diff options
| -rw-r--r-- | src/include/txn.i | 9 | ||||
| -rw-r--r-- | src/txn/txn_ckpt.c | 7 |
2 files changed, 11 insertions, 5 deletions
diff --git a/src/include/txn.i b/src/include/txn.i index 40e2a6175d6..f5ca44c2ada 100644 --- a/src/include/txn.i +++ b/src/include/txn.i @@ -357,8 +357,13 @@ __wt_txn_id_alloc(WT_SESSION_IMPL *session, bool publish) WT_PUBLISH(WT_SESSION_TXN_STATE(session)->id, id); } - ++txn_global->current; - __wt_spin_unlock(session, &txn_global->id_lock); + /* + * Even though we are in a spinlock, readers are not. We rely on + * atomic reads of the current ID to create snapshots, so for unlocked + * reads to be well defined, we must use an atomic increment here. + */ + (void)__wt_atomic_addv64(&txn_global->current, 1); + __wt_spin_unlock(session, &txn_global->id_lock); return (id); } diff --git a/src/txn/txn_ckpt.c b/src/txn/txn_ckpt.c index fdbda26b781..27e18b254b8 100644 --- a/src/txn/txn_ckpt.c +++ b/src/txn/txn_ckpt.c @@ -441,14 +441,15 @@ __txn_checkpoint(WT_SESSION_IMPL *session, const char *cfg[]) * Start the checkpoint for real. * * Bump the global checkpoint generation, used to figure out whether - * checkpoint has visited a tree. There is no need for this to be - * atomic: it is only written while holding the checkpoint lock. + * checkpoint has visited a tree. Use an atomic increment even though + * we are single-threaded because readers of the checkpoint generation + * don't hold the checkpoint lock. * * We do need to update it before clearing the checkpoint's entry out * of the transaction table, or a thread evicting in a tree could * ignore the checkpoint's transaction. */ - ++txn_global->checkpoint_gen; + (void)__wt_atomic_addv64(&txn_global->checkpoint_gen, 1); WT_STAT_FAST_CONN_SET(session, txn_checkpoint_generation, txn_global->checkpoint_gen); |