On 10/3/14 1:12 PM, Eric Rahm 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
This has landed, so far one issue has been reported for VS2013 builds [1] that has a pending solution for the underlying problem, this is not related to enabling logging but was exposed as part of the effort to get files added back in to unified compilation.
Many files were added back into unified compilation that were explicitly excluded due to "NSPR logging" and "uses FORCE_PR_LOG (those are the terms I searched for), if you know of others that may not have been as easily found please follow up and add them back into the UNIFIED_SOURCES.
Also of course, don't use FORCE_PR_LOG anymore. You'll most likely get -Werror failures due to redefined macros. Please check your pending patches!
-e [1] https://bugzilla.mozilla.org/show_bug.cgi?id=1080297 _______________________________________________ dev-platform mailing list [email protected] https://lists.mozilla.org/listinfo/dev-platform
