[英]Java JNA wrapper and memory consumption
I have a question how JVM processes with JNA wrappers show memory consumption. 我有一个疑问,带有JNA包装器的JVM进程如何显示内存消耗。
For example I run Java application which uses OpenCV JNA wrapper. 例如,我运行使用OpenCV JNA包装器的Java应用程序。 Java application itself consumes for example 1GB of RAM and OpenCV native libs consume 3GB of RAM.
Java应用程序本身消耗例如1GB的RAM,而OpenCV本机库消耗3GB的RAM。 So totally, when I will find appropriate Java JVM process(via
ps
command) it will show 1GB of RAM or 4GB(1 + 3) of RAM? 所以总的来说,当我找到合适的Java JVM进程(通过
ps
命令)时,它将显示1GB的RAM或4GB(1 + 3)的RAM?
Your ps
output will show 1GB for RSS (the Resident Set Size -- how much memory is allocated to that process and is in RAM.) The Java process will not directly show the used Native memory; 您的
ps
输出将显示1GB的RSS(“驻留集大小-分配给该进程并在RAM中的内存量”。)Java进程不会直接显示已用的本机内存; however, it will appear as a portion of the VSZ (Virtual Memory Size -- all memory that the process can access, including memory that is swapped out, memory that is allocated, but not used, and memory that is from shared libraries.) 但是,它将显示为VSZ的一部分(虚拟内存大小-进程可以访问的所有内存,包括换出的内存,已分配但未使用的内存以及来自共享库的内存。)
For example, I wrote the following code: 例如,我编写了以下代码:
import com.sun.jna.Memory;
public class TinyJavaBigC {
public static void main(String[] args) {
// Grab 1 GiB of memory
Memory buf = new Memory(1 << 30);
// Sleep long enough to grab ps
}
}
Regardless of the amount of Native memory reserved using new Memory(bytes)
(which effectively calls malloc
) the Java application consistently used the same amount memory in RSS, and limiting the Java heap size using -Xmx
did not prevent allocation of native memory beyond this limit. 不管使用
new Memory(bytes)
保留了多少本机内存(有效调用malloc
),Java应用程序始终在RSS中使用相同数量的内存,并且使用-Xmx
限制Java堆大小并不会阻止超出此范围的本机内存分配限制。 The 1 GiB of native memory clearly disappeared from the OS's "available" memory, however. 但是,本机内存的1 GiB显然已从操作系统的“可用”内存中消失了。
I placed the above code in a loop incrementing the shift left value for allocation, and ran it using -Xmx512m
which should have limited JVM heap to 512 MiB. 我将上面的代码放在循环中以增加左移值以进行分配,并使用
-Xmx512m
对其进行了-Xmx512m
,该-Xmx512m
应将JVM堆限制为512 MiB。 The RSS, which includes all JVM Stack and Heap Memory, remained in the ~50 MiB range. RSS(包括所有JVM堆栈和堆内存)保持在大约50 MiB范围内。 The allocated memory does show up in
VSZ
associated with the process. 分配的内存确实显示在与该进程关联的
VSZ
中。 As this also includes other types of memory it's not a direct measure, and vastly exceeds the available RAM and swapfile size constraints but it does at least give some indication of increased allocation. 由于这还包括其他类型的内存,因此这不是直接的衡量标准,并且大大超出了可用RAM和交换文件大小的限制,但至少确实表明了分配增加的迹象。
Native Memory RSS VSZ
1 byte 42.0 MiB 9.6 GiB
2 bytes 45.8 MiB 9.6 GiB
4 bytes 46.0 MiB 9.6 GiB
8 bytes 46.1 MiB 9.6 GiB
16 bytes 46.3 MiB 9.6 GiB
32 bytes 46.5 MiB 9.6 GiB
64 bytes 47.0 MiB 9.6 GiB
128 bytes 47.5 MiB 9.6 GiB
256 bytes 47.6 MiB 9.6 GiB
512 bytes 48.9 MiB 9.6 GiB
1 KiB 49.1 MiB 9.6 GiB
2 KiB 49.2 MiB 9.6 GiB
4 KiB 49.3 MiB 9.6 GiB
8 KiB 49.3 MiB 9.6 GiB
16 KiB 49.8 MiB 9.6 GiB
32 KiB 50.1 MiB 9.6 GiB
64 KiB 50.1 MiB 9.6 GiB
128 KiB 50.6 MiB 9.6 GiB
256 KiB 51.4 MiB 9.6 GiB
512 KiB 51.3 MiB 9.6 GiB
1 MiB 51.4 MiB 9.6 GiB
2 MiB 51.4 MiB 9.6 GiB
4 MiB 51.4 MiB 9.6 GiB
8 MiB 51.4 MiB 9.6 GiB
16 MiB 51.3 MiB 9.7 GiB
32 MiB 51.3 MiB 9.7 GiB
64 MiB 51.7 MiB 9.8 GiB
128 MiB 51.7 MiB 9.9 GiB
256 MiB 51.6 MiB 10.1 GiB
512 MiB 51.6 MiB 10.5 GiB
1 GiB 51.7 MiB 11.3 GiB
2 GiB 51.8 MiB 12.8 GiB
4 GiB 51.9 MiB 15.8 GiB
8 GiB 51.9 MiB 21.8 GiB
16 GiB 52.0 MiB 33.8 GiB
32 GiB 52.0 MiB 57.8 GiB
64 GiB 52.1 MiB 105.8 GiB
128 GiB 52.1 MiB 201.8 GiB
256 GiB 52.5 MiB 393.8 GiB
512 GiB 52.6 MiB 777.8 GiB
1 TiB 52.7 MiB 1.5 TiB
2 TiB 52.7 MiB 3.0 TiB
4 TiB 52.8 MiB 6.0 TiB
8 TiB 52.9 MiB 12.0 TiB
16 TiB 53.1 MiB 24.0 TiB
32 TiB 53.2 MiB 48.0 TiB
Exception in thread "main" java.lang.OutOfMemoryError: Cannot allocate 70368744177664 bytes
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