JEP 271: Unified GC Logging - Third pre-review
bengt.rutisson at oracle.com
Mon Nov 16 12:17:14 UTC 2015
On 2015-11-13 19:49, Kirk Pepperdine wrote:
> Hi Bengt,
> GC(5) seems to be missing. from
Good catch. This is a problem with the way CMS (or rather
GenCollectedHeap) can skip a young GC and directly kick off a full
collection if it finds that the young collection would fail. The way
GenCollectedHeap::do_collection() handles the two types of collections
that it can start is too complex in my opinion.
This is the same code that makes this log:
look like collection number 5 and 3 come in the wrong order.
(See the "Even more details..." section in my first pre-review:
I will file an RFE to fix this but it is not really a logging problem.
It is more of a code structure problem. So, I would like to fix this
separately after the big unified logging change has been pushed. The new
logging just makes it more visible.
>> On Nov 13, 2015, at 9:56 AM, Bengt Rutisson
>> <bengt.rutisson at oracle.com <mailto:bengt.rutisson at oracle.com>> wrote:
>> Hi everyone,
>> Here is an updated pre-review for the work for JEP 271 Unified GC
>> Now it includes all the logging that I plan on converting for the
>> first step.
>> Here are examples from the latest prototype:
>> The webrev for the changes is available here:
>> Some changes that have been made:
>> - GC id is now logged as "GC(5)" instead of the previous "GC#5"
>> - The CMS and G1 concurrent logging have been homogenized to look
>> similar. All concurrent phases are start with "Concurrent" and now
>> include timestamps.
>> - The paused phases now all start with "Pause".
>> - The log messages from the different collectors now look more
>> similar. For example "Pause Young" is used for young GCs for all
>> collectors instead of for example "Young pause" for G1 and "Pause.
>> ParNew" for CMS.
>> - I've added a line at the start of the log to clearly state what GC
>> is selected.
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