Hi tao,
As a whole, `networkBufBytes` is not part of the heap. In fact, it is
allocated from the direct memory. The rough relationship (ignores min/max and
assumes managed memory is allocated on heap) between the variables are:
Total memory of TM (configured by taskmanager.heap.mb, the name
may be a little misleading) = heap memory (-XmX) + networkBufBytes.
networkBufBytes = Total memory of TM * networkBufFraction.
Therefore, the networkBufBytes = xmx / (1 - networkBufFraction) *
networkBufFraction.
Best,
Yun
------------------------------------------------------------------
From:徐涛 <happydexu...@gmail.com>
Send Time:2019 Jun. 13 (Thu.) 10:23
To:user <user@flink.apache.org>
Subject:Source code question - about the logic of calculating network buffer
Hi Experts,
I am debugging the WordCount Flink streaming program in local mode. Flink
version is 1.7.2
I saw the following calculation logic about network buffer in class
TaskManagerServices.
jvmHeapNoNet is equal to -xmx amount in Java.
why the networkBufBytes = xmx / (1-networkBufFraction) * networkBufFraction,
it is a bit strange.
why it is not calculated by xmx * networkBufFraction?
final long networkBufBytes = Math.min(networkBufMax, Math.max(networkBufMin,
(long) (jvmHeapNoNet / (1.0 - networkBufFraction) * networkBufFraction)));
Best
Henry
