Sorry but I fail to understand this example... Log event programmed? I didn't know I can program it... (without changing log4net source).
So far I know/see two cases where recursive logging can happen: 1. Something called from Appender.Append calls anu ILog logging methods 2. According to comment in https://issues.apache.org/jira/browse/LOG4NET-288 the bad configuration can also cause the recursion. I assume that's all that can cause recursions... As I plan to save logs from another thread I have to pay special attention to item 1. as any logging from database save procedure would cause the same logging to be executed again (tested). Without recursion but still flooding log system with endless messages. But what about IFilter.Decide? Should I assume it is not threadsafe? Gert On 4 March 2015 at 16:51, Dominik Psenner <dpsen...@gmail.com> wrote: > A log event might be badly programmed and recursive by definition. Think > of two objects that try each to log while trying to format each other: > > > > A { > > DoWork() { > > Log(“A: {0}”, B) > > } > > } > > B { > > DoWork () { > > Log(“B: {0}”, A) > > } > > } > > > > I might be wrong, but something like that does the recursive guard detect > and resolve. > > > > For the other question you’ll have to accept my apologies because I can’t > answer the question „how to write code“. J > > > > *Von:* Gert Kello [mailto:gert.ke...@gmail.com] > *Gesendet:* Mittwoch, 04. März 2015 15:16 > *An:* Log4NET User > *Betreff:* Re: AppenderSkeletion lock in DoAppend > > > > But what about this m_recursiveGuard? Is the recursion protection needed? > Perhaps it is, if log saving code logs something by itself? (Like warning > that database operation takes longer than expected)? > > Well, as I plan to make the database saving asyn I need to tackle this > problem anyway... I think I would like to log the performance problem. But > not when the problem occurs during saving log about the same performance > problem. Is there any guideline how to write such code? Something like > using OnlyOnceErrorHandler or is there anything similar for warnings? > > > > Gert > > > > On 4 March 2015 at 15:38, Dominik Psenner <dpsen...@gmail.com> wrote: > > Hi, > > > > from what I can recall it could happen that the formatted representation > of a logging event gets mixed up with data from other events and thus the > characters streamed to a sink become garbage (i.e. a file, console, ..) if > this lock is removed. > > > > Internally a lot of things are cached to improve performance and these > caches actually require proper locking. > > > > But my memory might be wrong, so feel free to remove the lock and let > several threads log events to your appender to see if it can handle it > properly. J > > > > Cheers > > > > *Von:* Gert Kello [mailto:gert.ke...@gmail.com] > *Gesendet:* Mittwoch, 04. März 2015 09:28 > *An:* log4net-user@logging.apache.org > *Bet**reff:* AppenderSkeletion lock in DoAppend > > > > Hi. > > I'm trying to create a database appender which high throughput... I looked > at code in AppenderSekeletion.DoAppend() method and saw following comment: > > public void DoAppend(LoggingEvent loggingEvent) > { > // This lock is absolutely critical for correct formatting > // of the message in a multi-threaded environment. Without > // this, the message may be broken up into elements from > // multiple thread contexts (like get the wrong thread ID). > > lock (this) > { > > I would like to remove this lock from my code but there's a couple of > issues I do not understand: > > 1. As I do not know the internals of log4net well enough I do not > understand why lock is important for message formatting? Is it because the > Layout.Format is not supposed to be thread safe? Or is it because the same > instance of m_renderWriter could be used by multiple threads (well, usage > of m_renderWriter is protected by another lock, added later. But AFAIK the > RenderLoggingEvent(LoggingEvent loggingEvent) is still not 100% thread safe) > > 2. The comment does not mention that lock is crucial for m_recursiveGuard > to work correctly. That's my main complaint: I almost overlooked the issue > of potentially skipped logging events. > > 3. What about implementations of IFilter.Decide? Are those (supposed to > be) thread safe? > > Gert > > >
