bugGNU Octave - Bugs: bug #53943, memory usage explodes on a...


bug #53943: memory usage explodes on a javaMethod call

Submitter:  A.R. Burgers <arb>
Submitted:  Sat 19 May 2018 02:07:30 PM UTC
Category:  Interpreter Severity:  2 - Minor
Priority:  5 - Normal Item Group:  Performance
Status:  Works For Me Assigned to:  None
Originator Name:  Open/Closed:  * Closed
Release:  * dev Operating System:  * GNU/Linux
Fixed Release:  None Planned Release:  None
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Mon 20 Aug 2018 02:04:16 PM UTC, comment #4: 

for the record:

  • there is no Octave bug here.

  • The java VM heap size can be controlled in octave with a java.opts file as documented in the manual section "Passing parameters to the JVM"

A.R. Burgers <arb>
Tue 05 Jun 2018 01:18:21 AM UTC, comment #3: 

Do you agree that Java is behaving as documented and there is no Octave bug here?

Mike Miller <mtmiller>
Group Member
Mon 21 May 2018 07:18:06 PM UTC, comment #2: 

Here is I think a relevant discussion of this topic:


The 35Gb is 1/4 of the physical memory of 145Gb, which is the default MaxHeapSize

java -XX:+PrintFlagsFinal -version | grep HeapSize
    uintx ErgoHeapSizeLimit                         = 0               {product}
    uintx HeapSizePerGCThread                       = 87241520        {product}
    uintx InitialHeapSize                          := 2147483648      {product}
    uintx LargePageHeapSizeThreshold                = 134217728       {product}
    uintx MaxHeapSize                              := 32126271488     {product}
java version "1.7.0_161"
Java(TM) SE Runtime Environment (build 1.7.0_161-b13)
Java HotSpot(TM) 64-Bit Server VM (build 24.161-b13, mixed mode)

A.R. Burgers <arb>
Sun 20 May 2018 11:45:45 PM UTC, comment #1: 

This looks to me like the expected behavior of Java, the amount of memory that Java uses is outside of Octave's control.

FWIW I see the following numbers on my system.

  • octave-cli --norc uses about 650 MiB
  • octave --norc uses about 1,322 MiB
  • a standalone C program that creates a Java VM uses about 6,584 MiB
  • octave-cli --norc after loading a Java VM uses about 8,387 MiB
  • octave --norc after loading a Java VM uses about 9.037 MiB

The baseline memory difference between octave-cli and octave-gui is about 650 MiB. This is the same before and after Java is loaded.

The memory difference on my system due to starting a Java VM in Octave is about 7,730 MiB. This is slightly larger than the memory used by a simple C program that just creates a Java VM, but not much different.

So on my system I see a large increase of about 7.7 GiB when Octave creates a Java VM, but not the 34 GiB increase that you are seeing. This may be due to system configuration differences or a different version or build of Java.

You might try measuring the memory usage of a simple Java hello world program. On my system with the same version of Java, I see a memory usage of about 6.7 GiB, which is consistent with the other examples I tested.

Mike Miller <mtmiller>
Group Member
Sat 19 May 2018 02:07:30 PM UTC, original submission:  

with this script, that basically has one line invoking a javaMethod,

ver = version
hg_id = __octave_config_info__.hg_id

m_before = memory
dynamic_path = javaMethod ("getClassPath", "org.octave.ClassHelper")
m_after = memory

The memory.m file can be found here:


The script outputs:

ver = 5.0.0
hg_id = 75fef3484d12+
m_before =

  scalar structure containing the fields:

    total =  660.15
    rss =  63.684
    shared =  28.328
    data =  194.57
    physical =  145319.24609

dynamic_path =
m_after =

  scalar structure containing the fields:

    total =  34653.17969
    rss =  91.375
    shared =  35.656
    data =  34165.11328
    physical =  145319.24609

Memory foot print jumps to 35 Gb. The jump is not limited to dev.

I noticed this phenomenon during an xlsopen from the io package, and narrowed it down to this line.

A.R. Burgers <arb>


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    Follow 3 latest changes.

    Date Changed by Updated Field Previous Value => Replaced by
    2018-06-06 mtmiller Open/ClosedOpen Closed
    2018-05-20 mtmiller Severity3 - Normal 2 - Minor
        StatusNone Works For Me

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