Details
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Task
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Status: Closed (View Workflow)
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Critical
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Resolution: Fixed
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None
Description
When lf_delete() — for example — searches in the hash it may need to allocate and insert a new dummy node, the latter may fail with OOM. The caller normally doesn't expect OOM from searches or deletes and it's not always easy to handle OOM there.
Instead lf_delete() and lf_search() can be changed never to return OOM. Indeed, when a search cannot insert a new dummy node, it simply needs to start searching from the previous dummy node, which is guaranteed to exist.
It's even easier in lf_hash_iterate() — it only ever looks for the very first bucket, dummy node 0. If that node does not exists, the hash is most certainly empty.
Attachments
Activity
It looks very good, thanks for implementing!
I just have one more wish (better to be implemented separately): make lf_hash_get_pins() never to return OOM.
One way to solve this is to allow to preallocate max possible number of pins (e.g. table cache doesn't need more pins than max_connections?).
Another way is to have static pins protected by mutex. They will be returned on OOM only.
svoj, please, take a look at the patch.
https://github.com/MariaDB/server/tree/bb-lf-no-oom