java java.nio.ByteBuffer.allocateDirect 导致内存泄露
2012-12-26 11:11
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java能够经过 java.nio.ByteBuffer.allocateDirect(capacity) 直接运用non java heap(java堆外)的内存 。
2。能够打破jvm内存约束,操作更多的物理内存(不一样的jvm完成不一样,sun jvm会被约束,但能添加jvm能够操作的一倍内存,而jrockit基本上能够将物理内存悉数耗光)
public class ByteBufferTest {
public static void main(String[] args) throws InterruptedException {
System.out.println(SystemRuntimeInfo.getMemoryInfo());
List list = new ArrayList();
for(int i = 0; i < 100; i++) {
list.add(ByteBuffer.allocateDirect(Integer.MAX_VALUE / 100));
System.out.println(i + " " + SystemRuntimeInfo.getMemoryInfo()); // 个人写的内存占用东西类
}
System.out.println("start sleep,list.size() 唐山票:"+list.size());
Thread.sleep(100000);
System.out.println(list.size());
// java.nio.ByteBuffer.allocate(capacity) 运用 java heap(java堆)分配内存: 能够直接经过东西检查出内存占用
// java.nio.ByteBuffer.allocateDirect(capacity) 运用non java heap(非java堆)经过操作系统直接分配内存: 会招致检查不出java heap的内存占用,招致走漏看不出来
}
}
打印成果:
Java代码
----------------------
totalHeapMemory:15MB freeHeapMemory:14MB maxHeapMemory:247MB totalPhysicalMemorySize:2047MB freePhysicalMemorySize:1285MB usedPhysicalMemory:762MB
0 totalHeapMemory:15MB freeHeapMemory:14MB maxHeapMemory:247MB totalPhysicalMemorySize:2047MB freePhysicalMemorySize:1264MB usedPhysicalMemory:783MB
1 totalHeapMemory:15MB freeHeapMemory:14MB maxHeapMemory:247MB totalPhysicalMemorySize:2047MB freePhysicalMemorySize:1244MB usedPhysicalMemory:803MB
2 totalHeapMemory:15MB freeHeapMemory:14MB maxHeapMemory:247MB totalPhysicalMemorySize:2047MB freePhysicalMemorySize:1223MB usedPhysicalMemory:824MB
3 totalHeapMemory:15MB freeHeapMemory:14MB maxHeapMemory:247MB totalPhysicalMemorySize:2047MB freePhysicalMemorySize:1203MB usedPhysicalMemory:844MB
4 totalHeapMemory:15MB freeHeapMemory:14MB maxHeapMemory:247MB totalPhysicalMemorySize:2047MB freePhysicalMemorySize:1182MB usedPhysicalMemory:865MB
5 totalHeapMemory:15MB freeHeapMemory:14MB maxHeapMemory:247MB totalPhysicalMemorySize:2047MB freePhysicalMemorySize:1162MB usedPhysicalMemory:885MB
6 totalHeapMemory:15MB freeHeapMemory:14MB maxHeapMemory:247MB totalPhysicalMemorySize:2047MB freePhysicalMemorySize:1141MB usedPhysicalMemory:906MB
7 totalHeapMemory:15MB freeHeapMemory:14MB maxHeapMemory:247MB totalPhysicalMemorySize:2047MB freePhysicalMemorySize:1121MB usedPhysicalMemory:926MB
8 totalHeapMemory:15MB freeHeapMemory:14MB maxHeapMemory:247MB totalPhysicalMemorySize:2047MB freePhysicalMemorySize:1100MB usedPhysicalMemory:947MB
9 totalHeapMemory:15MB freeHeapMemory:14MB maxHeapMemory:247MB totalPhysicalMemorySize:2047MB freePhysicalMemorySize:1079MB usedPhysicalMemory:968MB
VisualVM内存检查:
Heap内存分配
实践java进程内存占用:
经过VisualVM能够发现,java heap底子没有运用,但java进程的物理内存现已运用400MB+
1. 运用ByteBuffer.allocateDirect()分配出去的内存无法经过Heap检查
2. ByteBuffer.allocateDirect()分配的内容能够被GC收回,但走漏的话较难查找
一.运用意图:
1。拓荒数据缓冲区2。能够打破jvm内存约束,操作更多的物理内存(不一样的jvm完成不一样,sun jvm会被约束,但能添加jvm能够操作的一倍内存,而jrockit基本上能够将物理内存悉数耗光)
二.运用难题:
经过ByteBuffer.allocateDirect()运用的内存不能够经过jvm关联内存东西:VisualVM等检查heap的内存占用,所以内存走漏也较难查找。三. 测验如下:
Java代码public class ByteBufferTest {
public static void main(String[] args) throws InterruptedException {
System.out.println(SystemRuntimeInfo.getMemoryInfo());
List list = new ArrayList();
for(int i = 0; i < 100; i++) {
list.add(ByteBuffer.allocateDirect(Integer.MAX_VALUE / 100));
System.out.println(i + " " + SystemRuntimeInfo.getMemoryInfo()); // 个人写的内存占用东西类
}
System.out.println("start sleep,list.size() 唐山票:"+list.size());
Thread.sleep(100000);
System.out.println(list.size());
// java.nio.ByteBuffer.allocate(capacity) 运用 java heap(java堆)分配内存: 能够直接经过东西检查出内存占用
// java.nio.ByteBuffer.allocateDirect(capacity) 运用non java heap(非java堆)经过操作系统直接分配内存: 会招致检查不出java heap的内存占用,招致走漏看不出来
}
}
打印成果:
Java代码
----------------------
totalHeapMemory:15MB freeHeapMemory:14MB maxHeapMemory:247MB totalPhysicalMemorySize:2047MB freePhysicalMemorySize:1285MB usedPhysicalMemory:762MB
0 totalHeapMemory:15MB freeHeapMemory:14MB maxHeapMemory:247MB totalPhysicalMemorySize:2047MB freePhysicalMemorySize:1264MB usedPhysicalMemory:783MB
1 totalHeapMemory:15MB freeHeapMemory:14MB maxHeapMemory:247MB totalPhysicalMemorySize:2047MB freePhysicalMemorySize:1244MB usedPhysicalMemory:803MB
2 totalHeapMemory:15MB freeHeapMemory:14MB maxHeapMemory:247MB totalPhysicalMemorySize:2047MB freePhysicalMemorySize:1223MB usedPhysicalMemory:824MB
3 totalHeapMemory:15MB freeHeapMemory:14MB maxHeapMemory:247MB totalPhysicalMemorySize:2047MB freePhysicalMemorySize:1203MB usedPhysicalMemory:844MB
4 totalHeapMemory:15MB freeHeapMemory:14MB maxHeapMemory:247MB totalPhysicalMemorySize:2047MB freePhysicalMemorySize:1182MB usedPhysicalMemory:865MB
5 totalHeapMemory:15MB freeHeapMemory:14MB maxHeapMemory:247MB totalPhysicalMemorySize:2047MB freePhysicalMemorySize:1162MB usedPhysicalMemory:885MB
6 totalHeapMemory:15MB freeHeapMemory:14MB maxHeapMemory:247MB totalPhysicalMemorySize:2047MB freePhysicalMemorySize:1141MB usedPhysicalMemory:906MB
7 totalHeapMemory:15MB freeHeapMemory:14MB maxHeapMemory:247MB totalPhysicalMemorySize:2047MB freePhysicalMemorySize:1121MB usedPhysicalMemory:926MB
8 totalHeapMemory:15MB freeHeapMemory:14MB maxHeapMemory:247MB totalPhysicalMemorySize:2047MB freePhysicalMemorySize:1100MB usedPhysicalMemory:947MB
9 totalHeapMemory:15MB freeHeapMemory:14MB maxHeapMemory:247MB totalPhysicalMemorySize:2047MB freePhysicalMemorySize:1079MB usedPhysicalMemory:968MB
VisualVM内存检查:
Heap内存分配
实践java进程内存占用:
经过VisualVM能够发现,java heap底子没有运用,但java进程的物理内存现已运用400MB+
四.测验定论:
1. 运用ByteBuffer.allocateDirect()分配出去的内存无法经过Heap检查
2. ByteBuffer.allocateDirect()分配的内容能够被GC收回,但走漏的话较难查找
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