2

系统信息

操作系统：archlinux

JDK：OpenJDK (IcedTea 2.4.3) (ArchLinux build 7.u45_2.4.3-1-x86_64)

运行应用：https ://github.com/aemoncannon/ensime

我的Java选项：

-Xms128m -Xmx512M -Xss1M -XX:MaxPermSize=50m 
-XX:MaxDirectMemorySize=10M  
-XX:ReservedCodeCacheSize=64m 
-Dfile.encoding=UTF-8 -XX:NativeMemoryTracking=detai

Linux top 命令显示，它使用 6.8G * 19.5% = 1.326GB

Natvie 内存跟踪显示它使用了 713MB

所以。哪一个是实际的物理内存使用量，如果使用1.3GB内存，那额外的600+MB物理内存去哪儿了？

顶级输出

top - 09:20:37 up 48 min,  2 users,  load average: 0.31, 0.33, 0.36
Tasks: 161 total,   1 running, 159 sleeping,   0 stopped,   1 zombie
%Cpu(s):  0.7 us,  0.3 sy,  0.0 ni, 99.0 id,  0.0 wa,  0.0 hi,  0.0 si,  0.0 
KiB Mem:   7091684 total,  4338428 used,  2753256 free,   117044 buffers
KiB Swap:  8388604 total,        0 used,  8388604 free,  1399904 cached

  PID USER      PR  NI    VIRT    RES    SHR S  %CPU %MEM     TIME+ COMMAND  
 5666 jilen     20   0 3553516 1.317g  22652 S   0.3 19.5   2:27.72 java

本机内存跟踪输出（jcmd VM.native_memory detail）

Native Memory Tracking:

Total:  reserved=731125KB,  committed=681117KB

-                 Java Heap (reserved=575488KB, committed=574976KB)
                            (mmap: reserved=575488KB, committed=574976KB)

-                     Class (reserved=6388KB, committed=6388KB)
                            (classes #6443)
                            (malloc=6388KB, #16725)

-                    Thread (reserved=27986KB, committed=27986KB)
                            (thread #27)
                            (stack: reserved=27756KB, committed=27756KB)
                            (malloc=82KB, #114)
                            (arena=148KB, #54)

-                      Code (reserved=70523KB, committed=21059KB)
                            (malloc=3963KB, #6149)
                            (mmap: reserved=66560KB, committed=17096KB)

-                        GC (reserved=26964KB, committed=26964KB)
                            (malloc=5900KB, #158)
                            (mmap: reserved=21064KB, committed=21064KB)

-                  Compiler (reserved=176KB, committed=176KB)
                            (malloc=78KB, #238)
                            (arena=98KB, #2)

-                  Internal (reserved=5463KB, committed=5431KB)
                            (malloc=5431KB, #1492)
                            (mmap: reserved=32KB, committed=0KB)

-                    Symbol (reserved=10668KB, committed=10668KB)
                            (malloc=9765KB, #77949)
                            (arena=903KB, #1)

-           Memory Tracking (reserved=5616KB, committed=5616KB)
                            (malloc=5616KB, #120)

-        Pooled Free Chunks (reserved=1854KB, committed=1854KB)
                            (malloc=1854KB)


Virtual memory map:

[0x00000000dce00000 - 0x0000000100000000] reserved 575488KB for Java Heap
        from [JVM_handle_linux_signal+0x173dbd]
    [0x00000000dce00000 - 0x00000000fff80000] committed 574976KB from [JVM_handle_linux_signal+0x650ab]

[0x00007f53801c7000 - 0x00007f53802c8000] reserved 1028KB for Thread Stack
        from [JVM_handle_linux_signal+0x12f2ec]
    [0x00007f53801c7000 - 0x00007f53802c8000] committed 1028KB from [JVM_handle_linux_signal+0x12f2ec]

[0x00007f5381daf000 - 0x00007f5381eb0000] reserved 1028KB for Thread Stack
        from [JVM_handle_linux_signal+0x12f2ec]
    [0x00007f5381daf000 - 0x00007f5381eb0000] committed 1028KB from [JVM_handle_linux_signal+0x12f2ec]

[0x00007f53821f0000 - 0x00007f53824f3000] reserved 3084KB for Thread Stack
        from [JVM_handle_linux_signal+0x12f2ec]
    [0x00007f53821f0000 - 0x00007f53824f3000] committed 3084KB from [JVM_handle_linux_signal+0x12f2ec]

[0x00007f5382d49000 - 0x00007f5382e4a000] reserved 1028KB for Thread Stack
        from [JVM_handle_linux_signal+0x12f2ec]
    [0x00007f5382d49000 - 0x00007f5382e4a000] committed 1028KB from [JVM_handle_linux_signal+0x12f2ec]

[0x00007f538302a000 - 0x00007f538342e000] reserved 4112KB for Thread Stack
        from [JVM_handle_linux_signal+0x12f2ec]
    [0x00007f538302a000 - 0x00007f538342e000] committed 4112KB from [JVM_handle_linux_signal+0x12f2ec]

[0x00007f53b47c7000 - 0x00007f53b4aca000] reserved 3084KB for Thread Stack
        from [JVM_handle_linux_signal+0x12f2ec]
    [0x00007f53b47c7000 - 0x00007f53b4aca000] committed 3084KB from [JVM_handle_linux_signal+0x12f2ec]

[0x00007f53b4db7000 - 0x00007f53b4eb8000] reserved 1028KB for Thread Stack
        from [JVM_handle_linux_signal+0x127be9]
    [0x00007f53b4db7000 - 0x00007f53b4eb8000] committed 1028KB from [JVM_handle_linux_signal+0x127be9]

[0x00007f53b4eb8000 - 0x00007f53b52bc000] reserved 4112KB for Thread Stack
        from [JVM_handle_linux_signal+0x12f2ec]
    [0x00007f53b4eb8000 - 0x00007f53b52bc000] committed 4112KB from [JVM_handle_linux_signal+0x12f2ec]

[0x00007f53b5894000 - 0x00007f53b5a96000] reserved 2056KB for Thread Stack
        from [JVM_handle_linux_signal+0x12f2ec]
    [0x00007f53b5894000 - 0x00007f53b5a96000] committed 2056KB from [JVM_handle_linux_signal+0x12f2ec]

[0x00007f53b5a96000 - 0x00007f53b5b97000] reserved 1028KB for Thread Stack
        from [JVM_handle_linux_signal+0x17c90d]
    [0x00007f53b5a96000 - 0x00007f53b5b97000] committed 1028KB from [JVM_handle_linux_signal+0x17c90d]

[0x00007f53b5b97000 - 0x00007f53b5c98000] reserved 1028KB for Thread Stack
        from [JVM_FindSignal+0x118f1b]
    [0x00007f53b5b97000 - 0x00007f53b5c98000] committed 1028KB from [JVM_FindSignal+0x118f1b]

[0x00007f53b6e70000 - 0x00007f53b8000000] reserved 17984KB for GC
        from [JVM_handle_linux_signal+0x172529]
    [0x00007f53b6e70000 - 0x00007f53b8000000] committed 17984KB from [JVM_handle_linux_signal+0x650ab]

[0x00007f53c4000000 - 0x00007f53c8000000] reserved 65536KB for Code
        from [JVM_handle_linux_signal+0x1741a5]
    [0x00007f53c4000000 - 0x00007f53c5070000] committed 16832KB from [JVM_handle_linux_signal+0x1746f4]

[0x00007f53cc0e4000 - 0x00007f53cc1fd000] reserved 1124KB for GC
        from [JVM_handle_linux_signal+0x172529]
    [0x00007f53cc0e4000 - 0x00007f53cc1fd000] committed 1124KB from [JVM_handle_linux_signal+0x650ab]

[0x00007f53cc1fd000 - 0x00007f53cc601000] reserved 4112KB for Thread Stack
        from [AsyncGetCallTrace+0x3949c]
    [0x00007f53cc1fd000 - 0x00007f53cc601000] committed 4112KB from [AsyncGetCallTrace+0x3949c]

[0x00007f53cc601000 - 0x00007f53cc71b000] reserved 1128KB for GC
        from [JVM_handle_linux_signal+0x172529]
    [0x00007f53cc601000 - 0x00007f53cc71b000] committed 1128KB from [dlerror+0x3aad37]

[0x00007f53cc71b000 - 0x00007f53cc81b000] reserved 1024KB for Code
        from [JVM_handle_linux_signal+0x172289]
    [0x00007f53cc71b000 - 0x00007f53cc75d000] committed 264KB from [JVM_handle_linux_signal+0x1746f4]

[0x00007f53cf497000 - 0x00007f53cf4a2000] reserved 44KB for GC
        from [JVM_handle_linux_signal+0x172529]
    [0x00007f53cf497000 - 0x00007f53cf54d000] committed 728KB from [JVM_handle_linux_signal+0x650ab]

[0x00007f53cf4a2000 - 0x00007f53cf54d000] reserved 684KB for GC
        from [JVM_handle_linux_signal+0x172289]

[0x00007f53cf54d000 - 0x00007f53cf64e000] reserved 1028KB for Thread Stack
        from [JVM_handle_linux_signal+0x12c997]
    [0x00007f53cf54d000 - 0x00007f53cf64e000] committed 1028KB from [JVM_handle_linux_signal+0x12c997]

[0x00007f53cf656000 - 0x00007f53cf66f000] reserved 100KB for GC
        from [JVM_handle_linux_signal+0x172289]
    [0x00007f53cf656000 - 0x00007f53cf66f000] committed 100KB from [JVM_handle_linux_signal+0x650ab]

[0x00007f53cf66f000 - 0x00007f53cf677000] reserved 32KB for Internal
        from [JVM_handle_linux_signal+0x3c924]

Details:

[0x00007f53ce330855] JVM_handle_linux_signal+0xee085
                            (malloc=6627KB #77628)

[0x00007f53ce291061] JVM_handle_linux_signal+0x4e891
                            (malloc=5120KB #5)

[0x00007f53ce293021] JVM_handle_linux_signal+0x50851
                            (malloc=5120KB #5)

[0x00007f53ce2a19b5] JVM_handle_linux_signal+0x5f1e5
                            (malloc=5120KB #5)

[0x00007f53ce1c8c64] JVM_FindSignal+0x1188f4
                            (malloc=4040KB #1)

[0x00007f53cde99851] dlerror+0x409851
                            (malloc=3903KB #5678)

[0x00007f53cdd2dcb3] dlerror+0x29dcb3
                            (malloc=2643KB #148)

[0x00007f53cdff5b86] AsyncGetCallTrace+0x6dc46
                            (malloc=2512KB #314)

[0x00007f53ce1c0b17] JVM_FindSignal+0x1107a7
                            (malloc=1274KB #106)

[0x00007f53ce291149] JVM_handle_linux_signal+0x4e979
                            (malloc=640KB #5)

[0x00007f53ce233375] JVM_FindSignal+0x183005
                            (malloc=524KB #419)

[0x00007f53ce38c670] JVM_handle_linux_signal+0x149ea0
                            (malloc=469KB #1)

[0x00007f53cde87c53] dlerror+0x3f7c53
                            (malloc=408KB #16085)

[0x00007f53cdd2d142] dlerror+0x29d142
                            (malloc=360KB #1)

[0x00007f53cdff5186] AsyncGetCallTrace+0x6d246
                            (malloc=310KB #25)

[0x00007f53ce38c581] JVM_handle_linux_signal+0x149db1
                            (malloc=156KB #1)

[0x00007f53cdd38523] dlerror+0x2a8523
                            (malloc=127KB #681)

[0x00007f53ce1c5acb] JVM_FindSignal+0x11575b
                            (malloc=96KB #2)

[0x00007f53ce1c807e] JVM_FindSignal+0x117d0e
                            (malloc=96KB #1)

[0x00007f53ce38e0e4] JVM_handle_linux_signal+0x14b914
                            (malloc=80KB #5)

[0x00007f53ce368abd] JVM_handle_linux_signal+0x1262ed
                            (malloc=71KB #25)

[0x00007f53ce1b4c27] JVM_FindSignal+0x1048b7
                            (malloc=64KB #16)

[0x00007f53ce1b4c97] JVM_FindSignal+0x104927
                            (malloc=64KB #16)

[0x00007f53ce25c867] JVM_handle_linux_signal+0x1a097
                            (malloc=55KB #116)

[0x00007f53ce1c0584] JVM_FindSignal+0x110214
                            (malloc=51KB #1)

[0x00007f53ce1c5a15] JVM_FindSignal+0x1156a5
                            (malloc=48KB #1)

[0x00007f53cdea0fc3] dlerror+0x410fc3
                            (malloc=37KB #464)

[0x00007f53cdf169bd] dlerror+0x4869bd
                            (malloc=36KB #13)

[0x00007f53ce3b2aa7] JVM_handle_linux_signal+0x1702d7
                            (malloc=24KB #13)

[0x00007f53cdff6496] AsyncGetCallTrace+0x6e556
                            (malloc=20KB #4)

[0x00007f53cdeb2ff3] dlerror+0x422ff3
                            (malloc=17KB #180)

[0x00007f53ce27ba1b] JVM_handle_linux_signal+0x3924b
                            (malloc=15KB #255)

[0x00007f53ce368b9d] JVM_handle_linux_signal+0x1263cd
                            (malloc=10KB #1)

[0x00007f53ce367fdb] JVM_handle_linux_signal+0x12580b
                            (malloc=8KB #47)

[0x00007f53cdff2df5] AsyncGetCallTrace+0x6aeb5
                            (malloc=8KB #11)

[0x00007f53cdf5d7d4] dlerror+0x4cd7d4
                            (malloc=8KB #1)

[0x00007f53ce289bc4] JVM_handle_linux_signal+0x473f4
                            (malloc=8KB #1)

[0x00007f53ce2059d6] JVM_FindSignal+0x155666
                            (malloc=7KB #62)

[0x00007f53ce27bb04] JVM_handle_linux_signal+0x39334
                            (malloc=7KB #251)

[0x00007f53ce242453] fork1+0x52b3
                            (malloc=6KB #28)

[0x00007f53ce024918] AsyncGetCallTrace+0x9c9d8
                            (malloc=5KB #18)

[0x00007f53cdd2d333] dlerror+0x29d333
                            (malloc=2KB #57)

[0x00007f53ce36a598] JVM_handle_linux_signal+0x127dc8
                            (malloc=2KB #1)

[0x00007f53ce2d6e24] JVM_handle_linux_signal+0x94654
                            (malloc=2KB #1)

[0x00007f53ce290d96] JVM_handle_linux_signal+0x4e5c6
                            (malloc=2KB #5)

[0x00007f53ce2a1536] JVM_handle_linux_signal+0x5ed66
                            (malloc=2KB #5)

[0x00007f53ce25a49b] JVM_handle_linux_signal+0x17ccb
                            (malloc=2KB #7)

[0x00007f53cde881eb] dlerror+0x3f81eb
                            (malloc=1KB #15)

[0x00007f53ce171720] JVM_FindSignal+0xc13b0
                            (malloc=1KB #74)

[0x00007f53cdf5ef54] dlerror+0x4cef54
                            (malloc=1KB #1)

[0x00007f53cde8a8aa] dlerror+0x3fa8aa
                            (malloc=1KB #59)

[0x00007f53ce3b658d] JVM_handle_linux_signal+0x173dbd
                            (mmap: reserved=575488KB, committed=574976KB)

[0x00007f53ce3b6975] JVM_handle_linux_signal+0x1741a5
                            (mmap: reserved=65536KB, committed=16832KB)

[0x00007f53ce3b4cf9] JVM_handle_linux_signal+0x172529
                            (mmap: reserved=20280KB, committed=20280KB)

[0x00007f53ce371abc] JVM_handle_linux_signal+0x12f2ec
                            (mmap: reserved=19532KB, committed=19532KB)

[0x00007f53cdfc13dc] AsyncGetCallTrace+0x3949c
                            (mmap: reserved=4112KB, committed=4112KB)

[0x00007f53ce3b4a59] JVM_handle_linux_signal+0x172289
                            (mmap: reserved=1808KB, committed=1048KB)

[0x00007f53ce1c928b] JVM_FindSignal+0x118f1b
                            (mmap: reserved=1028KB, committed=1028KB)

[0x00007f53ce36a3b9] JVM_handle_linux_signal+0x127be9
                            (mmap: reserved=1028KB, committed=1028KB)

[0x00007f53ce36f167] JVM_handle_linux_signal+0x12c997
                            (mmap: reserved=1028KB, committed=1028KB)

[0x00007f53ce3bf0dd] JVM_handle_linux_signal+0x17c90d
                            (mmap: reserved=1028KB, committed=1028KB)

[0x00007f53ce27f0f4] JVM_handle_linux_signal+0x3c924
                            (mmap: reserved=32KB, committed=0KB)
4

1 回答 1

3

RES 或 %MEM 值是物理内存的实际使用量。

因为您的系统完全没有内存压力，所以不会尝试恢复物理内存。这是因为这样的努力是一个失败的提议。如果内存没有很快用于其他目的，那么释放它的努力就会被浪费掉。如果内存很快被用于其他目的，释放它的努力比浪费更糟糕，它必须撤消才能再次使用内存。当需要内存时，现代操作系统直接将内存从一种用途转换为另一种用途，而无需释放该内存。只有在别无选择时才会释放内存。

因此，基本上，物理内存会暂时被浪费，直到系统可以找到更好的用途。如果您在机器上运行其他一些消耗物理内存的任务，您将看到 RES 和 %MEM 值随着物理内存转换为其他用途而下降。

于 2013-11-27T01:50:31.610 回答