java - DatagramChannel.receive() seems to buffer packets -

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i have server sending udp packets of 40 bytes every ~50 milliseconds client. client receives these packets of time. however, every ~1-3 seconds no packets arrive ~500ms , following packets after arrive @ 0ms delay, if packets buffered.

the following code called in separate thread sole purpose of receiving packets: 

public synchronized int readudp(datagramchannel channel) throws ioexception {     inetsocketaddress sourceaddress = (inetsocketaddress) channel.receive(in);     bytesread = in.position();     in.flip();      // read data out of buffer... }

here notes on debugging findings:

  • the server runs on same computer client, communication 1 way (server -> client). traffic goes 127.0.0.1 127.0.0.1 , therefore there no network interference.
  • using rawcap have taken @ packets , times , no oddities visible, delta times between packets in capture ~50ms.
  • the datagramchannel in blocking mode.
  • the client connected server tcp simultaneously, no packets actively sent on channel.
  • the buffer in packets stored bytebuffer capacity of 1024 bytes.
  • the position of buffer before calling channel.receive(in) 0.
  • the position of buffer after calling channel.receive(in) 40.
  • the time after packet being read , arriving @ same code section again ~0ms. therefore, can conclude channel.receive(in) takes ~500ms sometimes.
  • the function readudp called 1 place.

a typical glitch looks this: 

time: 49 time: 51 time: 49 time: 51 time: 307 time: 0 time: 0 time: 0 time: 0 time: 1 time: 41 time: 51 time: 49

i appreciate if examine fresh pair of eyes. other close case find here: http://www.coderanch.com/t/476539/android/mobile/udp-datagramsocket-receive-glitches. code not interact android in way should note though.


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