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https://issues.apache.org/jira/browse/STORM-738?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14598420#comment-14598420
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Jungtaek Lim commented on STORM-738:
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[~dashengju]
Via STORM-738 I removed the heartbeat design constraint, by let subprocess
updates local pid file periodically.
If it is accepted, whole heartbeat timeout issues should be resolved.
Could you check it makes sense?
> 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
> 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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