[jira] [Updated] (STORM-738) Multilang needs Overflow-Control mechanism and HeartBeat timeout problem

["Rick Kellogg (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/STORM-738?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Rick Kellogg updated STORM-738:
-------------------------------
    Component/s: storm-multilang

> Multilang needs Overflow-Control mechanism and HeartBeat timeout problem
> ------------------------------------------------------------------------
>
>                 Key: STORM-738
>                 URL: https://issues.apache.org/jira/browse/STORM-738
>             Project: Apache Storm
>          Issue Type: Bug
>          Components: storm-multilang
>    Affects Versions: 0.10.0, 0.9.3-rc2, 0.9.4, 0.11.0
>            Reporter: DashengJu
>            Priority: Critical
>         Attachments: storm_multilang.png
>
>
> hi, all
> we have a topology, which have 3 components(spout->parser->saver) and the parser is Multilang bolt with python. We do not use ACK mechanism.
> we found 2 problems with Mutilang python script.
> 1) the parser python scripts may hold too many tuples and consume too many memory;
> 2) with MultiLang heartbeat mechanism described by  https://issues.apache.org/jira/browse/STORM-513, the python script always timeout to heartbeat, even when the parser bolt is normal, cause supervisor to restart itself.
> !storm_multilang.png!
> ShellBolt process === Father-Process
> PythonScript process === Child-Process
> The reason is :
> 1) when topology do not use ACK mechanism, the spout do not have Overflow-control ability, if the stream have too many tuples comes,  spout will send all the tuples to parser's ShellBolt process(Father-Process);
> 2) parser's ShellBolt process just put the tuples to _pendingWrites queue, if the _pendingWrites queue does not have limit;
> 3) parser's PythonScript process(Child-Process) call readMsg() to read a tuple from STDIN, handle the tuple, and emit a new tuple to its father process through STDOUT, and then call readTaskIds() from STDIN.  Because Father-Process's queue already have too many other tuples, Child-Process will read all the tuples to pending_commands, util received TaskIds.
> 4) so Child-Process process's pending_commands may contains too many tuples and consume too many memory.
> As to heartbeat, because there are too many pending_commands need Child-Process to handle, and Child-Process's every emit operation will need more I/O read operations from STDIN. It may need 10 seconds to handle one tuple, and this will cause the heartbeat tuple not handle quickly, and timeout will happen.
> Even if Father-Process's _pendingWrites have limits, for example 1000, Child-Process may needs 1000 x 1000 read operations then it can handle the heartbeat tuple.
> [~revans2] [~kabhwan] this related to Multilang and heartbeat, please help to confirm the two problems.
> I think Father-Process and Child-Process need Overflow-Control Protocol to control the python script's memory usage.
> And heartbeat tuple needs a separate queue(pending_heartbeats), and Child-Process handle heartbeat tuple at high priority. [~kabhwan] wish to hear your opinion.



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