Optimize tid lock table #382
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By making the ets table mnesia_tid_locks an ordered set instead of a bag, the time for inserting locks for a transaction with large number of locks is reduced significantly.
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Patch has passed first testings and has been assigned to be reviewed |
| @@ -509,7 +509,8 @@ release_remote_non_pending(Node, Pending) -> | |||
| %% running at the failed node and also simply remove all | |||
| %% queue'd requests back to the failed node | |||
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| AllTids = ?ets_match(mnesia_tid_locks, {'$1', '_', '_'}), | |||
| AllTids0 = ?ets_match(mnesia_tid_locks, {{'$1', '_', '_'}}), | |||
| AllTids = lists:usort(AllTids0), | |||
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Is this line (513) needed? Being the table an ordered set, it would already be sorted and without duplicates.
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The line is not needed, but it is an optimization.
The '$1' is just the first element of the key, not the whole key. It will
probably be sorted, but it will not be unique. In the earlier code '$1'
referred to the whole key, which then was the tid, but still was not unique
since it was a bag table.
The code obviously handles duplicates, but there is no reason to keep them.
Quite the opposite.
On Aug 31, 2014 9:55 PM, "Fabio Ticconi" notifications@github.com wrote:
In lib/mnesia/src/mnesia_locker.erl:
@@ -509,7 +509,8 @@ release_remote_non_pending(Node, Pending) ->
%% running at the failed node and also simply remove all
%% queue'd requests back to the failed node
- AllTids = ?ets_match(mnesia_tid_locks, {'$1', '', ''}),
- AllTids0 = ?ets_match(mnesia_tid_locks, {{'$1', '', ''}}),
- AllTids = lists:usort(AllTids0),
Is this line needed? Being the table an ordered set, it would already be
sorted and without duplicates.—
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https://github.com/erlang/otp/pull/382/files#r16936609.
By making the ets table mnesia_tid_locks an ordered set instead of a
bag, the time for inserting locks for a transaction with large number
of locks is reduced significantly.