[Info-vax] help needed diagnosing/debugging java.lang.OutOfMemoryError

[Arne Vajhøj]

On 8/18/2011 5:15 PM, Arne Vajhøj wrote:
> On 8/18/2011 8:43 AM, VAXman- @SendSpamHere.ORG wrote:
>> In article<4e4c6bba$0$308$14726298 at news.sunsite.dk>,
>> =?ISO-8859-1?Q?Arne_Vajh=F8j?=<arne at vajhoej.dk> writes:
>>> On 8/17/2011 8:23 AM, VAXman- @SendSpamHere.ORG wrote:
>>>> In article<4e4b2601$0$314$14726298 at news.sunsite.dk>,
>>>> =?ISO-8859-1?Q?Arne_Vajh=F8j?=<arne at vajhoej.dk> writes:
>>>>> On 8/16/2011 9:59 PM, VAXman- @SendSpamHere.ORG wrote:
>>>>>> In article<4e4b055e$0$314$14726298 at news.sunsite.dk>,
>>>>>> =?ISO-8859-1?Q?Arne_Vajh=F8j?=<arne at vajhoej.dk> writes:
>>>>>>> On 8/16/2011 9:07 AM, VAXman- @SendSpamHere.ORG wrote:
>>>>>>>> In article<4e49c081$0$314$14726298 at news.sunsite.dk>,
>>>>>>>> =?ISO-8859-1?Q?Arne_Vajh=F8j?=<arne at vajhoej.dk> writes:
>>>>>>>>> On 8/15/2011 8:43 PM, VAXman- @SendSpamHere.ORG wrote:
>>>>>>>>>> In article<4e4994ad$0$312$14726298 at news.sunsite.dk>,
>>>>>>>>>> =?ISO-8859-1?Q?Arne_Vajh=F8j?=<arne at vajhoej.dk> writes:
>>>>>>>>>>> On 8/15/2011 2:11 PM, VAXman- @SendSpamHere.ORG wrote:
>>>>>>>>>>>> What the subject says...
>>>>>>>>>>>>
>>>>>>>>>>>> An application in development for use on an OpenVMS system
>>>>>>>>>>>> is tossing up
>>>>>>>>>>>> this error. I've increased the page file quota for
>>>>>>>>>>>> APACHE$WWW to 1M and
>>>>>>>>>>>> there is still this error. The logs produced by this Java
>>>>>>>>>>>> stuff do not
>>>>>>>>>>>> tell much. Is there some way to get a dump or more logging?
>>>>>>>>>>>>
>>>>>>>>>>>> PS. I don't do Java (unless it's in my coffee mug) and thus,
>>>>>>>>>>>> I'm not the
>>>>>>>>>>>> one developing the app.
>>>>>>>>>>>
>>>>>>>>>>> First: 512 MB is not that much today.
>>>>>>>>>>>
>>>>>>>>>>> Second: what value does the -Xmx option for the java command?
>>>>>>>>>>> (it also
>>>>>>>>>>> limits the maximum memory that can be allocated)
>>>>>>>>>>
>>>>>>>>>> Well, it pukes with -Xmx384m
>>>>>>>>>
>>>>>>>>> Then try 512m 768m 1024m (and make sure that there is backing
>>>>>>>>> for it).
>>>>>>>>
>>>>>>>> The STARTUP pukes @ -Xmx384m complaining about memory.
>>>>>>>
>>>>>>> Does the account starting the app have more
>>>>>>> than 384 MB available (page file quota)?
>>>>>>
>>>>>> SYSTEM account has 2000000 on this particular machine. That's a
>>>>>> gig in
>>>>>> my book.
>>>>>
>>>>> Yup.
>>>>>
>>>>> What exactly does "pukes" mean?
>>>>
>>>> the out of memory errors.
>>>>
>>>>> And what Java version?
>>>>
>>>> 1.5.07 This is on Alpha.
>>>
>>> Does it run with 768m?
>>
>> If Java won't start with more than 256m and the application pukes on
>> that,
>> there's little chance of 768m.
>
> ????
>
> java.lang.OutOfMemoryError means that the apps code can not allocate
> the desired memory from the Java heap.
>
> Xmx limits the size of the Java heap.
>
> So in case of java.lang.OutOfMemoryError the first thing to try is to
> increase Xmx.
>
> If the JVM can not get Xmx from VMS, then you will get a different
> type of error.

Example:

$ type mm.java
public class MM {
     public static void main(String[] args) {
         try {
             int n = Integer.parseInt(args[0]);
             System.out.println(n + " MB");
             byte[] b = new byte[n*1024*1024];
             System.out.println("It works");
         } catch(Throwable t) {
             System.out.println(t);
         }
     }
}
$ javac mm.java
$ java "-Xmx50m" "MM" 100
100 MB
java.lang.OutOfMemoryError
$ java "-Xmx150m" "MM" 100
100 MB
It works
$ java "-Xmx1500m" "MM" 100
-Xmx1500m: value out of range 8192..943718400
Could not create the Java virtual machine.

Arne