Re: Could this unclosed() byteArrayInputStream cause high Heap usage ?

From:
Krist <krislioe@gmail.com>
Newsgroups:
comp.lang.java.programmer
Date:
Fri, 5 Feb 2010 22:56:40 -0800 (PST)
Message-ID:
<65acf367-d77b-4481-b3c7-9d28766e1af8@s36g2000prf.googlegroups.com>
On 6 Feb, 13:33, Kevin McMurtrie <mcmurt...@pixelmemory.us> wrote:

In article
<65da124a-3abd-4d57-9660-3c25784ab...@p13g2000pre.googlegroups.com>,

 Krist <krisl...@gmail.com> wrote:

Hi all,

As part of our reporting integrated with our JSF/JSP application, the
report is converted to PDF then sent to browser for user to display.
mean while during peak load our Heap usage could reach 3.5GB - 4GB. So
I am suspecting the unclosed byteArrayInputStream is the cause.
(This is a production application so I am collecting information
before change the code)

Is the unclosed() byteArrayInputStream really cause the problem ?
(the codes is below)

Thank you,
Krist

ByteArrayInputStream byteArrayInputStream = (ByteArrayInputStream)

reportClientDoc.getPrintOutputController().export(exportOptions);
reportClientDoc.close();
writeToBrowser(byteArrayInputStream, response, "application/csv",
EXPORT_FILE);

private void writeToBrowser(ByteArrayInputStream byteArrayInputStream,
HttpServletResponse
response, String mimetype, String exportFile)
   throws Exception {
      byte[] buffer = new byte[byteArrayInputStream.available()=

];

      int bytesRead = 0;
      response.reset();
      response.setHeader("Content-disposition", "inline;filename=

=" +

exportFile);
      response.setContentType(mimetype);
      //Stream the byte array to the client.
      while((bytesRead = byteArrayInputStream.read(buffer)) !=

= -1)

            { response.getOutputStream().write(buffer , 0,
bytesRead);}

      //Flush and close the output stream.
      response.getOutputStream().flush();
      response.getOutputStream().close();
   }


This probably isn't where your memory is going. Turn on object
histogram dumps then send a QUIT signal when memory is high.

On the other hand, the code is bad:

Casting the InputStream to an implementation is prone to failure. Don'=

t.

  byte[] buffer = new byte[byteArrayInputStream.available()];

InputStream.available() returns a value between 0 and the entire size of
the data. It's for avoiding blocking I/O and aligning buffers. It's
not for setting up a constant buffer size. In the case of
ByteArrayInputStream, it's the entire size of the data. Another
implementation might return zero and then you'd infinite loop. Use a
constant, like 2048 for WAN or 65536 for LAN.

If the PrintOutputController belongs to you, consider modifying it to
write directly to an OutputStream. This will eliminate intermediate
buffering and provide a faster first-byte response. The downside is
that the PrintOutputController could be active and holding resources for
a very long time if the client is on dialup. Which is best depends on
the application.
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Hi sir,

When will the memory taken by the byteArrayInputStream will be
released ?
Will it be garbage collected ?

Thanks,
Krist

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