RFR(s): 8149036: Add UL tracing for thread related events at os level

[Coleen Phillimore]

Thank you for separating the issues and for the comments in bug 
https://bugs.openjdk.java.net/browse/JDK-8148425 which makes it clearer 
the problems with strerror().

If David approves or you have another reviewer, I'll sponsor it.

Coleen


On 2/23/16 4:24 AM, Thomas Stüfe wrote:
> Hi Coleen,
>
> thank you for the review!
>
> See here the new webrev:
>
> http://cr.openjdk.java.net/~stuefe/webrevs/8149036-add-tracing-for-thread-events/webrev.01/webrev/index.html 
> <http://cr.openjdk.java.net/%7Estuefe/webrevs/8149036-add-tracing-for-thread-events/webrev.01/webrev/index.html>
>
> Ok, to separate the logging from the strerror issue, I replaced the 
> offending calls to os::errno_name() with plain strerror() on the base 
> that this is the way we do it now all over the hotspot (although we 
> know it is broken). I do not like much adding broken code to broken 
> code, but all alternatives (strerror_s, os::lasterror()) I like even less.
>
> As for the strerror issue, this may be a larger discussion, so I added 
> my comments to the bug David opened.
>
> Kind Regards, Thomas
>
>
> On Tue, Feb 23, 2016 at 12:09 AM, Coleen Phillimore 
> <coleen.phillimore at oracle.com <mailto:coleen.phillimore at oracle.com>> 
> wrote:
>
>
>     Oh, also, I am willing to sponsor this.
>     Thanks,
>     Coleen
>
>
>     On 2/22/16 5:45 PM, Coleen Phillimore wrote:
>
>
>
>         On 2/22/16 3:53 PM, Coleen Phillimore wrote:
>
>
>             Hi Thomas,
>             I think the logging conversion looks really good. The
>             errno stuff is very ugly though.  Can you call strerrno_r
>             - the thread safe version?  I didn't see discussion around
>             this.
>
>
>         Hi Thomas, I was talking to Kim.  You should use strerror()
>         and not add this code to os.cpp. The rationale is in this bug:
>
>         https://bugs.openjdk.java.net/browse/JDK-6223913
>
>         It seems like the errors would have standard errno at this
>         point and wouldn't be susceptible to the race in strerror().
>
>         +        log.warning("Failed to start thread - pthread_create
>         failed (%s) for attributes: %s.",
>         +          os::errno_name(errno),
>         os::Posix::describe_pthread_attr(buf, sizeof(buf), &attr));
>
>         It seems the chance of a race creating different errno at this
>         early point in the jvm is very low.
>
>         Coleen
>
>             Thanks,
>             Coleen
>
>             On 2/22/16 11:54 AM, Thomas Stüfe wrote:
>
>                 Dear all,
>
>                 please take a look at this proposed addition to UL.
>                 This adds a number of
>                 trace points to thread creation. In detail:
>
>                 - it traces thread creation and thread creation
>                 errors, including pthread
>                 attributes (for Posix platforms)
>                 - it traces stack location and creation/removal of
>                 stack guard pages.
>
>                 This all was first AIX-only tracing, but I converted
>                 this to UL and made it
>                 available on all platforms.
>
>                 Bug: https://bugs.openjdk.java.net/browse/JDK-8149036
>                 Webrev:
>                 http://cr.openjdk.java.net/~stuefe/webrevs/8149036-add-tracing-for-thread-events/webrev.00/webrev/
>                 <http://cr.openjdk.java.net/%7Estuefe/webrevs/8149036-add-tracing-for-thread-events/webrev.00/webrev/>
>
>
>                 Note also that I added a helper function,
>                 os::errno_name(), which is a very
>                 simple replacement for strerror() without its problems
>                 (thread safety,
>                 unwanted localizations...).
>
>                 What do you think?
>
>                 Kind Regards, Thomas
>
>
>
>
>