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2026-11-06 21:43:48 +05:30
parent ecceaa8b32
commit f7b6c1efca
33 changed files with 1258 additions and 0 deletions
@@ -0,0 +1,29 @@
+import sun.misc.Unsafe;
+
+/**
+ * Smallest possible Unsafe memory access: allocate 8 bytes off-heap, write a long, read it back, free it.
+ * Run it under each value of --sun-misc-unsafe-memory-access to see what the JVM does.
+ */
+public class Probe {
+    public static void main(String[] args) {
+        Unsafe u = UnsafeAccess.get();
+        System.out.println("got Unsafe instance");
+        try {
+            long addr = u.allocateMemory(8);
+            u.putLong(addr, 42L);
+            System.out.println("read back " + u.getLong(addr));
+            u.freeMemory(addr);
+            System.out.println("allocate/put/get/free all succeeded");
+        } catch (Throwable t) {
+            System.out.println("FAILED: " + t);
+        }
+        try {
+            long addr2 = u.allocateMemory(8);
+            u.putLong(addr2, 7L);
+            System.out.println("second use read " + u.getLong(addr2));
+            u.freeMemory(addr2);
+        } catch (Throwable t) {
+            System.out.println("second use FAILED: " + t);
+        }
+    }
+}