Review request (XS): JDK-8009282: Assertion "assert(used_and_free == capacity_bytes) failed: Accounting is wrong" failed with -XX:+Verbose -XX:+TraceMetadataChunkAllocation

[Mikael Gerdin]

Hi,

Please review this small fix for an incorrect assert that can trigger 
when we run out of metaspace memory.

Webrev:
http://cr.openjdk.java.net/~mgerdin/8009282/webrev.0/


The reasoning behind this change is that when running with the command 
line flags specified in the bug report we call MetaspaceAux::print_on 
when we're about to throw an j.l.OutOfMemoryError. At that point another 
thread may be successful in allocating metaspace memory in another class 
loader or smaller memory chunks which are available.

The assert condition must only hold when the VM is at a safe point and 
no other thread may be allocating metaspace memory.

Thanks
/Mikael