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Port #25055 to main-2.x #25076

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gwossum opened this issue Jun 21, 2024 · 0 comments
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Port #25055 to main-2.x #25076

gwossum opened this issue Jun 21, 2024 · 0 comments
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area/storage area/2.x OSS 2.0 related issues and PRs team/edge

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gwossum commented Jun 21, 2024

Port #25055 (retention service hang fix) to main-2.x

@gwossum gwossum added area/storage area/2.x OSS 2.0 related issues and PRs team/edge labels Jun 21, 2024
@gwossum gwossum self-assigned this Jun 21, 2024
gwossum added a commit that referenced this issue Jun 21, 2024
Fix issue that can cause the retention service to hang waiting on a
`Shard.Close` call. When this occurs, no other shards will be deleted
by the retention service. This is usually noticed as an increase in
disk usage because old shards are not cleaned up.

The fix adds to new methods to `Store`, `SetShardNewReadersBlocked`
and `InUse`. `InUse` can be used to poll if a shard has active readers,
which the retention service uses to skip over in-use shards to prevent
the service from hanging. `SetShardNewReadersBlocked` determines if
new read access may be granted to a shard. This is required to prevent
race conditions around the use of `InUse` and the deletion of shards.

If the retention service skips over a shard because it is in-use, the
shard will be checked again the next time the retention service is run.
It can be deleted on subsequent checks if it is no longer in-use. If
the shards is stuck in-use, the retention service will not be able to
delete the shards, which can be observed in the logs for manual
intervention. Other shards can still be deleted by the retention service
even if a shard is stuck with readers.

This is a port of ad68ec8 from master-1.x to main-2.x.

closes: #25076
(cherry picked from commit b4bd607)
gwossum added a commit that referenced this issue Jun 24, 2024
* fix: prevent retention service from hanging (#25055)

Fix issue that can cause the retention service to hang waiting on a
`Shard.Close` call. When this occurs, no other shards will be deleted
by the retention service. This is usually noticed as an increase in
disk usage because old shards are not cleaned up.

The fix adds to new methods to `Store`, `SetShardNewReadersBlocked`
and `InUse`. `InUse` can be used to poll if a shard has active readers,
which the retention service uses to skip over in-use shards to prevent
the service from hanging. `SetShardNewReadersBlocked` determines if
new read access may be granted to a shard. This is required to prevent
race conditions around the use of `InUse` and the deletion of shards.

If the retention service skips over a shard because it is in-use, the
shard will be checked again the next time the retention service is run.
It can be deleted on subsequent checks if it is no longer in-use. If
the shards is stuck in-use, the retention service will not be able to
delete the shards, which can be observed in the logs for manual
intervention. Other shards can still be deleted by the retention service
even if a shard is stuck with readers.

This is a port of ad68ec8 from master-1.x to main-2.x.

closes: #25076
(cherry picked from commit b4bd607)
@gwossum gwossum closed this as completed Jun 28, 2024
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