hsperfdata causing long GC/safepoint times: Don't use mmap?

Dean Long dean.long at oracle.com
Thu Mar 26 21:33:35 UTC 2015

On 3/26/2015 2:25 PM, Evan Jones wrote:
> On Thu, Mar 26, 2015 at 4:15 PM, Dean Long <dean.long at oracle.com 
> <mailto:dean.long at oracle.com>> wrote:
>     I'm curious, does the problem go away if the mmap doesn't use
> That is a variant I did not try, however for the JVM stats I don't 
> think that would work. Doesn't MAP_PRIVATE mean that the modifications 
> to the mmap-ed file are not written back to disk? The point of this 
> shared file is that other tools can read the statistics.

Looks like you're right.  For some reason I was thinking that there was 
something in between MAP_SHARED and MAP_PRIVATE, where other processes 
would only be guaranteed to see the changes after the fd was closed.


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