F2

An experimental lock manager for Neo4j 3.2.x and 3.3.x.

NOTE

This is a personal proof of concept, it is not in any way supported by Neo Technology or anyone else. This code is not production ready. Bugs in here may cause irrecoverable data corruption, use at your own risk.

Usage

Put f2.jar in the plugins directory of your Neo4j 3.2.x or 3.3.x system.
Add unsupported.dbms.lock_manager=f2 to your neo4j.conf
Restart Neo4j

Configuration

F2 provides one configuration option to tune the number of partitions to use, a higher number here means more memory overhead but less contention:

unsupported.dbms.f2.partitions=128

The partition number must be a factor of 2.

Building

mvn clean package -P build-extension

Overview

F2 is a partitioned lock manager, allowing concurrent work to happen in separate partitions, but ordering accesses within one partition using a semaphore.

F2 offers several nice features:

Deterministic deadlock detection with no false positives
Exact deadlock descriptions
Thread notification-based waiting, using substantially less system resources than Forseti

Good place to start reading is in F2Client#acquire.

Performance

Please see F2Locks_PerfTest for micro benchmarks.

Performance compared to Forseti at d69c50c on Intel(R) Core(TM) i7-6600U CPU @ 2.60GHz:

Benchmark                                             Mode  Cnt     Score      Error   Units
F2Locks_PerfTest.f2AcquireContendedExclusive         thrpt    5   528.829 ±   89.808  ops/ms
F2Locks_PerfTest.forsetiAcquireContendedExclusive    thrpt    5  1213.495 ±  252.209  ops/ms

F2Locks_PerfTest.f2AcquireContendedShared            thrpt    5  9645.799 ± 1132.557  ops/ms
F2Locks_PerfTest.forsetiAcquireContendedShared       thrpt    5  5540.280 ± 1330.020  ops/ms

F2Locks_PerfTest.f2SchemaExclusiveCombintation       thrpt    5    12.366 ±   30.350  ops/ms
F2Locks_PerfTest.forsetiSchemaExclusiveCombintation  thrpt    5     6.329 ±    2.242  ops/ms

License

AGPL

jakewins/f2