createExecutorServicesWithFixedThreadPools(int count) {
+    List<ExecutorService> executorServiceList = new ArrayList<>(count);
+    for (int i = 0; i < count; i++)
+      executorServiceList.add(Executors.newFixedThreadPool(1));
+    return executorServiceList;
+  }
+
+  private static void executeTasksAndGC(List<ExecutorService> executorServices) throws Exception {
+    for (ExecutorService executorService : executorServices)
+      new MemoryHog(executorService).doSomething();
+    System.out.println("Finished executing tasks");
+
+    // Best effort GC
+    System.gc();
+    System.out.println("Finished executing GC");
+
+    // Sleep to take a memory dump
+    // Thread.sleep(500000);
+  }
+
+}