| /* |
| * Copyright 2009 Google Inc. |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); you may not |
| * use this file except in compliance with the License. You may obtain a copy of |
| * the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT |
| * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the |
| * License for the specific language governing permissions and limitations under |
| * the License. |
| */ |
| package com.google.gwt.dev.util; |
| |
| import java.io.File; |
| import java.lang.management.ManagementFactory; |
| import java.lang.reflect.Method; |
| |
| /** |
| * Utility methods for dealing with VM memory. |
| */ |
| public class Memory { |
| |
| /** |
| * Number of times to call System.gc() before measuring the memory |
| * usage/dumping the heap. This value was arrived at through trial-and-error |
| * on the Sun JVM; memory usage seems to stabilize after 3 to 4 runs. We think |
| * the reason it requires multiple runs is due to the generational aspect of |
| * garbage collection. |
| */ |
| private static final int NUM_GC_COLLECTIONS = 4; |
| |
| /** |
| * Set this system property to a filename suffix to dump heaps into. |
| */ |
| private static final String PROPERTY_DUMP_HEAP = "gwt.memory.dumpHeap"; |
| |
| /** |
| * Set this system property to dump memory usage at various points. |
| */ |
| private static final String PROPERTY_DUMP_MEMORY = "gwt.memory.usage"; |
| |
| /** |
| * Time to start measuring since the last memory measurement/dump, or |
| * application startup. |
| */ |
| private static long startTime; |
| |
| public static void initialize() { |
| if (System.getProperty(PROPERTY_DUMP_MEMORY) != null) { |
| System.out.println("Will print mem usage"); |
| } |
| if (System.getProperty(PROPERTY_DUMP_HEAP) != null) { |
| System.out.println("Will dump heap into: *-" |
| + System.getProperty(PROPERTY_DUMP_HEAP)); |
| } |
| startTime = System.currentTimeMillis(); |
| } |
| |
| public static void main(String[] args) { |
| initialize(); |
| System.setProperty(PROPERTY_DUMP_MEMORY, ""); |
| maybeDumpMemory("test"); |
| } |
| |
| public static void maybeDumpMemory(String info) { |
| long elapsed = System.currentTimeMillis() - startTime; |
| if (System.getProperty(PROPERTY_DUMP_MEMORY) != null) { |
| for (int i = 0; i < NUM_GC_COLLECTIONS; ++i) { |
| System.gc(); |
| } |
| long heap = ManagementFactory.getMemoryMXBean().getHeapMemoryUsage().getUsed(); |
| long nonHeap = ManagementFactory.getMemoryMXBean().getNonHeapMemoryUsage().getUsed(); |
| String infoString = String.format("[%.18s]", info); |
| System.out.println(String.format( |
| "%-20s %10d heap, %10d nonheap, %10d total, %10.2fs", infoString, |
| heap, nonHeap, heap + nonHeap, (double) elapsed / 1000)); |
| } |
| String dumpFile = System.getProperty(PROPERTY_DUMP_HEAP); |
| if (dumpFile != null) { |
| String procName = ManagementFactory.getRuntimeMXBean().getName(); |
| dumpFile = info + "-" + procName + dumpFile; |
| new File(dumpFile).delete(); |
| try { |
| Class<?> beanClass = Class.forName("com.sun.management.HotSpotDiagnosticMXBean"); |
| Object bean = ManagementFactory.newPlatformMXBeanProxy( |
| ManagementFactory.getPlatformMBeanServer(), |
| "com.sun.management:type=HotSpotDiagnostic", beanClass); |
| Method dumpHeapMethod = beanClass.getDeclaredMethod("dumpHeap", |
| String.class, Boolean.TYPE); |
| dumpHeapMethod.invoke(bean, dumpFile, true); |
| System.out.println("(" + info + ") dumped heap into: " + dumpFile); |
| } catch (Throwable e) { |
| System.err.println("Unable to dump heap"); |
| e.printStackTrace(); |
| } |
| } |
| // Reset for next call |
| startTime = System.currentTimeMillis(); |
| } |
| } |