I have a application which uses .net Thread-pool to have multiple threads.It uses log4net for write logs to a plain text file. Is it a good idea to use log4net for asynchronous logging like this. Or do i need to have separate MSMQ implementation to append messages?
You can use log4net as-is for file-based logging for multi-threaded applications. The log messages from all the threads will be written to the same file. It can get a little confusing to read all the interspersed messages, but it's better than not having logging. You'll definitely want to log the thread ID in the appender format so you can tell which messages are coming from which thread.
There are probably more fancy things you can do to handle the logging for different threads, but I've never really had to go down that road. I prefer to stick with file-based logging, and having all the threads log to one file is easier to deal with than having each thread log to its own file, in my opinion.
Related
I can't find information whether log4net is a MOM. If not then why? I tried to figure it out from their website.
log4net is not a message oriented middleware.
A MOM supports the exchange of general-purpose messages in a distributed application environment. Data is exchanged by message passing and/or message queuing supporting both synchronous and asynchronous interactions between distributed computing processes.
A MOM is usually designed for these goals:
Asynchronicity
Extensibility
Load Balancing
Why is log4net not a message oriented middleware?
Because log4net was designed with these goals in mind:
Speed of logging (or not logging, when disabling log)
Flexibility of logging (can output to multiple logging targets and easily modify writing strategy at runtime)
Being able to output to multiple targets (including remote via UDP) is a crucial feature of a MOM. However log4net does not create a communication layer between applications, it only enables logs to be written to multiple targets. It also does not support asynchronous logging out of the box. So it does not offer everything a MOM is expected to.
I'm trying to evaluate the reasons to use a logging system like Winston in node.js vs just writing my own logging method. It seems like logging libraries don't really offer much.
Some logging systems (like log4j) have logging hierarchies where if you log to a.b.c it logs to a.b and a as well (unless you have other complicated stop-propogation configurations). Is this kind of stuff usually overkill? What situation would you need that for?
I'm considering just writing a logging function that writes logs to a mongo database, which I'll then be able to pretty easily query and search through. Presumably a logging library can do that, but it seems like it would be just as much work to use a library for that as to write it from scratch.
So in short: what are the benefits to using a logging system?
I don't know about log4j, and not too much about Winston; haven't used it for more than 3 minutes.
But here are the few advantages I'd like to see in a logging system:
Error levels
I must be able to specify the log level I'd like to write to. It's good to have some defaults also (warning, error, debug, etc).
Streaming
You are able to do everything you want when something gets logged: Write it to a file, write it to the database, etc. It's up to you.
Customization
I'd like to be able to:
Timestamped messages
Colored messages when writing to process.stdout (super important while developing!)
Possibility of prefixing the message with the level (for files), or with anything else (when launching various loggers within the same process). This is useful for differentiating between various levels/logger instances that write to the same stream.
I want to use a logging framework like log4cxx in a multi-threaded application.
If the output of the log will be to a file, correct serialization of the messages is needed.
I was asking myself how (and if) these frameworks get correct serialization of the output without using some sort of synchronization object.
I guess that if it is using synchronization objects (for example to access a queue to log messages), this could cause changes in the behaviour of the involved threads, so also changing the behaviour (and bugs...) of the whole logged application.
log4cxx is indeed synchronized, like the other log4XXX frameworks. The synchronization is done in the appenders and is necessary to guarantee that content of log entries are not mixed together. This does not change the behavior of your threads, but the threads do encounter a small performance hit. The performance hit is small compared to the performance hit of I/O when logging to a file.
If you are still worried about performance you can consider using asynchronous logging (using the AsyncAppender that handles logging in a separate thread. Using the async approach you cannot be guaranteed that messages are logged (e.g. if the application crashes before the logging thread handles the message). The most simple way to improve performance is to reduce the amount of logging.
I am using log4net for logging calls to an API. Many calls. The methods I am calling have multiple megabytes of data for request/response pairs, and it is very hard to read logs that have multiple calls written to the same file, no matter what logging pattern I use. So, I feel the best approach is to log to multiple files.
I am having a hard time figuring out how to get log4net to do this, or if it even supports it.
From the Log4Net FAQ - Can the outputs of multiple client request go to different log files?
Many developers are confronted with the problem of distinguishing the log output originating from the same class but different client requests. They come up with ingenious mechanisms to fan out the log output to different files. In most cases, this is not the right approach.
It is simpler to use a context property or stack (ThreadContext) ... Thereafter, log output will automatically include the context data so that you can distinguish logs from different client requests even if they are output to the same file.
I looked at the documentation on Contexts and Context Properties. It seemed Event Context fit best, but I tried reading docs for other Contexts too. It seems they just allow me to put additional properties that end up in my log files, rather than being a component of a log file name, or allow me to automatically append to different files.
Is there a way to configure appenders to create different files for different context properties or context stack levels, etc?
Edit:
I am using log4net via Castle Windsor Logging facility, and I'm considering switching to NLog to solve this problem.
NLog seems to support this behavior by using the {logger} layout renderer in the File target's fileName property. I can effectively set this property by making a child logger with Windsor's ILogger.CreateChildLogger method, and setting {logger.shortName=True}.
See:
http://nlog-project.org/forum#nabble-td1685989
I'd still prefer to use log4net if possible, since the project I am testing uses it. Maybe my NLog example can give someone inspiration on how this could be done on log4net, and maybe they can help me figure it out :)
This article may be of interest to you: Log4Net: Programmatically specify multiple loggers (with multiple file appenders)
Also if you are only worried about readability there may be log file viewers that can seperate out log entries by thread name.
Another possibility you have is to log the entries in a database including your thread name and these entries are easily filtered using sql.
I'm wondering if anyone has any experience using log4net in a multi-threaded environment like asp.net. We are currently using log4net and I want to make sure we won't run into any issues.
We run log4net (and log4cxx) in highly multi-threaded environments without issue. You will want to be careful how you configure them though.
The issue with log4net that Jeff describes pertains to the use of a certain appender. We stick with simple log file appenders on the whole to reduce the impact of logging on the operation of the code. Writing a line to a file is pretty minimal, kicking off another database transaction is very heavy.