@@ -94,21 +94,11 @@ When a savepoint is manually triggered, it may be in process concurrently with a
## Tuning Network Buffers
The number of network buffers is a parameter that can currently have an effect on checkpointing at large scale.
The Flink community is working on eliminating that parameter in the next versions of Flink.
The number of network buffers defines how much data a TaskManager can hold in-flight before back-pressure kicks in.
A very high number of network buffers means that a lot of data may be in the stream network channels when a checkpoint
is started. Because the checkpoint barriers travel with that data (see [description of how checkpointing works](../internals/stream_checkpointing.html)),
a lot of in-flight data means that the barriers have to wait for that data to be transported/processed before arriving
at the target operator.
Having a lot of data in-flight also does not speed up the data processing as a whole. It only means that data is picked up faster
from the data source (log, files, message queue) and buffered longer in Flink. Having fewer network buffers means that
data is picked up from the source more immediately before it is actually being processed, which is generally desirable.
The number of network buffers should hence not be set arbitrarily large, but to a low multiple (such as 2x) of the
minimum number of required buffers.
Before Flink 1.3, an increased number of network buffers also caused increased checkpointing times since
keeping more in-flight data meant that checkpoint barriers got delayed. Since Flink 1.3, the
number of network buffers used per outgoing/incoming channel is limited and thus network buffers
may be configured without affecting checkpoint times
(see [network buffer configuration](../setup/config.html#configuring-the-network-buffers)).
## Make state checkpointing Asynchronous where possible