--- a/test/hotspot/jtreg/runtime/Dictionary/CleanProtectionDomain.java	Tue Sep 11 10:12:50 2018 -0700
+++ b/test/hotspot/jtreg/runtime/Dictionary/CleanProtectionDomain.java	Tue Sep 11 13:34:13 2018 -0400
@@ -45,6 +45,7 @@
     ProcessBuilder pb = ProcessTools.createJavaProcessBuilder(
                                   "-Xlog:protectiondomain+table=debug",
                                   "--add-exports=java.base/jdk.internal.misc=ALL-UNNAMED",
+                                  "-XX:+UnlockDiagnosticVMOptions",
                                   "-XX:+WhiteBoxAPI",
                                   "-Xbootclasspath/a:.",
                                   Test.class.getName());
@@ -70,13 +71,20 @@
 
       test();
 
-      System.gc();
       // Wait until ServiceThread cleans ProtectionDomain table.
       // When the TestClassLoader is unloaded by GC, at least one
       // ProtectionDomainCacheEntry will be eligible for removal.
-      do {
-        removedCount = wb.protectionDomainRemovedCount();
-      } while (removedCountOrig == removedCount);
+      int cnt = 0;
+      while (true) {
+        if (cnt++ % 30 == 0) {
+          System.gc();
+        }
+        removedCount = wb.resolvedMethodRemovedCount();
+        if (removedCountOrig != removedCount) {
+          break;
+        }
+        Thread.sleep(100);
+      }
     }
 
     private static class TestClassLoader extends ClassLoader {

--- a/test/hotspot/jtreg/runtime/MemberName/MemberNameLeak.java	Tue Sep 11 10:12:50 2018 -0700
+++ b/test/hotspot/jtreg/runtime/MemberName/MemberNameLeak.java	Tue Sep 11 13:34:13 2018 -0400
@@ -56,19 +56,26 @@
           mh.invokeExact(leak);
         }
 
-        System.gc();  // make mh unused
-
         // Wait until ServiceThread cleans ResolvedMethod table
-        do {
+        int cnt = 0;
+        while (true) {
+          if (cnt++ % 30 == 0) {
+            System.gc();  // make mh unused
+          }
           removedCount = wb.resolvedMethodRemovedCount();
-        } while (removedCountOrig == removedCount);
+          if (removedCountOrig != removedCount) {
+            break;
+          }
+          Thread.sleep(100);
+        }
       }
     }
 
     public static void test(String gc) throws Throwable {
-       // Run this Leak class with logging
+        // Run this Leak class with logging
         ProcessBuilder pb = ProcessTools.createJavaProcessBuilder(
                                       "-Xlog:membername+table=trace",
+                                      "-XX:+UnlockDiagnosticVMOptions",
                                       "-XX:+WhiteBoxAPI",
                                       "-Xbootclasspath/a:.",
                                       gc, Leak.class.getName());