Github user selvaganesang commented on a diff in the pull request:
https://github.com/apache/incubator-trafodion/pull/1209#discussion_r136582435
--- Diff:
dcs/src/main/java/org/trafodion/dcs/master/listener/ListenerWorker.java ---
@@ -86,39 +86,43 @@ public void run() {
DataEvent dataEvent;
while(true) {
- // Wait for data to become available
- synchronized(queue) {
- while(queue.isEmpty()) {
- try {
- queue.wait();
- } catch (InterruptedException e) {
+ try {
+ // Wait for data to become available
+ synchronized(queue) {
+ while(queue.isEmpty()) {
+ try {
+ queue.wait();
+ } catch (InterruptedException e) {
+ }
}
+ dataEvent = queue.remove(0);
}
- dataEvent = queue.remove(0);
- }
- SelectionKey key = dataEvent.key;
- SocketChannel client = (SocketChannel) key.channel();
- Socket s = client.socket();
- ClientData clientData = (ClientData) key.attachment();
- ListenerService server = dataEvent.server;
- dataEvent.key = null;
- dataEvent.server = null;
-
- switch (clientData.hdr.getOperationId()){
- case ListenerConstants.DCS_MASTER_GETSRVRAVAILABLE:
- clientData =
requestGetObjectRef.processRequest(clientData, s);
- break;
- case ListenerConstants.DCS_MASTER_CANCELQUERY:
- clientData =
requestCancelQuery.processRequest(clientData, s);
- break;
- default:
- clientData = requestUnknown.processRequest(clientData,
s);
- break;
+ SelectionKey key = dataEvent.key;
+ SocketChannel client = (SocketChannel) key.channel();
+ Socket s = client.socket();
+ ClientData clientData = (ClientData) key.attachment();
+ ListenerService server = dataEvent.server;
+ dataEvent.key = null;
+ dataEvent.server = null;
+
+ switch (clientData.hdr.getOperationId()){
+ case ListenerConstants.DCS_MASTER_GETSRVRAVAILABLE:
+ clientData =
requestGetObjectRef.processRequest(clientData, s);
+ break;
+ case ListenerConstants.DCS_MASTER_CANCELQUERY:
+ clientData =
requestCancelQuery.processRequest(clientData, s);
+ break;
+ default:
+ clientData =
requestUnknown.processRequest(clientData, s);
+ break;
+ }
+ // Return to sender
+ int requestReply = clientData.requestReply;
+ key.attach(clientData);
+ server.send(new PendingRequest(key, requestReply));
+ } catch (Exception e){
+ LOG.error("Unexpected Exception", e);
--- End diff --
So, you want to do something like the program below that prints 100 times
null pointer exception instead of exiting the process.
public class TestS
{
public static void main(String args[])
{
for (int i = 0; i < 100; i++)
{
String s = null;
try
{
System.out.println ("Length of the string " + s.length());
} catch (Exception e) {
e.printStackTrace();
}
}
}
}
But serious errors like OutOfMemoryError will anyway won't be caught by
this handler. So, do you think it is ok for DCSMaster to hang then.
My earlier comment is to ensure that all unchecked exceptions (Runtime
Exceptions or any exception that need not be caught or thrown) should also be
treated like critical error as above. I would say if you want DCS Master not
to hang at all conditions, then it can't be done by handling exceptions.
If you attempt to avoid this hang by handling Throwable like catch
(Throwable t), then it very bad because the only way to recover from this
situation is to kill the process manually, which would have happened
automatically if you didn't handle Throwable.
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