RFR: 8146009: "pure virtual method called" with using new GC logging mechanism

[Thomas Stüfe]

Hi Markus,

just a question whether I understand this correctly: Logging works already
from static initialization on, but as no arguments are parsed yet, the
default is to print out all warning and error level messages to stderr?

If true, this may be potentially confusing, because there will always be a
small window at startup where logging does not behave as expected from the
command line arguments given. Like, if I redirect log output to a file, the
first burst of log output would still go to stderr. This may also confuse
tools which grep the output of a VM.

Additionally, during initialization one may actually want precise control
of the logging system before arguments are parsed, e.g. in os::init(). We
have a lot of tracing in the AIX os layer initialization which currently
goes to nil because it runs before Xlog argument parsing is done.

Both situations could be solved if there were a possibility to specify
logging options right from the start, e.g. via a file or an environment
variable, which could be parsed in a static initializer without relying on
any VM initialization.

Kind Regards, Thomas



On Mon, Oct 10, 2016 at 11:20 AM, Marcus Larsson <marcus.larsson at oracle.com>
wrote:

> Updated webrev after feedback:
> http://cr.openjdk.java.net/~mlarsson/8146009/webrev.01
>
> Incremental:
> http://cr.openjdk.java.net/~mlarsson/8146009/webrev.00-01
>
>
>
> On 10/07/2016 04:26 PM, Marcus Larsson wrote:
>
>> Hi,
>>
>> Making another attempt to fix this issue.
>>
>> Summary:
>> The following patch resolves a problem where the VM would crash during
>> shutdown due to static log related memory being de-initialized before the
>> last use of the logging framework. The solution involves parts of the Nifty
>> Counter idiom [0] to control static initialization and de-initialization of
>> stdout's and stderr's LogOutputs. Both objects are now allocated using
>> placement new, and avoids destructor calls during de-initialization. The
>> LogStreamInitializer makes sure both objects are initialized before first
>> use.
>>
>> Because the LogOutput::Stdout/err pointers could no longer be kept in
>> LogOutput, I've replaced all usages of them with the new references instead.
>>
>> The patch includes a regression test for this issue, contributed by
>> Michail Chernov.
>>
>> Webrev:
>> http://cr.openjdk.java.net/~mlarsson/8146009/webrev.00
>>
>> Issue:
>> https://bugs.openjdk.java.net/browse/JDK-8146009
>>
>> Testing:
>> JPRT testset hotspot, included test on supported platforms.
>>
>> Thanks,
>> Marcus
>>
>> [0] https://en.wikibooks.org/wiki/More_C%2B%2B_Idioms/Nifty_Counter
>>
>
>