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http://issues.apache.org/jira/browse/DERBY-1466?page=comments#action_12420949 ]
Sunitha Kambhampati commented on DERBY-1466:
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I took a quick look at this and want to start a discussion on how this could
be solved.
Per java api for PrintWriter
-- There is no method to turn autoflush on an existing PrintWriter object.
-- when autoflush is on, flush will happen on the println statement only.
some solution options:
1) one is wrap the user's writer object with a PrintWriter and set autoflush to
true
-- change in code only required in two places.
-- maybe ugly to wrap the object.
2) explicitly call flush in all places after we write to this writer object.
In Eclipse, searched for places where the logWriter in NetworkServerControl is
referenced, here is the list
NetworkServerControlImpl - org.apache.derby.impl.drda - java/drda - ks_trunk
consoleExceptionPrintTrace(Throwable) (3 potential matches)
consoleMessage(String) (3 potential matches)
executeWork(String[]) (potential match)
setLogWriter(PrintWriter) (potential match)
shutdown() (2 potential matches)
So that is not a lot of places. so option 2 should be simple too. unless we
miss to call flush in all the places.
------------------
There is one case where the writer is passed to exception.printStackTrace . If
this gets flushed correctly in autoflush mode, I think #1 seems ok to me, less
number of changes than #2.
I was concerned a bit if setting autoflush will have any performance impact.
But maybe it is ok since console output is not expected to be verbose anyways.
Comments/thoughts ?
Thanks.
> Network Server should flush the PrintWriter after console output
> ----------------------------------------------------------------
>
> Key: DERBY-1466
> URL: http://issues.apache.org/jira/browse/DERBY-1466
> Project: Derby
> Type: Improvement
> Components: Network Server
> Versions: 10.1.2.1
> Reporter: Kathey Marsden
>
> If Network Server is started with a PrintWriter specified for console output
> it will not automatically flush output such as starting the server. This
> can be confusing as the console output shows no activity.
> Users currently need to specify the PrintWriter to autoflush e.g.
> starterWriter = new PrintWriter(new FileOutputStream(new
> File(SERVER_START_LOG)),true);
> derbyServer = new NetworkServerControl();
> derbyServer.start(starterWriter);
> For repro see:
> http://www.nabble.com/Questions-about-Network-Server-API-Behavior-p5055814.html
> And change the following line in the program to not autoflush as follows:
> starterWriter = new PrintWriter(new FileOutputStream(new
> File(SERVER_START_LOG)),false);
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