RFR: 8146879: Truncate new UL log files

[Marcus Larsson]

Hi,

On 01/14/2016 09:36 PM, ecki at zusammenkunft.net wrote:
> Hello,
>
> Especially for the GC log it is bad if the file is lost after a restart. It is of course possible to include PID or timestamp into the logfile, and then the truncation is no option, however if you do that you have to do your own purging. If you just want a number of generations with a fixed filename the truncation is not very good, Generally speaking why would you want to tru cate anyway? (You always have the option to delete the files if you want to feel the start,) but in all automated scenarios I cant see a good reason for truncating existing logs.
>
> So it should be at least an option to truncate.

I can see some use cases for appending to the log files, but I think the 
expected behavior is that files should be truncated. I believe it's 
worth keeping optional though, so we could add an option for log files 
whether or not they should be truncated before used (with the default 
being truncating). This way we also keep the previous behavior of -Xloggc.

> (And if you do that, I dont think using append mode is needed).

External log rotation tools require us to use append mode to work 
correctly, and we should do so regardless of truncation settings.

Thanks,
Marcus

>
> Gruss
> Bernd
>