[
https://issues.apache.org/jira/browse/NIFI-3406?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Joseph Percivall updated NIFI-3406:
-----------------------------------
Description:
The issue prompting this is that JRuby's default configuration uses a Singleton
scope[1]. So all threads will see the same runtime and variables. This means if
a FlowFile is currently running within the body of a script, and a new one
comes in, the first thread will use the new variables (session, flowfile,
etc.). This is obviously a problem and can lead "flowfile not known in this
session" and livelocks in the FF repo due to multiple sessions updating the
same flowfile[2].
ExecuteScript needs to
1: give more information about the script engine being run
2: provide more configuration options for the script engine it self
3: warn the user about the nuances of script engines and how they are not
maintained by Apache NiFi so may not follow our best practices.
This also probably
[1]
https://github.com/jruby/jruby/blob/master/core/src/main/java/org/jruby/embed/ScriptingContainer.java#L198
Specifically the line: "However, the default, singleton local context scope
behave slightly different. If Ruby runtime has been already instantiated by
another ScriptingContainer, application, etc, the same runtime will be used."
[2]
https://github.com/JPercivall/nifi/blob/1be08714731f01347ac1f98e18047fe7d9ab8afd/nifi-commons/nifi-write-ahead-log/src/main/java/org/wali/MinimalLockingWriteAheadLog.java#L69-L69
was:
The issue prompting this is that JRuby's default configuration uses a Singleton
scope[1]. So all threads will see the same runtime and variables. This means if
a FlowFile is currently running within the body of a script, and a new one
comes in, the first thread will use the new variables (session, flowfile,
etc.). This is obviously a problem and can lead "flowfile not known in this
session" and livelocks in the FF repo due to multiple sessions updating the
same flowfile[2].
ExecuteScript needs to
1: give more information about the script engine being run
2: provide more configuration options for the script engine it self
3: warn the user about the nuances of script engines and how they are not
maintained by Apache NiFi so may not follow our best practices.
[1]
https://github.com/jruby/jruby/blob/master/core/src/main/java/org/jruby/embed/ScriptingContainer.java#L198
Specifically the line: "However, the default, singleton local context scope
behave slightly different. If Ruby runtime has been already instantiated by
another ScriptingContainer, application, etc, the same runtime will be used."
[2]
https://github.com/JPercivall/nifi/blob/1be08714731f01347ac1f98e18047fe7d9ab8afd/nifi-commons/nifi-write-ahead-log/src/main/java/org/wali/MinimalLockingWriteAheadLog.java#L69-L69
> Multiple Improvements needed to ExecuteScript ScriptEngines
> configuration/information
> -------------------------------------------------------------------------------------
>
> Key: NIFI-3406
> URL: https://issues.apache.org/jira/browse/NIFI-3406
> Project: Apache NiFi
> Issue Type: Improvement
> Affects Versions: 1.1.1
> Reporter: Joseph Percivall
> Priority: Blocker
>
> The issue prompting this is that JRuby's default configuration uses a
> Singleton scope[1]. So all threads will see the same runtime and variables.
> This means if a FlowFile is currently running within the body of a script,
> and a new one comes in, the first thread will use the new variables (session,
> flowfile, etc.). This is obviously a problem and can lead "flowfile not known
> in this session" and livelocks in the FF repo due to multiple sessions
> updating the same flowfile[2].
> ExecuteScript needs to
> 1: give more information about the script engine being run
> 2: provide more configuration options for the script engine it self
> 3: warn the user about the nuances of script engines and how they are not
> maintained by Apache NiFi so may not follow our best practices.
> This also probably
> [1]
> https://github.com/jruby/jruby/blob/master/core/src/main/java/org/jruby/embed/ScriptingContainer.java#L198
> Specifically the line: "However, the default, singleton local context scope
> behave slightly different. If Ruby runtime has been already instantiated by
> another ScriptingContainer, application, etc, the same runtime will be used."
> [2]
> https://github.com/JPercivall/nifi/blob/1be08714731f01347ac1f98e18047fe7d9ab8afd/nifi-commons/nifi-write-ahead-log/src/main/java/org/wali/MinimalLockingWriteAheadLog.java#L69-L69
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
