# HG changeset patch
# User stuefe
# Date 1562055900 -7200
# Node ID e846a51e8966d70e3c15ef0c75306940fc3655bd
# Parent  448d63614b6b8ad0e636f6d0a2fb6feb2eb0fc62
8227035: JVM::printFlags fails in native OOM situations
Reviewed-by: goetz, gziemski

diff -r 448d63614b6b -r e846a51e8966 src/hotspot/share/runtime/flags/jvmFlag.cpp
--- a/src/hotspot/share/runtime/flags/jvmFlag.cpp	Mon Jul 01 17:08:04 2019 -0700
+++ b/src/hotspot/share/runtime/flags/jvmFlag.cpp	Tue Jul 02 10:25:00 2019 +0200
@@ -1475,19 +1475,13 @@
 
 void JVMFlag::printFlags(outputStream* out, bool withComments, bool printRanges, bool skipDefaults) {
   // Print the flags sorted by name
-  // note: this method is called before the thread structure is in place
-  //       which means resource allocation cannot be used.
+  // Note: This method may be called before the thread structure is in place
+  //       which means resource allocation cannot be used. Also, it may be
+  //       called as part of error reporting, so handle native OOMs gracefully.
 
   // The last entry is the null entry.
   const size_t length = JVMFlag::numFlags - 1;
 
-  // Sort
-  JVMFlag** array = NEW_C_HEAP_ARRAY(JVMFlag*, length, mtArguments);
-  for (size_t i = 0; i < length; i++) {
-    array[i] = &flagTable[i];
-  }
-  qsort(array, length, sizeof(JVMFlag*), compare_flags);
-
   // Print
   if (!printRanges) {
     out->print_cr("[Global flags]");
@@ -1495,12 +1489,28 @@
     out->print_cr("[Global flags ranges]");
   }
 
-  for (size_t i = 0; i < length; i++) {
-    if (array[i]->is_unlocked() && !(skipDefaults && array[i]->is_default())) {
-      array[i]->print_on(out, withComments, printRanges);
+  // Sort
+  JVMFlag** array = NEW_C_HEAP_ARRAY_RETURN_NULL(JVMFlag*, length, mtArguments);
+  if (array != NULL) {
+    for (size_t i = 0; i < length; i++) {
+      array[i] = &flagTable[i];
+    }
+    qsort(array, length, sizeof(JVMFlag*), compare_flags);
+
+    for (size_t i = 0; i < length; i++) {
+      if (array[i]->is_unlocked() && !(skipDefaults && array[i]->is_default())) {
+        array[i]->print_on(out, withComments, printRanges);
+      }
+    }
+    FREE_C_HEAP_ARRAY(JVMFlag*, array);
+  } else {
+    // OOM? Print unsorted.
+    for (size_t i = 0; i < length; i++) {
+      if (flagTable[i].is_unlocked() && !(skipDefaults && flagTable[i].is_default())) {
+        flagTable[i].print_on(out, withComments, printRanges);
+      }
     }
   }
-  FREE_C_HEAP_ARRAY(JVMFlag*, array);
 }
 
 void JVMFlag::printError(bool verbose, const char* msg, ...) {