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https://issues.apache.org/jira/browse/MESOS-2309?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14316472#comment-14316472
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Till Toenshoff commented on MESOS-2309:
---------------------------------------
Seems this equality issue is rooted in the fact that protobuf's optional
default values let "has_...." fail when the default is used instead of an
explicit set value.
>From https://code.google.com/p/protobuf-c/wiki/Default_Values
{quote}
h4. Default-Values for Optional Fields
Once again, the value is used for initializing a fresh instance, and it can be
seen if you deserialize a message missing an optional field.
Except for string and messages, all optional fields have a corresponding
has_field member of the generated C struct. In the case of being set to a
default value, the has_field member will NOT be set, but the "field" member
itself will be set to the default value. Such values will only be serialized if
the has_field flag is set.
{quote}
> Mesos rejects ExecutorInfo as incompatible when there is no functional
> difference
> ---------------------------------------------------------------------------------
>
> Key: MESOS-2309
> URL: https://issues.apache.org/jira/browse/MESOS-2309
> Project: Mesos
> Issue Type: Bug
> Reporter: Zameer Manji
> Assignee: Joerg Schad
> Priority: Minor
>
> In AURORA-1076 it was discovered that if an ExecutorInfo was changed such
> that a previously unset optional field with a default value was changed to
> have the field set with the default value, it would be rejected as not
> compatible.
> For example if we have an ExecutorInfo with a CommandInfo with the {{shell}}
> attribute unset and then we change the CommandInfo to set the {{shell}}
> attribute to true Mesos will reject the task with:
> {noformat}
> I0130 21:50:05.373389 50869 master.cpp:3441] Sending status update TASK_LOST
> (UUID: 82ef615c-0d59-4427-95d5-80cf0e52b3fc) for task
> system-gc-c89c0c05-200c-462e-958a-ecd7b9a76831 of framework
> 201103282247-0000000019-0000 'Task has invalid ExecutorInfo (existing
> ExecutorInfo with same ExecutorID is not compatible).
> {noformat}
> This is not intuitive because the default value of the {{shell}} attribute is
> true. There should be no difference between not setting an optional field
> with a default value and setting that field to the default value.
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