zodb / relstorage / 1085

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travis-ci

Speed up conflict resolution.

- Get committed data in bulk;
- Store replacement data in bulk.

This eliminates lots of database queries if there's more than one
conflict. Since this happens while rows are locked, the faster this
is, and the fewer round trips, the better. Results are 40-90%
improvements, depending on cache configuration.

+---------------------------------------------+-----------------------------------------+-----------------------------------------+
| Benchmark                                   | pg11-c10-proc-conflicts-uncached-master | pg11-c10-proc-conflicts-uncached-branch |
+=============================================+=========================================+=========================================+
| psycopg2_hf: update 100 conflicting objects | 1.55 sec                                | 878 ms: 1.76x faster (-43%)             |
+---------------------------------------------+-----------------------------------------+-----------------------------------------+

+---------------------------------------------+---------------------------------------+---------------------------------------+
| Benchmark                                   | pg11-c10-proc-conflicts-cached-master | pg11-c10-proc-conflicts-cached-branch |
+=============================================+=======================================+=======================================+
| psycopg2_hf: update 100 conflicting objects | 789 ms                                | 94.1 ms: 8.39x faster (-88%)          |
+---------------------------------------------+---------------------------------------+---------------------------------------+

+------------------------------------------------+-----------------------------------------+-----------------------------------------+
| Benchmark                                      | my57-c10-proc-conflicts-uncached-master | my57-c10-proc-conflicts-uncached-branch |
+================================================+======================... (continued)

89 of 89 new or added lines in 16 files covered. (100.0%)

16029 of 17156 relevant lines covered (93.43%)

3.7 hits per line