Github user clockfly commented on the pull request:
https://github.com/apache/storm/pull/268#issuecomment-73909944
@miguno,
I am sure you are aware that you can still send data to this channel even
if channel.isWritable return false.
check http://netty.io/4.0/api/io/netty/channel/Channel.html#isWritable()
boolean isWritable()
Returns true if and only if the I/O thread will perform the requested write
operation **immediately**. Any write requests made when this method returns
false are **queued** until the I/O thread is ready to process the queued write
requests.
doing or not doing isWritable check have nothing to do with message loss,
the isWritable check is purely used to optimize the performance for small
messages.
case1: If we have a large enough batch, then we will just flush to netty
internal queue. Netty will flush pending data in queueto wire when the wire is
not that busy.
case2: If we don't have a large enough batch, and the wire is busy, then
the Storm netty Client will wait for a while, buffer more messages in the
batch, and set a timer to flush later.
case3: If we don't have a large enough batch, and the wire is free, then
Storm Client will flush immediately, so that we have better latency.
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