Hi Shu, Apologies for dealy in response.
Close packet is something which is the last packet of the current block after writing which , the current block is closed and a new pipeline is setup for the next block. Your understanding of the one.isLastPacketInBlock() is correct. Regards, Manjunath On Wed, Dec 14, 2016 at 9:37 PM, wang shu <uchicagoshuw...@gmail.com> wrote: > Hi all, > > I have a question regarding the streamer thread (Line 382-575) > implementation at DFSOutputStream.java(http://gr > epcode.com/file/repo1.maven.org/maven2/org.apache.hadoop/had > oop-hdfs/2.7.1/org/apache/hadoop/hdfs/DFSOutputStream.java# > DFSOutputStream.DataStreamer.run%28%29). > > > What's the logic of line 468-485 and line 535-548, why it check the packet > is the last one twice and the comments are different, one is " > // wait for all data packets have been successfully acked" and another is > "// wait for the close packet has been acked". What's the close packet? > > My understanding of this is: > If a packet is not the last in block, then the packet is sent directly, > and no need to wait for ACK. > If a packet is the last one, then it will first wait for all previous > packet to be ACKed, and then it will send the last packet in this block( > called close packet, I guess?), and then will need wait the last packet to > be ACKed. > > Thanks a lot for your help. > > > Best, > > Shu >
