Issue - 108 - Parallel Compensation

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Issue - 108 - Parallel Compensation

Status: open
Area: Compensation
Date added: 20 Mar 2004
Submitter: Yaron Y. Goland
Date submitted: 19 March 2004
Description: If someone is willing to do manual compensation then they could, at 
least in theory, do parallel compensation today by including calls to 
compensate with the names of the child scopes inside of a flow. E.g.
compensationHandler
    flow
       compensate scope="foo"
       compensate scope="bar"
In the case of the default compensation handler section 13.3.3 of the 
latest editor's draft states "If the compensation handler for a scope is 
absent, the default compensation handler invokes the compensation 
handlers for the immediately enclosed scopes in the reverse order of the 
completion of those scopes."

But, if one felt deeply sneaky, one could interpret the spec to mean that one must start the compensation handlers in the completion order but there is no requirement that one must necessarily wait for a compensation handler to complete execution before starting the next one. In other words, one could interpret the current language as allowing default compensation handlers to execute child compensation handlers in parallel.

The purpose of this issue is to clarify the ability to run compensation handlers in parallel so that programmers know what to expect. Since we now allow compensation handlers to manipulate common variables it is critical that programmers know if their handlers can run in parallel.

At a minimum this issue should answer the following questions:

• Is it ever legal to run compensation handlers in parallel?
• If so, is it legal for default compensation handlers to execute child compensation handlers in parallel?
• If so, do we want to provide a way to stop a default compensation handler from running its child compensation handlers in parallel?
• Should it ever be legal to run the child compensation handlers of scopes inside of a while loop in parallel?

Changes: 20 Mar 2004 - new issue

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