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README.md

HikariCP Ultimate JDBC Connection Pool  We came, we saw, we kicked its ass

There is nothing faster. There is nothing more reliable. There is nothing more correct.

Are you using DBCP, C3P0 or BoneCP? Stop.

TL;DR

Let's look at some performance numbers. HikariCP was only compared to BoneCP because, really, DBCP and C3P0 are old and slow and I don't know why anyone would use them.

MixedBench

This is the so called "Mixed" benchmark, and it executes a representative array of JDBC operations in a realistic mix. We think median is the number to pay attention to, rather than average (which can get skewed). Median meaning 50% of the iterations were slower, %50 were faster. 200 threads we started, and the underlying connection pool contained 100 connections.

Pool Med (ms) Avg (ms) Max (ms)
BoneCP 2155 1541 3265
HikariCP 230 139 526

A breakdown of the mix operations is:

Operation Invocations
DataSource.getConnection() 1000
PreparedStatement.prepareStatement() 200,000
PreparedStatement.setInt() 30,000,000
PreparedStatement.addBatch() 10,000,000
PreparedStatement.executeBatch() 100,000
PreparedStatement.executeQuery() 100,000
PreparedStatement.close() 200,000
ResultSet.next() 10,000,000
ResultSet.getInt() 10,000,000
ResultSet.close() 100,000
Connection.close() 1000

The JVM JIT was "warmed up" with a single run through, then 4 runs were made from which the run with the lowest median time was chosen. The run with the lowest median was also the run with the lowest average -- so don't think we're skewing the results.

The benchmark was run using a stub (nop) implementation of an underlying DataSource, Connection, PreparedStatement, and ResultSet, so the driver was taken completely out of the equation so that the performance and overhead of the pools themselves could be measured.

The test was performed on an Intel Core i7 (3770 Ivy Bridge) 3.4GHz iMac with 32GB of RAM. The JVM benchmark was run with: -server -XX:+UseParallelGC -Xss256k.

In Summary

200 threads ran 60,702,000 JDBC operations each, HikariCP did this in a median of 230ms per thread.

(In)correctness

Sometimes "correctness" is objective, and sometimes it is subjective. One example of objective incorrectness in BoneCP is ResultSet handling. Every connection pool needs to wrap the underlying Connection, Statement, CallableStatement, and PreparedStatement, and ResultSet classes. However, BoneCP does not wrap ResultSet.

ResultSet must be wrapped, because ResultSet.getStatement() must return the wrapped Statement that generated it, not the underlying Statement. Hibernate 4.3 for one relies on this semantic.

If BoneCP were to wrap ResultSet, which comprises 20,100,000 of the 60,702,000 operations in MixedBench, its performance numbers would be far poorer. Also take note that HikariCP does properly wrap ResultSet and still achives the numbers above.

One example of subjective incorrectness -- being my personal opinion -- is that BoneCP does not test a Connection immediately before dispatching it from the pool. It is through this mechanism that it achives some of it's speed. In my opinion, this one "flaw" (or "feature") renders BoneCP insuitable for Production use. The number one responsibility of a connection pool is to not give out possibly bad connections.

Over on the BoneCP site, you can find a comparison of BoneCP vs. DBCP and C3P0. DBCP and C3P0, as poor as they are, at least are performing aliveness tests before dispatching connections. So, it's not really a fair comparison. HikariCP supports the JDBC4 Connection.isValid() API, which for many drivers provides a non-query based aliveness test.

A particularly silly "benchmark" on the BoneCP site starts 500 threads each performing 100 DataSource.getConnection() / connection.close() calls with 0ms delay between. Who does that? The typical "mix" is dozens or hundreds of JDBC operations between obtaining the connection and closing it (hence the "MixBench") above. But ok, we can run this "benchmark" too (times in Microseconds):

Pool Med (μs) Avg (μs) Max (μs)
BoneCP 19467 8762 30851
HikariCP 76 65 112

The times are per-thread reflecting 100 getConnection()/close() operations with no wait between.