Hi,
Since Socket.receive blocks until a packet is received,
I do not see any advantage of the suggested code.
Best regards,
Frank
Vivi Zhang wrote:
Hi,
I am looking at ways to tuning my application with embedded SNMP agent
with SNMP4J and SNMP4J-Agent.
I have two questions about the implementation of inner class
ListernThread.
Q1) Line 315 * try {
socket.receive(packet);
}
catch (InterruptedIOException iiox) {
if (iiox.bytesTransferred <= 0) {
continue;
}*
If we see SocketTimeoutException since there is no packet to read, can
we put the thread to a small break before it goes for another
socket.receive() call? The suggestion is intended to ease some
pressure on the CPU and network resource. Do you see any potential
drawback from this change?
Q2) Line 307 *DatagramPacket packet = new DatagramPacket(buf, buf.length,
udpAddress.getInetAddress(),
udpAddress.getPort());**
*A DatagramPacket object is created repeatedly within the while
loop. What is the drawback if we move the stmt outiside while loop. The
logic behind this suggestion is avoiding object creating repeatedly
withing the loop.
Thanks.
Vivi
P.S.
I am using SNMP4J 1.9.3c.
Following is a section of code I cut from DefaultUdpTransportMapping.java.
============================================================================
while (!stop) {
* DatagramPacket packet = new DatagramPacket(buf, buf.length,
udpAddress.getInetAddress(),
udpAddress.getPort());*
try {
try {
socket.receive(packet);
}
catch (InterruptedIOException iiox) {
if (iiox.bytesTransferred <= 0) {
* continue;*
}
}
if (logger.isDebugEnabled()) {
logger.debug("Received message from "+packet.getAddress()+"/"+
packet.getPort()+
" with length "+packet.getLength()+": "+
new OctetString(packet.getData(), 0,
packet.getLength()).toHexString());
}
ByteBuffer bis;
// If messages are processed asynchronously (i.e. multi-threaded)
// then we have to copy the buffer's content here!
if (isAsyncMsgProcessingSupported()) {
byte[] bytes = new byte[packet.getLength()];
System.arraycopy(packet.getData(), 0, bytes, 0, bytes.length);
bis = ByteBuffer.wrap(bytes);
}
else {
bis = ByteBuffer.wrap(packet.getData());
}
fireProcessMessage(new UdpAddress(packet.getAddress(),
packet.getPort()), bis);
}
catch (SocketTimeoutException stex) {
// ignore
}
catch (PortUnreachableException purex) {
synchronized (DefaultUdpTransportMapping.this) {
listener = null;
}
logger.error(purex);
if (logger.isDebugEnabled()) {
purex.printStackTrace();
}
if (SNMP4JSettings.isFowardRuntimeExceptions()) {
throw new RuntimeException(purex);
}
break;
}
catch (SocketException soex) {
logger.error("Socket for transport mapping "+toString()+
" error: "+soex.getMessage(), soex);
stop = true;
}
catch (IOException iox) {
logger.warn(iox);
if (logger.isDebugEnabled()) {
iox.printStackTrace();
}
if (SNMP4JSettings.isFowardRuntimeExceptions()) {
throw new RuntimeException(iox);
}
}
}
synchronized (DefaultUdpTransportMapping.this) {
listener = null;
stop = true;
if (socket != null) {
socket.close();
}
}
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