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Summary: The current locktree implementation stores the address of the PessimisticTransactions object as the TXNID. However, when a transaction is blocked on a lock, it records the list of waitees with conflicting locks using the rocksdb assigned TransactionID. This is performed by calling GetID() on PessimisticTransactions objects of the waitees, and then recorded in the waiter's list. However, there is no guarantee the objects are valid when recording the waitee list during the conflict callbacks because the waitee could have released the lock and freed the PessimisticTransactions object. The waitee/txnid values are only valid PessimisticTransaction objects while the mutex for the root of the locktree is held. The simplest fix for this problem is to use the address of the PessimisticTransaction as the TransactionID so that it is consistent with its usage in the locktree. The TXNID is only converted back to a PessimisticTransaction for the report_wait callbacks. Since these callbacks are now all made within the critical section where the lock_request queue mutx is held, these conversions will be safe. Otherwise, only the uint64_t TXNID of the waitee is registerd with the waiter transaction. The PessimisitcTransaction object of the waitee is never referenced. The main downside of this approach is the TransactionID will not change if the PessimisticTransaction object is reused for new transactions. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9898 Test Plan: Add a new test case and run unit tests. Also verified with MyRocks workloads using range locks that the crash no longer happens. Reviewed By: riversand963 Differential Revision: D35950376 Pulled By: hermanlee fbshipit-source-id: 8c9cae272e23e487fc139b6a8ed5b8f8f24b1570 |
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| .. | ||
| range_tree | ||
| range_lock_manager.h | ||
| range_locking_test.cc | ||