8006088: Incompatible heap size flags accepted by VM

Summary: Make processing of minimum, initial and maximum heap size more intiutive by removing previous limitations on allowed values, and make error reporting consistent. Further, fix errors in ergonomic heap sizing.
Reviewed-by: johnc, jwilhelm, tamao

src/share/vm/memory/collectorPolicy.cpp

@@ -55,6 +55,10 @@ void CollectorPolicy::initialize_flags() {
       err_msg("max_alignment: " SIZE_FORMAT " not aligned by min_alignment: " SIZE_FORMAT,
           max_alignment(), min_alignment()));
 
+  if (MaxHeapSize < InitialHeapSize) {
+    vm_exit_during_initialization("Incompatible initial and maximum heap sizes specified");
+  }
+
   if (MetaspaceSize > MaxMetaspaceSize) {
     MaxMetaspaceSize = MetaspaceSize;
   }
@@ -78,21 +82,9 @@ void CollectorPolicy::initialize_flags() {
 }
 
 void CollectorPolicy::initialize_size_info() {
-  // User inputs from -mx and ms are aligned
-  set_initial_heap_byte_size(InitialHeapSize);
-  if (initial_heap_byte_size() == 0) {
-    set_initial_heap_byte_size(NewSize + OldSize);
-  }
-  set_initial_heap_byte_size(align_size_up(_initial_heap_byte_size,
-                                           min_alignment()));
-
-  set_min_heap_byte_size(Arguments::min_heap_size());
-  if (min_heap_byte_size() == 0) {
-    set_min_heap_byte_size(NewSize + OldSize);
-  }
-  set_min_heap_byte_size(align_size_up(_min_heap_byte_size,
-                                       min_alignment()));
-
+  // User inputs from -mx and ms must be aligned
+  set_min_heap_byte_size(align_size_up(Arguments::min_heap_size(), min_alignment()));
+  set_initial_heap_byte_size(align_size_up(InitialHeapSize, min_alignment()));
   set_max_heap_byte_size(align_size_up(MaxHeapSize, max_alignment()));
 
   // Check heap parameter properties
@@ -237,9 +229,6 @@ void TwoGenerationCollectorPolicy::initialize_flags() {
   GenCollectorPolicy::initialize_flags();
 
   OldSize = align_size_down(OldSize, min_alignment());
-  if (NewSize + OldSize > MaxHeapSize) {
-    MaxHeapSize = NewSize + OldSize;
-  }
 
   if (FLAG_IS_CMDLINE(OldSize) && FLAG_IS_DEFAULT(NewSize)) {
     // NewRatio will be used later to set the young generation size so we use
@@ -254,6 +243,27 @@ void TwoGenerationCollectorPolicy::initialize_flags() {
   }
   MaxHeapSize = align_size_up(MaxHeapSize, max_alignment());
 
+  // adjust max heap size if necessary
+  if (NewSize + OldSize > MaxHeapSize) {
+    if (FLAG_IS_CMDLINE(MaxHeapSize)) {
+      // somebody set a maximum heap size with the intention that we should not
+      // exceed it. Adjust New/OldSize as necessary.
+      uintx calculated_size = NewSize + OldSize;
+      double shrink_factor = (double) MaxHeapSize / calculated_size;
+      // align
+      NewSize = align_size_down((uintx) (NewSize * shrink_factor), min_alignment());
+      // OldSize is already aligned because above we aligned MaxHeapSize to
+      // max_alignment(), and we just made sure that NewSize is aligned to
+      // min_alignment(). In initialize_flags() we verified that max_alignment()
+      // is a multiple of min_alignment().
+      OldSize = MaxHeapSize - NewSize;
+    } else {
+      MaxHeapSize = NewSize + OldSize;
+    }
+  }
+  // need to do this again
+  MaxHeapSize = align_size_up(MaxHeapSize, max_alignment());
+
   always_do_update_barrier = UseConcMarkSweepGC;
 
   // Check validity of heap flags

src/share/vm/prims/whitebox.cpp

@@ -93,6 +93,15 @@ WB_ENTRY(jboolean, WB_IsClassAlive(JNIEnv* env, jobject target, jstring name))
   return closure.found();
 WB_END
 
+WB_ENTRY(void, WB_PrintHeapSizes(JNIEnv* env, jobject o)) {
+  CollectorPolicy * p = Universe::heap()->collector_policy();
+  gclog_or_tty->print_cr("Minimum heap "SIZE_FORMAT" Initial heap "
+    SIZE_FORMAT" Maximum heap "SIZE_FORMAT" Min alignment "SIZE_FORMAT" Max alignment "SIZE_FORMAT,
+    p->min_heap_byte_size(), p->initial_heap_byte_size(), p->max_heap_byte_size(),
+    p->min_alignment(), p->max_alignment());
+}
+WB_END
+
 #if INCLUDE_ALL_GCS
 WB_ENTRY(jboolean, WB_G1IsHumongous(JNIEnv* env, jobject o, jobject obj))
   G1CollectedHeap* g1 = G1CollectedHeap::heap();
@@ -386,6 +395,7 @@ static JNINativeMethod methods[] = {
       CC"(Ljava/lang/String;[Lsun/hotspot/parser/DiagnosticCommand;)[Ljava/lang/Object;",
       (void*) &WB_ParseCommandLine
   },
+  {CC"printHeapSizes",     CC"()V",                   (void*)&WB_PrintHeapSizes    },
 #if INCLUDE_ALL_GCS
   {CC"g1InConcurrentMark", CC"()Z",                   (void*)&WB_G1InConcurrentMark},
   {CC"g1IsHumongous",      CC"(Ljava/lang/Object;)Z", (void*)&WB_G1IsHumongous     },

src/share/vm/runtime/arguments.cpp

@@ -1617,19 +1617,19 @@ void Arguments::set_heap_size() {
     FLAG_SET_ERGO(uintx, MaxHeapSize, (uintx)reasonable_max);
   }
 
-  // If the initial_heap_size has not been set with InitialHeapSize
-  // or -Xms, then set it as fraction of the size of physical memory,
-  // respecting the maximum and minimum sizes of the heap.
-  if (FLAG_IS_DEFAULT(InitialHeapSize)) {
+  // If the minimum or initial heap_size have not been set or requested to be set
+  // ergonomically, set them accordingly.
+  if (InitialHeapSize == 0 || min_heap_size() == 0) {
     julong reasonable_minimum = (julong)(OldSize + NewSize);
 
     reasonable_minimum = MIN2(reasonable_minimum, (julong)MaxHeapSize);
 
     reasonable_minimum = limit_by_allocatable_memory(reasonable_minimum);
 
+    if (InitialHeapSize == 0) {
       julong reasonable_initial = phys_mem / InitialRAMFraction;
 
-    reasonable_initial = MAX2(reasonable_initial, reasonable_minimum);
+      reasonable_initial = MAX3(reasonable_initial, reasonable_minimum, (julong)min_heap_size());
       reasonable_initial = MIN2(reasonable_initial, (julong)MaxHeapSize);
 
       reasonable_initial = limit_by_allocatable_memory(reasonable_initial);
@@ -1637,10 +1637,18 @@ void Arguments::set_heap_size() {
       if (PrintGCDetails && Verbose) {
         // Cannot use gclog_or_tty yet.
         tty->print_cr("  Initial heap size " SIZE_FORMAT, (uintx)reasonable_initial);
-      tty->print_cr("  Minimum heap size " SIZE_FORMAT, (uintx)reasonable_minimum);
       }
       FLAG_SET_ERGO(uintx, InitialHeapSize, (uintx)reasonable_initial);
-    set_min_heap_size((uintx)reasonable_minimum);
+    }
+    // If the minimum heap size has not been set (via -Xms),
+    // synchronize with InitialHeapSize to avoid errors with the default value.
+    if (min_heap_size() == 0) {
+      set_min_heap_size(MIN2((uintx)reasonable_minimum, InitialHeapSize));
+      if (PrintGCDetails && Verbose) {
+        // Cannot use gclog_or_tty yet.
+        tty->print_cr("  Minimum heap size " SIZE_FORMAT, min_heap_size());
+      }
+    }
   }
 }
 
@@ -2426,7 +2434,8 @@ jint Arguments::parse_each_vm_init_arg(const JavaVMInitArgs* args,
     // -Xms
     } else if (match_option(option, "-Xms", &tail)) {
       julong long_initial_heap_size = 0;
-      ArgsRange errcode = parse_memory_size(tail, &long_initial_heap_size, 1);
+      // an initial heap size of 0 means automatically determine
+      ArgsRange errcode = parse_memory_size(tail, &long_initial_heap_size, 0);
       if (errcode != arg_in_range) {
         jio_fprintf(defaultStream::error_stream(),
                     "Invalid initial heap size: %s\n", option->optionString);
@@ -2437,7 +2446,7 @@ jint Arguments::parse_each_vm_init_arg(const JavaVMInitArgs* args,
       // Currently the minimum size and the initial heap sizes are the same.
       set_min_heap_size(InitialHeapSize);
     // -Xmx
-    } else if (match_option(option, "-Xmx", &tail)) {
+    } else if (match_option(option, "-Xmx", &tail) || match_option(option, "-XX:MaxHeapSize=", &tail)) {
       julong long_max_heap_size = 0;
       ArgsRange errcode = parse_memory_size(tail, &long_max_heap_size, 1);
       if (errcode != arg_in_range) {

src/share/vm/runtime/globals.hpp

@@ -2968,7 +2968,7 @@ class CommandLineFlags {
                                                                             \
   /* gc parameters */                                                       \
   product(uintx, InitialHeapSize, 0,                                        \
-          "Initial heap size (in bytes); zero means OldSize + NewSize")     \
+          "Initial heap size (in bytes); zero means use ergonomics")        \
                                                                             \
   product(uintx, MaxHeapSize, ScaleForWordSize(96*M),                       \
           "Maximum heap size (in bytes)")                                   \

test/testlibrary/whitebox/sun/hotspot/WhiteBox.java

@@ -61,6 +61,9 @@ public class WhiteBox {
     registerNatives();
   }
 
+  // Arguments
+  public native void printHeapSizes();
+
   // Memory
   public native long getObjectAddress(Object o);
   public native int  getHeapOopSize();