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| fenway_frank |
 Posted: Fri Mar 30, 2012 1:15 pm Post subject: thread safety of environment tree variables |
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Apprentice
Joined: 21 Oct 2011
Posts: 43
Location: Boston, MA USA
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hello.
is the environment tree structure (especially the 'variables' subtree) thread safe? if i assign a variable within an esql node, i presume the assignment itself is thread safe within the execution of the message flow. most important, subsequent requests/instantiations of same msgflow will create a separate environment tree. that is my understanding, pls confirm.
also, why doesn't jcn support access to the same environment tree? |
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| mgk |
| Posted: Fri Mar 30, 2012 1:18 pm Post subject: |
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Padawan
Joined: 31 Jul 2003
Posts: 1642
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| Quote: |
| is the environment tree structure (especially the 'variables' subtree) thread safe |
Yes
| Quote: |
| if i assign a variable within an esql node, i presume the assignment itself is thread safe within the execution of the message flow |
Yes
| Quote: |
| most important, subsequent requests/instantiations of same msgflow will create a separate environment tree |
Yes, a new Environment tree is created for each message through a flow.
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| that is my understanding, pls confirm |
Done.
| Quote: |
| why doesn't jcn support access to the same environment tree? |
It does, look again at the API.
Kind Regards,
_________________
MGK
The postings I make on this site are my own and don't necessarily represent IBM's positions, strategies or opinions. |
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| fenway_frank |
| Posted: Fri Mar 30, 2012 1:25 pm Post subject: |
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Apprentice
Joined: 21 Oct 2011
Posts: 43
Location: Boston, MA USA
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| @mgk - thx for quick reply. if i increase the number within msgflow "additional instances" property > 0, my understand is that (1+additional instances) message flow instances are instantiated at eg startup and ready to receive traffic. how, if at all, does this effect the behavior of the environment tree? thx! |
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| fjb_saper |
| Posted: Fri Mar 30, 2012 1:38 pm Post subject: |
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Grand High Poobah
Joined: 18 Nov 2003
Posts: 20756
Location: LI,NY
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| fenway_frank wrote: |
| @mgk - thx for quick reply. if i increase the number within msgflow "additional instances" property > 0, my understand is that (1+additional instances) message flow instances are instantiated at eg startup and ready to receive traffic. how, if at all, does this effect the behavior of the environment tree? thx! |
I doesn't because as stated the tree is threadsafe...
Now if you are playing with Shared variables, then the content (of the shared variables) is no longer "thread-safe" as it can be changed by the other instances of the flow... 
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MQ & Broker admin |
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| fenway_frank |
| Posted: Fri Mar 30, 2012 1:41 pm Post subject: |
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Apprentice
Joined: 21 Oct 2011
Posts: 43
Location: Boston, MA USA
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yes, understood that shared variables are another matter altogether.
thx for answering my questions. |
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| fenway_frank |
| Posted: Fri Mar 30, 2012 6:02 pm Post subject: |
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Apprentice
Joined: 21 Oct 2011
Posts: 43
Location: Boston, MA USA
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| Just to be crystal clear, my prior questions were specifically targeting the Environment tree and not the Local Environment Tree. Both have concept of variables "scratch pad" section but i intend to use Environment.variables (not LocalEnvironment.variables) to carry custom data across the message flow. |
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| fjb_saper |
| Posted: Sat Mar 31, 2012 6:14 am Post subject: |
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Grand High Poobah
Joined: 18 Nov 2003
Posts: 20756
Location: LI,NY
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| fenway_frank wrote: |
| Just to be crystal clear, my prior questions were specifically targeting the Environment tree and not the Local Environment Tree. Both have concept of variables "scratch pad" section but i intend to use Environment.variables (not LocalEnvironment.variables) to carry custom data across the message flow. |
It is thread safe and different for each instance of the flow.
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| mqjeff |
| Posted: Sat Mar 31, 2012 10:03 am Post subject: |
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Grand Master
Joined: 25 Jun 2008
Posts: 17447
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| fenway_frank wrote: |
| Just to be crystal clear, my prior questions were specifically targeting the Environment tree and not the Local Environment Tree. Both have concept of variables "scratch pad" section but i intend to use Environment.variables (not LocalEnvironment.variables) to carry custom data across the message flow. |
Just to be crystal clear.
BOTH TREES ARE COMPLETELY THREAD SAFE. |
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| rekarm01 |
| Posted: Sun Apr 01, 2012 3:44 pm Post subject: |
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Grand Master
Joined: 25 Jun 2008
Posts: 1415
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| mqjeff wrote: |
Just to be crystal clear.
BOTH TREES ARE COMPLETELY THREAD SAFE. |
Before anyone asks, the Root and ExceptionList trees are also completely thread safe.
However, this only applies to threads created by the broker itself. Within a message flow instance, an external procedure, non-ESQL compute node, or user-defined extension could create its own threads, unbeknownst to the broker, but these non-broker threads must not use the broker API to access any message trees. |
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