Igniters,
Java streams are known to be slower and cause more GC pressure than an
equivalent loop.
Below is a simple filter/map/reduce scenario (code [1]):
* Benchmark Mode Cnt
Score Error Units
* StreamVsLoopBenchmark.loopSum thrpt 3
7987.016 ± 293.013 ops/ms
* StreamVsLoopBenchmark.loopSum:·gc.alloc.rate thrpt 3
≈ 10⁻⁴ MB/sec
* StreamVsLoopBenchmark.loopSum:·gc.count thrpt 3
≈ 0 counts
* StreamVsLoopBenchmark.streamSum thrpt 3
1060.244 ± 36.485 ops/ms
* StreamVsLoopBenchmark.streamSum:·gc.alloc.rate thrpt 3
315.819 ± 10.844 MB/sec
* StreamVsLoopBenchmark.streamSum:·gc.count thrpt 3
55.000 counts
Loop is several times faster and does not allocate at all.
1. Performance is one of the most important features of our product.
2. Most of our APIs will be on the hot path.
One can argue about performance differences in real-world scenarios,
but increasing GC pressure just to make the code a little bit nicer is
unacceptable.
I propose to ban streams usage in the codebase (except for the tests).
Thoughts, objections?
[1] https://gist.github.com/ptupitsyn/5934bbbf8f92ac4937e534af9386da97
