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

[Florian Weimer]

On 03/26/2015 04:14 PM, Evan Jones wrote:
> At Twitter, I recently discovered that the hsperfdata file that is created
> by default by the JVM causes long safepoint and GC pauses. It turns out
> that writes to mmap-ed files can block until disk I/O completes, even if
> the I/O is to another disk. For details see:
> http://www.evanjones.ca/jvm-mmap-pause.html

Can you try to get a kernel backtrace when this happens?  Preferably on
ext4 or XFS.

Scheduling a page for writeback probably requires a kernel memory
allocation, so this behavior isn't too surprising.

-- 
Florian Weimer / Red Hat Product Security