Leve.Iteration @TearDown method called one too many times

[Alex Averbuch]

FYI, I'm using:

        <dependency>
            <groupId>org.openjdk.jmh</groupId>
            <artifactId>jmh-core</artifactId>
            <version>1.1.3</version>
        </dependency>


On Mon, Jul 25, 2016 at 3:27 PM, Alex Averbuch <
alex.averbuch at neotechnology.com> wrote:

> Hi,
> I have a benchmark for measuring database index creation.
>
> Summary:
>   * It is an expensive operation (5+ seconds per invocation), so
> Mode.SingleShotTime is used
>   * The database runs 5 warmup iterations & 5 measurement iterations
>   * Each iteration must create an index from scratch, so the index must be
> dropped/deleted between iterations
>   * To delete the index after each iteration a Level.Iteration @TearDown
> method is used. Inside this method the index is dropped
>
> Problem:
>   * It appears as though the Level.Iteration @TearDown method is being
> called 1 more time than the @Benchmark method
>   * This causes the database (and benchmark) to crash, because the
> database tries to delete an index that does not exist
>
> When executing the benchmark code at the bottom of this email, the
> following is written to console:
>
> # Run progress: 0.00% complete, ETA 00:00:00
> # Fork: 1 of 1
> # Warmup Iteration   1:
> CREATE
> DROP
> # Warmup Iteration   2:
> CREATE
> DROP
> # Warmup Iteration   3:
> CREATE
> DROP
> # Warmup Iteration   4:
> CREATE
> DROP
> # Warmup Iteration   5:
> CREATE
> DROP
> Iteration   1:
> CREATE
> DROP
> Iteration   2:
> CREATE
> DROP
> Iteration   3:
> CREATE
> DROP
> Iteration   4:
> CREATE
> DROP
> Iteration   5:
> CREATE
> DROP
> DROP                                   <--------- NOTICE THIS ADDITIONAL
> "DROP"
>
>
>
> Does this (extra DROP) make sense?
> Is there any way to prevent it from happening?
> Thanks in advance!
>
>
> @State( Scope.Benchmark )
> public class CreateIndex
> {
>     protected Database db;
>
>     @Setup
>     public void setUp()
>     {
>         db = new Database();
>         // populate db
>     }
>
>     @TearDown
>     public void tearDown()
>     {
>         db.shutdown();
>     }
>
>     @TearDown( Level.Iteration )
>     public void dropIndex()
>     {
>         System.out.println("DROP");
>         try ( Transaction tx = db.beginTx() )
>         {
>             // drop index
>             tx.success();
>         }
>     }
>
>     @Benchmark
>     @BenchmarkMode( Mode.SingleShotTime )
>     public void createIndex()
>     {
>         System.out.println("CREATE");
>         try ( Transaction tx = db.beginTx() )
>         {
>             // create index
>             tx.success();
>         }
>     }
> }
>