Any noticable impact on the binary code size?
--
- Milan
On Oct 3, 2014, at 16:12 , Eric Rahm <er...@mozilla.com> wrote:
> Hi all-
>
> In bug 806819 we're planning on landing a change that allows us to turn on
> NSPR logging in release builds [1]. To be clear, by default all logging
> output is disabled, this will just allow you to turn on logging via the same
> mechanisms [2] that have been available to debug builds and modules that
> already force logging to be enabled.
>
> Initial tests show no impact to performance, but of course it's possible
> there will be unforeseen regressions. Testing included all Talos tests,
> averaging of mochitest runtimes, and local ad-hoc performance measurements.
>
> Areas to look out for:
> * Logging being done in "hot" areas. PR_LOG is no longer a no-op so
> there is a slight amount of overhead with each logging call. If
> your output is truly debug only consider wrapping in a #ifdef DEBUG
> block.
> * Creating a log message and then logging it. PR_LOG supports printf
> style formatting, so you can save some overhead by using that
> rather than writing to your own buffer.
>
> For example, if you once had:
>
> #ifdef PR_LOGGING
> char* msg = expensiveFunction();
> PR_LOG(module, PR_LOG_DEBUG, (msg));
> #endif
>
> You'll want to move to:
>
> PR_LOG(module, PR_LOG_DEBUG, ("%s", expensiveFunction()));
>
> If you're interested in making logging better, please take a look at our meta
> bug [3] tracking various improvements. There's talk of making improvements to
> NSPR logging, ditching NSPR logging all together, adding streaming
> interfaces, switching log levels at runtime, and more. Feel free to join in
> the conversation.
>
> Please note: after this change you should never need to use FORCE_PR_LOG (and
> you'll probably get build errors if you do).
>
> A few side benefits:
> * All usage of FORCE_PR_LOG has been removed
> * Many more files are now eligible for unified building
>
> -e
>
> [1] https://bugzilla.mozilla.org/show_bug.cgi?id=806819
> [2]
> https://developer.mozilla.org/en-US/docs/Mozilla/Projects/NSPR/Reference/Logging
> [3] https://bugzilla.mozilla.org/show_bug.cgi?id=881389
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