Just noticed this strange code committed in revision 7669 to fix the producer window size issue https://jira.jboss.org/jira/browse/JBMESSAGING-1693
public synchronized void confirm(final Packet packet) { if (packet.getType() == PacketImpl.SESS_ACKNOWLEDGE || packet.getType() == PacketImpl.CREATESESSION || packet.getType() == PacketImpl.SESS_CREATECONSUMER || packet.getType() == PacketImpl.SESS_START || packet.getType() == PacketImpl.PING || packet.getType() == PacketImpl.SESS_FLOWTOKEN) { if (resendCache != null && packet.isRequiresConfirmations()) { lastReceivedCommandID++; receivedBytes += packet.getPacketSize(); if (receivedBytes >= confWindowSize) { receivedBytes = 0; if (connection.isActive()) { final Packet confirmed = new PacketsConfirmedMessage(lastReceivedCommandID); confirmed.setChannelID(id); doWrite(confirmed); } } } } else { if (resendCache != null && packet.isRequiresConfirmations()) { lastReceivedCommandID++; receivedBytes += packet.getPacketSize(); if (receivedBytes >= confWindowSize) { receivedBytes = 0; if (connection.isActive()) { final Packet confirmed = new PacketsConfirmedMessage(lastReceivedCommandID); confirmed.setChannelID(id); doWrite(confirmed); } } } } }