8277631: ZGC: CriticalMetaspaceAllocation asserts

Reviewed-by: pliden, stefank, dholmes

Author: fisk

src/hotspot/share/memory/metaspaceCriticalAllocation.cpp

@@ -113,19 +113,25 @@ void MetaspaceCriticalAllocation::remove(MetadataAllocationRequest* request) {
 }
 
 bool MetaspaceCriticalAllocation::try_allocate_critical(MetadataAllocationRequest* request) {
-  MutexLocker ml(MetaspaceCritical_lock, Mutex::_no_safepoint_check_flag);
-  if (_requests_head == request) {
-    // The first request can't opportunistically ride on a previous GC
-    return false;
+  {
+    MutexLocker ml(MetaspaceCritical_lock, Mutex::_no_safepoint_check_flag);
+    if (_requests_head == request) {
+      // The first request can't opportunistically ride on a previous GC
+      return false;
+    }
   }
   // Try to ride on a previous GC and hope for early satisfaction
   wait_for_purge(request);
   return request->result() != NULL;
 }
 
 void MetaspaceCriticalAllocation::wait_for_purge(MetadataAllocationRequest* request) {
-  while (!request->has_result()) {
-    ThreadBlockInVM tbivm(JavaThread::current());
+  ThreadBlockInVM tbivm(JavaThread::current());
+  MutexLocker ml(MetaspaceCritical_lock, Mutex::_no_safepoint_check_flag);
+  for (;;) {
+    if (request->has_result()) {
+      break;
+    }
     MetaspaceCritical_lock->wait_without_safepoint_check();
   }
 }

test/hotspot/jtreg/vmTestbase/gc/gctests/LoadUnloadGC/LoadUnloadGC.java

@@ -28,11 +28,11 @@
  * @summary converted from VM Testbase gc/gctests/LoadUnloadGC.
  * VM Testbase keywords: [gc, stress, stressopt, nonconcurrent, monitoring]
  * VM Testbase readme:
- * In this test a 1000 classes are loaded and unloaded in a loop.
+ * In this test 1000 classes are loaded and unloaded in a loop.
  * Class0 gets loaded which results in Class1 getting loaded and so on all
- * the way uptill class1000.  The classes should be unloaded whenever a
+ * the way up to class1000.  The classes should be unloaded whenever a
  * garbage collection takes place because their classloader is made unreachable
- * at the end of the each loop iteration. The loop is repeated 1000 times.
+ * at the end of each loop iteration. The loop is repeated 1000 times.
  *
  * @requires vm.opt.final.ClassUnloading
  * @library /vmTestbase
@@ -45,6 +45,30 @@
  *      gc.gctests.LoadUnloadGC.LoadUnloadGC
  */
 
+/*
+ * @test
+ * @key stress
+ *
+ * @summary converted from VM Testbase gc/gctests/LoadUnloadGC.
+ * VM Testbase keywords: [gc, stress, stressopt, nonconcurrent, monitoring]
+ * VM Testbase readme:
+ * In this test 1000 classes are loaded and unloaded in a loop.
+ * Class0 gets loaded which results in Class1 getting loaded and so on all
+ * the way up to class1000.  The classes should be unloaded whenever a
+ * garbage collection takes place because their classloader is made unreachable
+ * at the end of each loop iteration. The loop is repeated 1000 times.
+ *
+ * @requires vm.opt.final.ClassUnloading
+ * @library /vmTestbase
+ *          /test/lib
+ * @build nsk.share.gc.ClassChain
+ * @run main/othervm
+ *      -XX:MaxMetaspaceSize=64M
+ *      -XX:MetaspaceSize=64M
+ *      -XX:CompressedClassSpaceSize=32M
+ *      gc.gctests.LoadUnloadGC.LoadUnloadGC
+ */
+
 package gc.gctests.LoadUnloadGC;
 
 import nsk.share.test.*;