Thank you very much!! I will try that!!
On 01/05/2015 01:01 AM, Nathan Leung wrote:
Out of the box storm does not allow you to determine which machine a
bolt or spout runs on. However, it's possible to write a custom
scheduler to do this (see
http://xumingming.sinaapp.com/885/twitter-storm-how-to-develop-a-pluggable-scheduler/
for a guide).
On Sun, Jan 4, 2015 at 11:51 PM, hjh <[email protected]
<mailto:[email protected]>> wrote:
Thank you very much for the explanation. I am new to storm so I
thought the whole topology runs like a message broker. So I design
the topology accordingly. By the way, in most cases, we can not
decide which bolt or spout runs in which machine or thread right?
Does that mean we have to take care of such situation carefully?
Thank you very much!!
On 01/04/2015 11:34 PM, Nathan Leung wrote:
Every time you send a tuple, it should be a new tuple. Secondly,
when you send a tuple within the same process, the data is passed
by reference, not serialized and deserialized. That means if you
use local cluster, or even a remote cluster you will see that
some of your data is sent by reference. So when you send a
static variable by reference and then change it, subsequent bolts
will see this change.
Note that in remote cluster, localOrShuffleGrouping will send if
at all possible within the same process, and thereby avoid
network / serialization / deserialization costs. ShuffleGrouping
will send in process as well if there are any downstream bolts in
the same process, because it uses round robin. FieldsGrouping is
the same if your key has reasonable distribution. It's possible
that you could avoid passing by reference when using none
grouping or direct grouping but I'm not really sure why you would
explicitly try to avoid this.
Also I would note that passing then changing a static variable
can be tricky; hopefully you have protected it against concurrent
modification from other bolt tasks within the same process.
On Sun, Jan 4, 2015 at 7:18 PM, hjh <[email protected]
<mailto:[email protected]>> wrote:
Hi, I am new to storm and I met a problem with tuple. In the
local mode does tuple between connected bolts share the same
object? For example BoltA emit a tuple to BoltB. If BoltB is
processing the tuple (this tuple is assigned to a private
variable, say VAR, in BoltB) and at the same time BoltA sends
another tuple to BoltB, then VAR changed immediately. Does
that mean in local mode BoltA and BoltB share the same tuple
instance?? And how to deal with such situation?
PS. I use java.
Any suggestion is warmly welcomed
Thank you very much!!!
