Prevent deadlock when notifying shard of ledger #3683
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| { | ||
| JLOG(j_.error()) << "shard " << index_ | ||
| << " missing acquire SQLite database"; | ||
| auto const scopedCount{makeBackendCount()}; |
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On line 153 of this file (not in this changeset), we check the backendCount_ and exit early if in use. We also lock mutex_ but not storedMutex_ there. The old code would have closed the backend_ but the new code may not.
Who closes backend_ in such a case? Is it DatabaseShardImp::sweep()? If nobody does, an easy fix is to lock the storedMutex there as well. If it's not an issue, the of couse fine as-is.
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Yes, DatabaseShardImp::sweep() will close it or the shard Dtor. I don't see an issue with tryClose and storedMutex_ as is, but maybe I missed something you saw.
ghost
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undertome
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High Level Overview of Change
This change is primarily about preventing a potential thread deadlock when notifying shards on ledger completions.
Context of Change
Shards are notified by the inbound ledger process when pertaining ledgers have been acquired. Upon notification, the SQLite database is populated with ledger data. If the ledger data resides in the same shard, it is possible to encounter a deadlock when shard fetch calls are made while storing to the SQLite database.
Type of Change