Re: Jasper 2 Synchronized JSP compiles

[Remy Maucherat]

Glenn Nielsen wrote:

I have some ideas on how invoking the javac compiler for compiling JSP 
pages can be
improved.  Currently Jasper 2 uses ant to do compiles from within Tomcat 
which are
synchronized.

There are currently several problems.

1. The known javac memory leak.

2. JSP page compiles are synchronized.

3. Jikes currently can't be configured for windows because the windows 
build of
   jikes doesn't support -encoding.

4. We may be getting some bug reports related to this problem noted in 
the Ant
   documentation for the javac task:

Windows Note:When the modern compiler is used in unforked mode on 
Windows, it locks up the files present in the classpath of the  
task, and does not release them. The side effect of this is that you 
will not be able to delete or move those files later on in the build. 
The workaround is to fork when invoking the compiler.

Recommendation:

Change Jasper 2 so that it tells ant to fork the javac compile.  This 
should remove the need
to synchronize the compiles.  It will also move java compilation outside 
of the JVM process
Tomcat is running in saving JVM heap memory and reducing GC overhead 
from objects created for
JSP compiles.  This could be done by just adding another parameter 
called "fork" to the
JspServlet paramters. If fork=true ant forks the javac compile and no 
synchronization is done.
The default for fork would be false.


+1. The compilation is not completely thread safe for concurrent 
requests on the same JSP, BTW (and it's quite complex to make it thread 
safe - I tried).

Remy


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Re: Jasper 2 Synchronized JSP compiles

[Kin-Man Chung]

Performance-wise, wouldn't doing javac compilation in another process
be much worse than synchronized javac, at least for systems with small
number of processors?  It would nice if we can have some numbers for
comparision.

I know javac used to have memory leak, but is it still true for modern
compilers, such as the one in JDK 1.4.0?

BTW, I am +1 on the proposal.

> Date: Wed, 04 Dec 2002 09:04:35 -0600
> From: Glenn Nielsen <[EMAIL PROTECTED]>
> Subject: Jasper 2 Synchronized JSP compiles
> To: [EMAIL PROTECTED]
> 
> I have some ideas on how invoking the javac compiler for compiling JSP pages 
can be
> improved.  Currently Jasper 2 uses ant to do compiles from within Tomcat which 
are
> synchronized.
> 
> There are currently several problems.
> 
> 1. The known javac memory leak.
> 
> 2. JSP page compiles are synchronized.
> 
> 3. Jikes currently can't be configured for windows because the windows build 
of
> jikes doesn't support -encoding.
> 
> 4. We may be getting some bug reports related to this problem noted in the Ant
> documentation for the javac task:
> 
> Windows Note:When the modern compiler is used in unforked mode on Windows, it 
locks up the files present in the 
> classpath of the  task, and does not release them. The side effect of 
this is that you will not be able to delete 
> or move those files later on in the build. The workaround is to fork when 
invoking the compiler.
> 
> Recommendation:
> 
> Change Jasper 2 so that it tells ant to fork the javac compile.  This should 
remove the need
> to synchronize the compiles.  It will also move java compilation outside of 
the JVM process
> Tomcat is running in saving JVM heap memory and reducing GC overhead from 
objects created for
> JSP compiles.  This could be done by just adding another parameter called 
"fork" to the
> JspServlet paramters. If fork=true ant forks the javac compile and no 
synchronization is done.
> The default for fork would be false.
> 
> Comments?
> 
> Regards,
> 
> Glenn
> 
> 
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> To unsubscribe, e-mail:   
> For additional commands, e-mail: 
> 


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Re: Jasper 2 Synchronized JSP compiles

[Costin Manolache]

+1, good idea !

Costin

Glenn Nielsen wrote:

> I have some ideas on how invoking the javac compiler for compiling JSP
> pages can be
> improved.  Currently Jasper 2 uses ant to do compiles from within Tomcat
> which are synchronized.
> 
> There are currently several problems.
> 
> 1. The known javac memory leak.
> 
> 2. JSP page compiles are synchronized.
> 
> 3. Jikes currently can't be configured for windows because the windows
> build of
> jikes doesn't support -encoding.
> 
> 4. We may be getting some bug reports related to this problem noted in the
> Ant
> documentation for the javac task:
> 
> Windows Note:When the modern compiler is used in unforked mode on Windows,
> it locks up the files present in the classpath of the  task, and
> does not release them. The side effect of this is that you will not be
> able to delete or move those files later on in the build. The workaround
> is to fork when invoking the compiler.
> 
> Recommendation:
> 
> Change Jasper 2 so that it tells ant to fork the javac compile.  This
> should remove the need
> to synchronize the compiles.  It will also move java compilation outside
> of the JVM process Tomcat is running in saving JVM heap memory and
> reducing GC overhead from objects created for
> JSP compiles.  This could be done by just adding another parameter called
> "fork" to the JspServlet paramters. If fork=true ant forks the javac
> compile and no synchronization is done. The default for fork would be
> false.
> 
> Comments?
> 
> Regards,
> 
> Glenn




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