RFR: JDK-8149541: Use log_error() instead of log_info() when verification reports a problem

[Bengt Rutisson]

Hi everyone,

Could I have a couple of reviews for this change?

http://cr.openjdk.java.net/~brutisso/8149541/webrev.00/
https://bugs.openjdk.java.net/browse/JDK-8149541

When the GC code was converted to use the unified logging framework the 
verification logging was changed to mostly use:

log_info(gc, vefiy)("Information about verification failure");

The problem with this is that some verification, in particular in G1, 
does not report the relevant information in asserts and guarnatee 
messages. Instead the information is logged ahead of time and at some 
later point there is something like a "guarantee(false, "Verification 
failed.");"

So, to know what went wrong you really need the information that was 
logged. However when it is logged on log_info(gc, verify) you need to 
have remembered to set -Xlog:gc* on the command line to get this 
information.

A better solution is to log failure information at the error level. That 
way it is always logged.

Thanks,
Bengt