diff -r c97db0855565 -r 758c07667682 src/share/vm/memory/genCollectedHeap.cpp
--- a/src/share/vm/memory/genCollectedHeap.cpp	Tue Feb 04 17:38:01 2020 +0800
+++ b/src/share/vm/memory/genCollectedHeap.cpp	Tue Feb 04 18:13:14 2020 +0800
@@ -796,8 +796,11 @@
 #else  // INCLUDE_ALL_GCS
     ShouldNotReachHere();
 #endif // INCLUDE_ALL_GCS
-  } else if (cause == GCCause::_wb_young_gc) {
-    // minor collection for WhiteBox API
+  } else if ((cause == GCCause::_wb_young_gc) ||
+             (cause == GCCause::_gc_locker)) {
+    // minor collection for WhiteBox or GCLocker.
+    // _gc_locker collections upgraded by GCLockerInvokesConcurrent
+    // are handled above and never discarded.
     collect(cause, 0);
   } else {
 #ifdef ASSERT
@@ -835,6 +838,11 @@
   // Read the GC count while holding the Heap_lock
   unsigned int gc_count_before      = total_collections();
   unsigned int full_gc_count_before = total_full_collections();
+
+  if (GC_locker::should_discard(cause, gc_count_before)) {
+    return;
+  }
+
   {
     MutexUnlocker mu(Heap_lock);  // give up heap lock, execute gets it back
     VM_GenCollectFull op(gc_count_before, full_gc_count_before,
@@ -887,24 +895,16 @@
 
 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs,
                                           int max_level) {
-  int local_max_level;
-  if (!incremental_collection_will_fail(false /* don't consult_young */) &&
-      gc_cause() == GCCause::_gc_locker) {
-    local_max_level = 0;
-  } else {
-    local_max_level = max_level;
-  }
 
   do_collection(true                 /* full */,
                 clear_all_soft_refs  /* clear_all_soft_refs */,
                 0                    /* size */,
                 false                /* is_tlab */,
-                local_max_level      /* max_level */);
+                max_level            /* max_level */);
   // Hack XXX FIX ME !!!
   // A scavenge may not have been attempted, or may have
   // been attempted and failed, because the old gen was too full
-  if (local_max_level == 0 && gc_cause() == GCCause::_gc_locker &&
-      incremental_collection_will_fail(false /* don't consult_young */)) {
+  if (gc_cause() == GCCause::_gc_locker && incremental_collection_failed()) {
     if (PrintGCDetails) {
       gclog_or_tty->print_cr("GC locker: Trying a full collection "
                              "because scavenge failed");