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Call engine tx cache cleanup

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Summary:
After the commit log was cleared there was some transaction that tried to acquire
a lock on an object that was taken by a transaction that was not longer active on
the worker. Inquring the commit log about that transaction causes a crash since
the commit log is cleared of that transaction.

Solution is to clear the transaction cache before clearing the commit log, which
forces the transactions to release their locks and as such their ids will never be
queried through the commit log in the future.

Reviewers: florijan, msantl

Reviewed By: msantl

Subscribers: pullbot

Differential Revision: https://phabricator.memgraph.io/D1342
This commit is contained in:
Dominik Gleich 2018-04-09 11:24:11 +02:00
parent 7b88e514b8
commit 29234067d9
1 changed files with 8 additions and 0 deletions
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8
src/database/storage_gc_worker.hpp
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@ -4,6 +4,7 @@
#include "database/storage_gc.hpp"
#include "distributed/storage_gc_rpc_messages.hpp"
#include "transactions/engine_worker.hpp"
#include "transactions/transaction.hpp"
namespace database {
@ -19,6 +20,13 @@ class StorageGcWorker : public StorageGc {
void CollectCommitLogGarbage(tx::transaction_id_t oldest_active) final {
auto safe_to_delete = GetClogSafeTransaction(oldest_active);
if (safe_to_delete) {
// We first need to delete transactions that we can delete to be sure that
// the locks are released as well. Otherwise some new transaction might
// try to aquire a lock which hasn't been released (if the transaction
// cache cleaner was not scheduled at this time), and take a look into the
// commit log which no longer contains that transaction id
dynamic_cast<tx::WorkerEngine &>(tx_engine_)
.ClearTransactionalCache(*safe_to_delete);
master_client_pool_.Call<distributed::RanLocalGcRpc>(*safe_to_delete,
worker_id_);
tx_engine_.GarbageCollectCommitLog(*safe_to_delete);