Retention service hangs and does not remove old shards #25054
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gwossum
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Jun 11, 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. closes: #25054
gwossum
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Jun 13, 2024
* fix: prevent retention service from hanging 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. closes: #25054
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Can you create port issues for all the repos and branches, @gwossum ? |
chengshiwen
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Aug 27, 2024
* fix: prevent retention service from hanging 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. closes: influxdata#25054
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Under certain conditions, the retention service can become hung waiting on a shard's reference count to drop to zero. When this happens, no other shards can be removed by the retention service. This can eventually result in high disk usage.
The attached goroutine trace shows a system exhibiting the issue. The retention service is stuck on waiting on the WaitGroup used to indicate that the references to the shard have dropped to zero.
goroutine.txt
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