JEP 141: Increase the Client VM's Default Heap Size

Sunny Chan openjdk at
Wed Feb 29 00:21:29 PST 2012

Jon Masamitsu <jon.masamitsu at ...> writes:

> Sunny,
> We've talked about the fallback position of trying to reserve
> less that the default (say, 1G).  Would you want it all to be done
> silently?  Or would you want some warning that your
> not getting the whole 1G?   Or would you want a flag
> (yet another flag, ugh) that you turn on that would cause
> a warning?
> Jon

I think others should chime in on this, but the way I think about this 
is that 32bit Client VM are most likely running GUI applications, and 
generally they don't see any error message you push out onto the console. 
So unless your warning is going to be a message box pop up, no one would 
ever notice until they hit OutOfMemoryError.

If an application doesn't specify a Xmx or Xms value, it is really 
telling the JVM that it doesn't really care what the sizings of the heap 
are and they are hoping the default would work. So as long as the fall back 
position is well known and well defined (e.g. JVM will try 1G and then 512M, 
then it will fail with a helpful message), then I don't think it would cause 
too many problems.

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