[asm] Re: Re: Re: Re: Question for using ASM to log the method invocation trace.

[Paul Keeble <csuml@xxxxxxxxxxx>]

Tomcat used to (might still) kill shutdown hooks if they took too long. Emma was one such user of shutdown hooks that suffered badly as it didn't get time to write out its coverage data before the thread was killed. I had to use Grobo with continuous writing instead to get complete coverage picture.

So you don't want to spend a long time in the shutdown hook, but a couple of seconds of work is not unreasonable. Any more than a few seconds and you might want another mechanism (continuous writing with a small buffer that is cleared by the shutdown hook).

PK

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From: Scott Vachalek <svachalek@xxxxxxxxx>
To: Sai Zhang <szhang@xxxxxxxxxxxxxxxxx>
Cc: Paul Keeble <csuml@xxxxxxxxxxx>; Zhongxian Gu <zgu@xxxxxxxxxxx>; asm@xxxxxxx
Sent: Thu, 22 July, 2010 23:09:11
Subject: [asm] Re: Re: Re: Question for using ASM to log the method invocation trace.

You can put anything into a shutdown hook but it's not really designed for doing much more than closing resources etc.  I imagine if you take too long, you risk having things like the garbage collector go away before you are done.  It's also not a very user-friendly model, to suddenly start doing a lot of work when the user is trying to quit the application.

On Thu, Jul 22, 2010 at 1:14 PM, Sai Zhang <szhang@xxxxxxxxxxxxxxxxx> wrote:

Hi all:

Setting up a shutdown hook for "cleaning" the instrumentation tasks seems to be a good practice. However, I am
wondering could I insert "any" code to the code block of the shutdown hook ?

that is:

Runtime.getRuntime().addShutdownHook(new Thread() {

  public void run() {

    
       //Could i insert arbitrary code here as normal Java programs?   
      //Could I do some sophisticated post-execution program analysis tasks here without producing a trace file?

}});


It seems that the shutdown hook may have some "side-effect". I have a fairly complex procedure m() which
throws no exception when calling directly from main. However, it behaves strangely when putting into the hook code block.

I am just guessing is there any special side-effects here?

thanks. Any comments are highly appreciated.

-
Sai

On Wed, Jun 30, 2010 at 3:13 AM, Paul Keeble <csuml@xxxxxxxxxxx> wrote:

Say you have a class:

class Tracer {

public static void trace(String )

public static void close()

}

Then you can happily insert the calls to Tracer.trace for the instrumenting. You can also right at the beginning of the program (before you instrument anything and when you set-up the FileWriter to begin with) set-up a shutdown hook using something like:

Runtime.getRuntime().addShutdownHook(new Thread() {

  public void run() {

    Tracer.close();

}});

Its not a concern of the tracing to get the file stream closed, it is for the shutdown of the program.

PK

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From: Zhongxian Gu <zgu@xxxxxxxxxxx>
To: asm@xxxxxxx
Sent: Wed, 30 June, 2010 5:10:33
Subject: [asm] Question for using ASM to log the method invocation trace.

Hi all,

I wish to use ASM to instrument the code and during the run, record the method invocation trace. I use AdviceAdapter to do that. To enhance the performance,
I use BufferedWriter to print info to the log file. The problem is that I don't know how to instrument the code to close the BufferedWriter. I must call it until all the
methods called which is only known at run-time. Without calling close method will cause information missing in the buffer.

I wonder if some of you have also experienced this condition and could you give me some hints. Thanks

Best

Zhongxian

--
Zhongxian Gu
http://wwwcsif.cs.ucdavis.edu/~gu/
Ph.D. Student in Computer Science, UC Davis
2249 Kemper Hall

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