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https://issues.apache.org/jira/browse/MESOS-9000?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16587188#comment-16587188
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Alexander Rukletsov edited comment on MESOS-9000 at 8/21/18 9:12 AM:
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On the 1.8.0-dev:
{noformat}
commit 613741147123563f7b68e900c321e7f5db8236fe
Author: Benno Evers <bev...@mesosphere.com>
AuthorDate: Tue Aug 21 10:58:35 2018 +0200
Commit: Alexander Rukletsov <al...@apache.org>
CommitDate: Tue Aug 21 11:04:37 2018 +0200
Changed operator API to notify subscribers on every status change.
Prior to this change, the master would only send `TaskUpdated`
messages to subscribers when the latest known task state on the
agent changed.
This implied that schedulers could not reliably wait for the status
information corresponding to specific state updates, i.e.,
`TASK_RUNNING`, since there is no guarantee that subscribers get
notified during the time when this status update will be included in
the status field.
After this change, `TaskUpdated` messages are sent whenever the latest
acknowledged state of the task changes.
Review: https://reviews.apache.org/r/67575/
{noformat}
was (Author: alexr):
{noformat}
commit 613741147123563f7b68e900c321e7f5db8236fe
Author: Benno Evers <bev...@mesosphere.com>
AuthorDate: Tue Aug 21 10:58:35 2018 +0200
Commit: Alexander Rukletsov <al...@apache.org>
CommitDate: Tue Aug 21 11:04:37 2018 +0200
Changed operator API to notify subscribers on every status change.
Prior to this change, the master would only send `TaskUpdated`
messages to subscribers when the latest known task state on the
agent changed.
This implied that schedulers could not reliably wait for the status
information corresponding to specific state updates, i.e.,
`TASK_RUNNING`, since there is no guarantee that subscribers get
notified during the time when this status update will be included in
the status field.
After this change, `TaskUpdated` messages are sent whenever the latest
acknowledged state of the task changes.
Review: https://reviews.apache.org/r/67575/
{noformat}
> Operator API event stream can miss task status updates.
> -------------------------------------------------------
>
> Key: MESOS-9000
> URL: https://issues.apache.org/jira/browse/MESOS-9000
> Project: Mesos
> Issue Type: Bug
> Components: HTTP API
> Reporter: Benno Evers
> Assignee: Benno Evers
> Priority: Major
> Labels: mesosphere
> Fix For: 1.7.0
>
>
> As of now, the master only sends TaskUpdated messages to subscribers when the
> latest known task state on the agent changed:
> {noformat}
> // src/master/master.cpp
> if (!protobuf::isTerminalState(task->state())) {
> if (status.state() != task->state()) {
> sendSubscribersUpdate = true;
> }
> task->set_state(latestState.getOrElse(status.state()));
> }
> {noformat}
> The latest state is set like this:
> {noformat}
> // src/messages/messages.proto
> message StatusUpdate {
> [...]
> // This corresponds to the latest state of the task according to the
> // agent. Note that this state might be different than the state in
> // 'status' because task status update manager queues updates. In
> // other words, 'status' corresponds to the update at top of the
> // queue and 'latest_state' corresponds to the update at bottom of
> // the queue.
> optional TaskState latest_state = 7;
> }
> {noformat}
> However, the `TaskStatus` message included in an `TaskUpdated` event is the
> event at the bottom of the queue when the update was sent.
> So we can easily get in a situation where e.g. the first TaskUpdated has
> .status.state == TASK_STARTING and .state == TASK_RUNNING, and the second
> update with .status.state == TASK_RUNNNING and .state == TASK_RUNNING would
> not get delivered because the latest known state did not change.
> This implies that schedulers can not reliably wait for the status information
> corresponding to specific task state, since there is no guarantee that
> subscribers get notified during the time when this status update will be
> included in the status field.
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