G'Day,
This issue was news to me, and may be useful for readers of this list.
In brief:
USDT providers on MacOS X that are built with the -dead_strip linker option
have their probes fired twice by mistake. The workaround is not to use
the -dead_strip option.
Some more details:
After integration of the JavaScript DTrace provider into Firefox, the
Mozilla developers discovered that probes were firing twice by mistake -
so results such as @[probename]=count() were doubled.
The most likely reason was that probe placement had become incorrect -
during provider development the Firefox code was changing, and I had to
tweak the probe locations a few times. It sounded like more of the same,
but I couldn't see why this was happening in the code.
The Mozilla developers discovered it happened with the -dead_strip linker
option!:
https://bugzilla.mozilla.org/show_bug.cgi?id=403132
which from a quick search looks like it is a known issue:
http://www.opensource.apple.com/darwinsource/10.5/ld64-77/unit-tests/test-cases/dtrace-static-probes/Makefile
as -dead_strip is part of the Apple sanity checks.
That's all I know. If you know more details, please reply. :-) I also
don't know if this was fixed in the recent release of MacOS X (if it is
even considered a bug?).
cheers,
Brendan
--
Brendan
[CA, USA]
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