Please review fix to StackOverflowError in jigsaw tracing

[Alan Bateman]

Mandy Chung wrote:
> I have a fix for:
>   6951456: jigsaw JIGSAW_TRACE=3 stack overflow due to recursion
>
> Trace may be called while the classes for tracing (e.g. 
> java.util.Formatter)
> are being loaded. One solution is to cache the traces to avoid recursion
> until the very first call completes.
>
> Webrev at:
>   http://cr.openjdk.java.net/~mchung/6951456/webrev.00/
>
> Thanks
> Mandy
I didn't see any replies to this so I've looked at the webrev.

I realize tracing isn't critical but it looks like there is potential to 
buffer messages that will never be printed. Say thread A observes that 
we are initializing just before thread B sets the inited flag. Maybe the 
simplest is to replace "calls" with an initializing flag that is only 
accessed when holding a lock. That would ensure that you can't buffer a 
trace message after the buffered messages have been flushed.

Minor comment but would two Lists be a more appropriate collection for 
the buffered messages?  Also when calling Cache.trace when maybe you 
could do this:

sb.append(fmt);
sb.append("%n");
Cache.trace(sb.toString(), args);

-Alan.