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From 煜 韦 <yu20...@hotmail.com>
Subject RE: Question about log files
Date Fri, 10 Apr 2015 06:34:13 GMT
Is that possible to use similar operations as "w+" to write logs? So if log file is deleted
by mistake or on purpose, it could be re-created if some content need to be written.


From: jrottinghuis@gmail.com
Subject: Re: Question about log files
Date: Mon, 6 Apr 2015 10:39:52 -0700
To: user@hadoop.apache.org

This depends on your OS.When you "delete" a file on Linux, you merely unlink the entry from
the directory.The file does not actually get deleted until until the last reference (open
handle) goes away. Note that this could lead to an interesting way to fill up a disk.You should
be able to see the open files by a process using the lsof command.The process itself does
not know that a dentry has been removed, so there is nothing that log4j or the Hadoop code
can do about it.Assuming you have some rolling file appender configured, log4j should start
logging to a new file at some point, or you have to bounce you daemon process.

Sent from my iPhone
On Apr 6, 2015, at 6:19 AM, Fabio C. <anytek88@gmail.com> wrote:

I noticed that too, I think Hadoop keeps the file open all the time and when you delete it
it is just no more able to write on it and doesn't try to recreate it. Not sure if it's a
Log4j problem or an Hadoop one...
yanghaogn, which is the *correct* way to delete the Hadoop logs? I didn't find anything better
than deleting the file and restarting the service...

On Mon, Apr 6, 2015 at 9:27 AM, 杨浩 <yanghaogn@gmail.com> wrote:
I think the log information has lost.
 the hadoop is not designed for that you deleted these files incorrectly
2015-04-02 11:45 GMT+08:00 煜 韦 <yu2003w@hotmail.com>:

Hi there,
If log files are deleted without restarting service, it seems that the logs is to be lost
for later operation. For example, on namenode, datanode.
Why not log files could be re-created when deleted by mistake or on purpose during cluster
is running?


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