Gregory Shimansky wrote:
Hello Paulex
I have a question about this problem. Do you know how exception in
finalizer
method affects the finalizer thread that it becomes suspended? I thought
that when calling finalize method the code should catch all exceptions
thrown by it and ignore them. AFAIK that's how finalizers are
implemented in
DRLVM. It specification it is written that
"If an uncaught exception is thrown by the finalize method, the
exception is
ignored and finalization of that object terminates."
Hi Gregory,
I'll let Paulex speak for himself but just thought I'd mention that the
NPE does not occur when the test case in the JIRA is run against a RI. I
appreciate what you are saying about finalizers but IMHO it is also good
to bring our behaviour (even in an "edge case" like this) into line with
the RI.
Best regards,
George
2006/5/19, Paulex Yang (JIRA) <[EMAIL PROTECTED]>:
java.io.FileInputStream and FileOutputStream might cause Finalizer
thread
suspending
------------------------------------------------------------------------------------
Key: HARMONY-479
URL: http://issues.apache.org/jira/browse/HARMONY-479
Project: Harmony
Type: Bug
Components: Classlib
Reporter: Paulex Yang
If one FileInputStream instance is not constructed properly, say, the
given file doesn't exist, the constructor will throw exception but the
FileInputStream instance is still necessary to be garbage collected,
and the
spec of FileInputStream's finalize() method requires that close()
must be
invoked, but the current implementation of FileInputStream.close()(as
below) will causes NullPointerException in Finalizer thread because
channel
field has not been initialized yet.
public void close() throws IOException {
synchronized (channel) {
synchronized (this) {
if (channel.isOpen() && fd.descriptor >= 0) {
channel.close();
}
fd.descriptor = -1;
}
}
}
This issue applies to FileOutputStream, too. Test case below can
reproduce
this issue only in debugger, because it is not easy to get the handle of
Finalizer thread. Debugging the test case to the statement following the
System.gc(), the debugger will show that the Finalizer thread is
suspended
due to NullPointerException.
public class FileInputStreamTest {
public static void main(String[] args) throws Exception{
FileInputStream is = null;
try{
is = new FileInputStream(new File("nonexist"));
}catch(Exception e){
System.gc();
e.printStackTrace();
}
}
}
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