[FOP-765] Minor problem in sample code for embedding

• Type: Bug
• Status: Open
• Resolution: Unresolved
• Affects Version/s: 2.5
• Component/s: documentation
• Environment: Operating System: other; Platform: Other
• External issue ID: 24378
• Assignee: Unassigned
• Reporter: Manuel Mall
• Created: 04/Nov/03 09:11
• Updated: 18/Dec/12 17:00

Description

The sample code on the FOP web site for embedding uses in a number of places
constructs like

Driver driver = new Driver(new InputSource(args[0]),
new FileOutputStream(args[1]));

or

driver.setOutputStream(new FileOutputStream(args[1]));

Using "new ...Stream(...)" as a constructor or function argument is dangerous
as the stream doesn't get closed until the object is garbage collected. This
can lead to "out of file handle" conditions.

I learned this the hard way with a (supposedly) perfectly working server
application which had fop embedded. The app ran happily for over two years.
Then a hardware upgrade came along and the system admin changed the Java VM
settings to give it more memory as the new machine had lots of it. Suddenly the
system was running out of file handles because the Java VM did less garbage
collection which in turn kept all those implicitly constructed streams open.

The sample code should probably be looking more like

FileOutputStream fos = new FileOutputStream(args[1]);
Driver driver = new Driver(new InputSource(args[0]), fos);
fos.close();

or to make sure the file is always closed like:

FileOutputStream fos = null;
try {
fos = new FileOutputStream(args[1]);
Driver driver = new Driver(new InputSource(args[0]), fos);
fos.close();
} finally {
if (fos != null) {
try

{ fos.close(); }

catch (IOException ioe) {}
}
}

which is probably an overkill for the sake of the example.