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Timed out cluster state publication is applied in an empty context #53751

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DaveCTurner opened this issue Mar 18, 2020 · 2 comments
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Timed out cluster state publication is applied in an empty context #53751

DaveCTurner opened this issue Mar 18, 2020 · 2 comments
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>bug :Distributed Coordination/Cluster Coordination Cluster formation and cluster state publication, including cluster membership and fault detection. Team:Distributed (Obsolete) Meta label for distributed team (obsolete). Replaced by Distributed Indexing/Coordination.

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@DaveCTurner
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DaveCTurner commented Mar 18, 2020

Today the elected master waits for all other nodes to acknowledge a cluster state publication before applying it locally, although it will time out if the other nodes are not all fast enough. The timeout is performed by a delayed action scheduled with ThreadPool#schedule at the start of the publication.

ThreadPool#schedule does not preserve the context of the caller, however, which means that the cluster state is applied with an empty context rather than being in the system context. This means that any cluster state appliers which use the context of the application (e.g. capture it for future use, or try and send transport messages) will not work correctly if security is enabled.

One such case was introduced in #48430: retention lease syncs now run in the context in which the IndexService was created, which happens during cluster state application. Thus if the elected master is also a data node, and the cluster state publication that assigns a shard to it times out after committing, then the retention lease syncs will fail.

If affected, the workaround is to restart the elected master.

This exposes a gap in the CoordinatorTests framework which does not properly simulate how thread contexts behave.

@DaveCTurner DaveCTurner added >bug :Distributed Coordination/Cluster Coordination Cluster formation and cluster state publication, including cluster membership and fault detection. labels Mar 18, 2020
@elasticmachine
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Pinging @elastic/es-distributed (:Distributed/Cluster Coordination)

DaveCTurner added a commit to DaveCTurner/elasticsearch that referenced this issue Mar 19, 2020
Today cluster states are sometimes (rarely) applied in the default context
rather than system context, which means that any appliers which capture their
contexts cannot do things like remote transport actions when security is
enabled.

There are at least two ways that we end up applying the cluster state in the
default context:

1. locally applying a cluster state that indicates that the master has failed
2. the elected master times out while waiting for a response from another node

This commit ensures that cluster states are always applied in the system
context.

Mitigates elastic#53751
DaveCTurner added a commit that referenced this issue Mar 19, 2020
Today cluster states are sometimes (rarely) applied in the default context
rather than system context, which means that any appliers which capture their
contexts cannot do things like remote transport actions when security is
enabled.

There are at least two ways that we end up applying the cluster state in the
default context:

1. locally applying a cluster state that indicates that the master has failed
2. the elected master times out while waiting for a response from another node

This commit ensures that cluster states are always applied in the system
context.

Mitigates #53751
DaveCTurner added a commit that referenced this issue Mar 19, 2020
Today cluster states are sometimes (rarely) applied in the default context
rather than system context, which means that any appliers which capture their
contexts cannot do things like remote transport actions when security is
enabled.

There are at least two ways that we end up applying the cluster state in the
default context:

1. locally applying a cluster state that indicates that the master has failed
2. the elected master times out while waiting for a response from another node

This commit ensures that cluster states are always applied in the system
context.

Mitigates #53751
@jimczi jimczi removed the v7.6.2 label Mar 24, 2020
@rjernst rjernst added the Team:Distributed (Obsolete) Meta label for distributed team (obsolete). Replaced by Distributed Indexing/Coordination. label May 4, 2020
@ywelsch
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ywelsch commented Jul 23, 2020

Closed by #57792

@ywelsch ywelsch closed this as completed Jul 23, 2020
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Labels
>bug :Distributed Coordination/Cluster Coordination Cluster formation and cluster state publication, including cluster membership and fault detection. Team:Distributed (Obsolete) Meta label for distributed team (obsolete). Replaced by Distributed Indexing/Coordination.
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