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Re: Where am I?

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Arne Vajhøj wrote:
> On 10/13/2011 6:16 AM, Arved Sandstrom wrote:
>> On 11-10-12 09:23 PM, Stanimir Stamenkov wrote:
>>> Wed, 12 Oct 2011 17:04:50 -0700, /Roedy Green/:
>>>> It would be nice for debugging to include the line number of where the
>>>> code is when printing out the error message.  Is there a simple way to
>>>> get it, or do you need to create a Throwable then analyse the
>>>> stacktrace?
>>>
>>> I guess one could also use Thread.currentThread().getStackTrace():
>>>
>>> http://download.oracle.com/javase/6/docs/api/java/lang/Thread.html#getStackTrace%28%29 
>>>
>>>
>>>
>>> But how's the current code line useful in such a log?  If you see the
>>> exact message you probably already know (or could easily find) where in
>>> the source it is produced.  If the same message is logged from different
>>> locations, probably the message should be revised to be more specific as
>>> appropriate?
>> [ SNIP ]
>>
>> I agree 100%. In production Java applications that I help maintain or
>> write, line numbers only feature in the error logs, and that's because
>> we dump the full stack trace into the error log if there was a serious
>> enough exception. For logging at any other level (info, warn, debug etc)
>> the message format we have devised, and simply having a descriptive
>> enough message, always pinpoints the location in the source. At worst
>> you might have to do an indirect search in a properties file for a
>> message key, then grep the source for that key, but that's like 10 extra
>> seconds.
>>
>> We (I) happen to usually use log4j, and in the API docs for log4j
>> PatternLayout, there are warnings about using the conversion specifiers
>> for class name, file name, method name and line number, because they are
>> slow or extremely slow. Since you don't actually need to compute any of
>> these if you do what Stanimir suggests, why take the hit?
>>
>> This observation - about making the debugging message descriptive
>> enough, without using computed source location information, to identify
>> the location of the message - is applicable not just to use of a logger
>> like log4j, but also quick and dirty println's or printf's. For example,
>> if doing some throwaway printf's, I usually include a string of form
>> "classname.methodname: " in the message.
> 
> The problem with that approach is that it is designing the
> logging based on an assumption that developers will do what they
> are supposed to do. That assumption is not always true.

Another way of looking at this is as a matter of where to put the burden
of making sure the message can always be tracked back to the code that
logged it, on the programmer or on the logging infrastructure.

In general, the more of the routine work that has to be done all over
the place the infrastructure can manage the better. At a minimum, it
saves programmer time and thinking for things the infrastructure cannot
handle. It is especially important for code that may not be heavily
tested - some log messages result from conditions that should never happen.

Patricia

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Thread

Where am I? Roedy Green <see_website@mindprod.com.invalid> - 2011-10-12 17:04 -0700
  Re: Where am I? Daniel Pitts <newsgroup.nospam@virtualinfinity.net> - 2011-10-12 17:22 -0700
    Re: Where am I? bugbear <bugbear@trim_papermule.co.uk_trim> - 2011-10-13 09:36 +0100
      Re: Where am I? Arne Vajhøj <arne@vajhoej.dk> - 2011-10-13 17:00 -0400
  Re: Where am I? Stanimir Stamenkov <s7an10@netscape.net> - 2011-10-13 03:23 +0300
    Re: Where am I? Arved Sandstrom <asandstrom3minus1@eastlink.ca> - 2011-10-13 07:16 -0300
      Re: Where am I? Arne Vajhøj <arne@vajhoej.dk> - 2011-10-13 22:51 -0400
        Re: Where am I? Patricia Shanahan <pats@acm.org> - 2011-10-14 04:27 +0100
          Re: Where am I? Arved Sandstrom <asandstrom3minus1@eastlink.ca> - 2011-10-14 07:26 -0300
            Re: Where am I? Arne Vajhøj <arne@vajhoej.dk> - 2011-10-14 18:17 -0400
    Re: Where am I? Roedy Green <see_website@mindprod.com.invalid> - 2011-10-13 10:51 -0700
  Re: Where am I? Ian Shef <invalid@avoiding.spam> - 2011-10-13 00:39 +0000
  Re: Where am I? markspace <-@.> - 2011-10-12 18:00 -0700

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