ACP is Attribyte's open-source JDBC connection pool. It is designed to support the high throughput, concurrency, tuning, monitoring and reporting typically required to support production application servers. Connection pools are composed of segments that are used, activated, and deactivated in sequence in response to connection demand. When active, a segment provides logical connections from a fixed-size pool of physical connections.
ACP was originally created in 2010. I was motivated to create ACP because, at the time, I couldn't find a pool that was instrumented the way I needed, or capable of being carefully tuned to supply "backpressure" when flooded with connection requests. (The best candidate, BoneCP, was just being developed. HikariCP is quite new.) For several years it reliably provided connections for Gawker Media's publishing system. It was migrated from Bitbucket in 2014. While moving it to Github, a few things have been tweaked:
- Now requires Java 8.
- Added more control of close behavior when "activity timeout" is configured.
- Added ability to disable statement tracking.
- Removed XML/DOM-based configuration in favor of HOCON (or
Properties). - Simplified programmatic configuration.
- Better metrics.
Here's the result of a "quick" run of the HikariCP benchmark. Not bad. The connection pool has never been a bottleneck in any Attribyte system, so I have spent little time trying to optimize ACP. Note that pool instrumentation is always enabled (timing, metring of connection acquisitions, etc.). Turning this off might improve the score, but I've never experienced a situation where (possibly) better connection pool performance was more important than pool monitoring.
# Run complete. Total time: 00:09:32
Benchmark (maxPoolSize) (pool) Mode Samples Score Score error Units
c.z.h.b.ConnectionBench.cycleCnnection 32 hikari thrpt 16 10928.401 165.642 ops/ms
c.z.h.b.ConnectionBench.cycleCnnection 32 bone thrpt 16 5797.225 64.904 ops/ms
c.z.h.b.ConnectionBench.cycleCnnection 32 tomcat thrpt 16 1498.525 119.418 ops/ms
c.z.h.b.ConnectionBench.cycleCnnection 32 c3p0 thrpt 16 82.673 3.397 ops/ms
c.z.h.b.ConnectionBench.cycleCnnection 32 vibur thrpt 16 4971.874 70.311 ops/ms
c.z.h.b.ConnectionBench.cycleCnnection 32 acp thrpt 16 3189.405 101.285 ops/ms
c.z.h.b.StatementBench.cycleStatement 32 hikari thrpt 16 73408.710 4079.799 ops/ms
c.z.h.b.StatementBench.cycleStatement 32 bone thrpt 8 11467.816 436.378 ops/ms
c.z.h.b.StatementBench.cycleStatement 32 tomcat thrpt 16 25277.900 495.015 ops/ms
c.z.h.b.StatementBench.cycleStatement 32 c3p0 thrpt 16 6696.266 54.554 ops/ms
c.z.h.b.StatementBench.cycleStatement 32 vibur thrpt 16 13799.012 196.682 ops/ms
c.z.h.b.StatementBench.cycleStatement 32 acp thrpt 16 237927.492 4201.623 ops/ms
processor : 0
vendor_id : GenuineIntel
cpu family : 6
model : 58
model name : Intel(R) Core(TM) i7-3517U CPU @ 1.90GHz
stepping : 9
microcode : 0x15
cpu MHz : 800.000
cache size : 4096 KB
physical id : 0
siblings : 4
core id : 0
cpu cores : 2
apicid : 0
initial apicid : 0
fpu : yes
fpu_exception : yes
cpuid level : 13
wp : yes
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx rdtscp lm constant_tsc arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc aperfmperf eagerfpu pni pclmulqdq dtes64 monitor ds_cpl vmx est tm2 ssse3 cx16 xtpr pdcm pcid sse4_1 sse4_2 x2apic popcnt tsc_deadline_timer aes xsave avx f16c rdrand lahf_lm ida arat epb xsaveopt pln pts dtherm tpr_shadow vnmi flexpriority ept vpid fsgsbase smep erms
bogomips : 4789.13
clflush size : 64
cache_alignment : 64
address sizes : 36 bits physical, 48 bits virtual
power management:
Connection pools may be created and configured programmatically, from Java properties, or HOCON format. The most common configuration settings are documented below and a sample properties file is included.
- name
- The pool name. Required.
- minActiveSegments
- The minimum number of active segments. Default 1.
- saturatedAcquireTimeout
- The maximum amount of time to block waiting for an available connection. Default 0ms.
- idleCheckInterval
- The time between idle segment checks. Default 60s.
- segments
- The number of segments. Default 1.
- activeSegments
- The number of segments active on start. Default 1.
- connection.user
- The database user.
- connection.password
- The database password.
- connection.url
- The database connection string.
- connection.testSQL
- SQL used for connection tests.
- connection.debug
- Is connection debug mode turned on?
- connection.testInterval
- The interval between connection tests. Default 60s.
- connection.maxWait
- The maximum amount of time to wait for a database connection before giving up. Default 0s.
- segment.size
- The number of connections in each segment. Required.
- segment.closeConcurrency
- The number of background threads processing connection close. If 0, close blocks in the application thread. Default 0.
- segment.reconnectConcurrency
- The maximum number of concurrent database reconnects. Default 1.
- segment.testOnLogicalOpen
- Should connections be tested when they are acquired? Default false.
- segment.testOnLogicalClose
- Should connections be tested when they are released? Default false.
- segment.acquireTimeout
- The maximum amount of time to wait for a segment connection to become available. Default 0ms.
- segment.activeTimeout
- The maximum amount of time a logical connection may be open before it is forcibly closed. Default 5m.
- segment.connectionLifetime
- The maximum amount of time a physical connection may be open. Default 1h.
- segment.maxReconnectWait
- The maximum amount of time to wait between physical connection attempts on failure. Default 30s.
The build uses Apache Ant and Apache Ivy to resolve dependencies. The following ant tasks are available:
- compile - Compiles the source
- dist - Resolves dependencies, compiles the source, and creates a jar in dist/lib. This is the default task.
- full-dist - Resolves dependencies, compiles the source, creates a jar in dist/lib, and copies dependencies to dist/extlib
- clean - Removes all build files and jars.
Copyright 2014 Attribyte, LLC
Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.