RFR: 8029630: Print thread id hex representation in error messages.

Max Ockner max.ockner at oracle.com
Fri Apr 3 15:55:59 UTC 2015

Thanks for pointing out the flaw in thread.cpp. I will fix that.
I originally looked for an abstraction but couldn't find one. If you 
think it would be better to create a new format specifier, then I will 
do that as well.
On 4/3/2015 5:42 AM, Thomas Stüfe wrote:
> Hi Max,
> Disclaimer: not a Reviewer.
> In thread.cpp, the code prints the value of Thread* pointer, not a 
> thread id. So the code was correct before.
> That said, I find this pretty confusing, especially because it prints 
> "tid=<this>". Maybe one should change this or throw it away.
> --
> As for vmError.cpp: this seems to be correct.
> However, I would like to see this abstracted somehow, here is why:
> The OpenJDK simply assumes thread id to be 32bit unsigned. This is not 
> really portable and may bite us in the face (I am not sure if it 
> already did, was not thread id 64bit on AIX? at least for kernel 
> thread ids?).
> If you use pthread_t to implement thread id, like many ports do, 
> thread id may be anything - 64bit number, array, struct. POSIX leaves 
> that open.
> So, instead of a raw "%x", I propose as quick fix a format specifier 
> for thread ids, e.g. "THREAD_ID_FORMAT". That way we could at least 
> easily find all places where we print thread ids, if we later decide 
> to change the type for thread ids.
> Regards, Thomas
> On Thu, Apr 2, 2015 at 9:38 PM, Max Ockner <max.ockner at oracle.com 
> <mailto:max.ockner at oracle.com>> wrote:
>     Hello,
>     Please review this change:
>     Bug: https://bugs.openjdk.java.net/browse/JDK-8029630
>     Webrev: http://cr.openjdk.java.net/~mockner/8029630.2/
>     <http://cr.openjdk.java.net/%7Emockner/8029630.2/>
>     Summary: Existing error messages for vm crashes print the decimal
>     representation of the current thread id. The message format has
>     been changed to print the hex value of the thread id.
>     Tested with jtreg runtime to make sure nothing was broken. I
>     tested the new functionality separately. I crashed the vm and
>     examined the debugger output to make sure the hexadecimal thread
>     id printed in the error message matched one of the threads listed
>     by the debugger.
>     Thanks,
>     Max

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