java - What does @Group and @GroupThreads refer to in jmh? -

i have been looking @ way jmh implements "multithreaded" benchmarks. understanding, annotations @group("identifier") , @groupthreads(thread_number) enable running in parallel benchmarks within same group.

@benchmark @group("parallel") @groupthreads(1) public void benchmark_1() {     while(true) {} }  @benchmark @group("parallel") @groupthreads(1) public void benchmark_2() {     while(true) {} } 

using cpu monitor, 2 cpu's used. know how runner interpret annotations.

have tried reading javadocs? not answering question?

e.g. @group says:

 * <p>multiple {@link benchmark} methods can bound in execution group  * produce asymmetric benchmark. each execution group contains of 1  * or more threads. each thread within particular execution group executes  * 1 of {@link group}-annotated {@link benchmark} methods. number of  * threads executing particular {@link benchmark} defaults single thread,  * , can overridden {@link groupthreads}.</p>  *  * <p>multiple copies of execution group may participate in run, ,  * number of groups depends on number of worker threads requested.  * jmh take requested number of worker threads, round execution  * group size, , distribute threads among (multiple) groups.  * among other things, guarantees fully-populated execution groups.</p>   * <p>for example, running {@link group} 2 {@link benchmark} methods,  * each having {@link groupthreads}(4), run 8*n threads, n  * integer.</p> 

so, @group produces asymmetric benchmark, @groupthreads controls distribution of threads within group (-tg ... in cli dubs it). @threads how many threads run in total (-t ... in cli dubs it).