Performance comparison of Stream.toList() and Collectors.toList()

Yesterday, I introduced the Stream enhancement in Java 16, which can be converted to List directly through toList() .

It mainly involves the following conversion methods:

 list.stream().toList();
list.stream().collect(Collectors.toList());
list.stream().collect(Collectors.toUnmodifiableList());

Then, I saw some netizens commented: What is the difference between Stream.toList() and Collectors.toList() ? Which one performs better?

The difference in processing results is actually said in the previous article and video:

• Stream.toList() The returned List is an immutable List and cannot be added, deleted or modified
• Collectors.toList() Returns an ordinary List, which can be added, deleted, or modified
• Collectors.toUnmodifiableList() The returned List is an immutable List and cannot be added, deleted or modified

As for performance, let's test it today to see which one performs better.

 @BenchmarkMode(Mode.All)
@Fork(1)
@State(Scope.Thread)
@Warmup(iterations = 20, time = 1, batchSize = 10000)
@Measurement(iterations = 20, time = 1, batchSize = 10000)
public class BenchmarkStreamToList {

    @Benchmark
    public List<Integer> streamToList() {
        return IntStream.range(1, 1000).boxed().toList();
    }

    @Benchmark
    public List<Integer> collectorsToList() {
        return IntStream.range(1, 1000).boxed().collect(Collectors.toList());
    }

    @Benchmark
    public List<Integer> streamToList() {
        return IntStream.range(1, 1000).boxed().toList();
    }

}

Results report:

 Benchmark                                                                                  Mode  Cnt   Score    Error  Units
BenchmarkStreamToList.collectorsToList                                                    thrpt   20  24.422 ±  0.268  ops/s
BenchmarkStreamToList.collectorsToUnmodifiableList                                        thrpt   20  22.784 ±  0.599  ops/s
BenchmarkStreamToList.streamToList                                                        thrpt   20  31.779 ±  1.732  ops/s
BenchmarkStreamToList.collectorsToList                                                     avgt   20   0.045 ±  0.006   s/op
BenchmarkStreamToList.collectorsToUnmodifiableList                                         avgt   20   0.062 ±  0.035   s/op
BenchmarkStreamToList.streamToList                                                         avgt   20   0.040 ±  0.028   s/op
BenchmarkStreamToList.collectorsToList                                                   sample  445   0.046 ±  0.002   s/op
BenchmarkStreamToList.collectorsToList:collectorsToList·p0.00                            sample        0.039            s/op
BenchmarkStreamToList.collectorsToList:collectorsToList·p0.50                            sample        0.041            s/op
BenchmarkStreamToList.collectorsToList:collectorsToList·p0.90                            sample        0.057            s/op
BenchmarkStreamToList.collectorsToList:collectorsToList·p0.95                            sample        0.073            s/op
BenchmarkStreamToList.collectorsToList:collectorsToList·p0.99                            sample        0.102            s/op
BenchmarkStreamToList.collectorsToList:collectorsToList·p0.999                           sample        0.150            s/op
BenchmarkStreamToList.collectorsToList:collectorsToList·p0.9999                          sample        0.150            s/op
BenchmarkStreamToList.collectorsToList:collectorsToList·p1.00                            sample        0.150            s/op
BenchmarkStreamToList.collectorsToUnmodifiableList                                       sample  460   0.044 ±  0.001   s/op
BenchmarkStreamToList.collectorsToUnmodifiableList:collectorsToUnmodifiableList·p0.00    sample        0.042            s/op
BenchmarkStreamToList.collectorsToUnmodifiableList:collectorsToUnmodifiableList·p0.50    sample        0.044            s/op
BenchmarkStreamToList.collectorsToUnmodifiableList:collectorsToUnmodifiableList·p0.90    sample        0.046            s/op
BenchmarkStreamToList.collectorsToUnmodifiableList:collectorsToUnmodifiableList·p0.95    sample        0.047            s/op
BenchmarkStreamToList.collectorsToUnmodifiableList:collectorsToUnmodifiableList·p0.99    sample        0.051            s/op
BenchmarkStreamToList.collectorsToUnmodifiableList:collectorsToUnmodifiableList·p0.999   sample        0.057            s/op
BenchmarkStreamToList.collectorsToUnmodifiableList:collectorsToUnmodifiableList·p0.9999  sample        0.057            s/op
BenchmarkStreamToList.collectorsToUnmodifiableList:collectorsToUnmodifiableList·p1.00    sample        0.057            s/op
BenchmarkStreamToList.streamToList                                                       sample  655   0.031 ±  0.001   s/op
BenchmarkStreamToList.streamToList:streamToList·p0.00                                    sample        0.030            s/op
BenchmarkStreamToList.streamToList:streamToList·p0.50                                    sample        0.031            s/op
BenchmarkStreamToList.streamToList:streamToList·p0.90                                    sample        0.032            s/op
BenchmarkStreamToList.streamToList:streamToList·p0.95                                    sample        0.033            s/op
BenchmarkStreamToList.streamToList:streamToList·p0.99                                    sample        0.035            s/op
BenchmarkStreamToList.streamToList:streamToList·p0.999                                   sample        0.037            s/op
BenchmarkStreamToList.streamToList:streamToList·p0.9999                                  sample        0.037            s/op
BenchmarkStreamToList.streamToList:streamToList·p1.00                                    sample        0.037            s/op
BenchmarkStreamToList.collectorsToList                                                       ss   20   0.043 ±  0.001   s/op
BenchmarkStreamToList.collectorsToUnmodifiableList                                           ss   20   0.045 ±  0.004   s/op
BenchmarkStreamToList.streamToList                                                           ss   20   0.031 ±  0.001   s/op

From the report we can see:

• Throughput: streamToList > collectorsToList > collectorsToUnmodifiableList
• Average time: streamToList > collectorsToList > collectorsToUnmodifiableList
• p0.9999 time consuming: streamToList > collectorsToUnmodifiableList > collectorsToList
• Cold start time: streamToList > collectorsToList > collectorsToUnmodifiableList

Therefore, Stream.toList() performs better than Collectors.toList() and Collectors.toUnmodifiableList() in every respect.

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To zoom in some more data, try:

 @Benchmark
public List<Integer> streamToList() {
  return IntStream.range(1, 10000).boxed().toList();
}

@Benchmark
public List<Integer> collectorsToList() {
  return IntStream.range(1, 10000).boxed().collect(Collectors.toList());
}

@Benchmark
public List<Integer> streamToList() {
  return IntStream.range(1, 10000).boxed().toList();
}

Results report:

 Benchmark                                                                                  Mode  Cnt  Score   Error  Units
BenchmarkStreamToList.collectorsToList                                                    thrpt   20  2.186 ± 0.162  ops/s
BenchmarkStreamToList.collectorsToUnmodifiableList                                        thrpt   20  2.184 ± 0.042  ops/s
BenchmarkStreamToList.streamToList                                                        thrpt   20  3.538 ± 0.058  ops/s
BenchmarkStreamToList.collectorsToList                                                     avgt   20  0.426 ± 0.004   s/op
BenchmarkStreamToList.collectorsToUnmodifiableList                                         avgt   20  0.469 ± 0.016   s/op
BenchmarkStreamToList.streamToList                                                         avgt   20  0.293 ± 0.008   s/op
BenchmarkStreamToList.collectorsToList                                                   sample   58  0.448 ± 0.049   s/op
BenchmarkStreamToList.collectorsToList:collectorsToList·p0.00                            sample       0.414           s/op
BenchmarkStreamToList.collectorsToList:collectorsToList·p0.50                            sample       0.422           s/op
BenchmarkStreamToList.collectorsToList:collectorsToList·p0.90                            sample       0.458           s/op
BenchmarkStreamToList.collectorsToList:collectorsToList·p0.95                            sample       0.560           s/op
BenchmarkStreamToList.collectorsToList:collectorsToList·p0.99                            sample       1.160           s/op
BenchmarkStreamToList.collectorsToList:collectorsToList·p0.999                           sample       1.160           s/op
BenchmarkStreamToList.collectorsToList:collectorsToList·p0.9999                          sample       1.160           s/op
BenchmarkStreamToList.collectorsToList:collectorsToList·p1.00                            sample       1.160           s/op
BenchmarkStreamToList.collectorsToUnmodifiableList                                       sample   60  0.458 ± 0.004   s/op
BenchmarkStreamToList.collectorsToUnmodifiableList:collectorsToUnmodifiableList·p0.00    sample       0.447           s/op
BenchmarkStreamToList.collectorsToUnmodifiableList:collectorsToUnmodifiableList·p0.50    sample       0.455           s/op
BenchmarkStreamToList.collectorsToUnmodifiableList:collectorsToUnmodifiableList·p0.90    sample       0.471           s/op
BenchmarkStreamToList.collectorsToUnmodifiableList:collectorsToUnmodifiableList·p0.95    sample       0.482           s/op
BenchmarkStreamToList.collectorsToUnmodifiableList:collectorsToUnmodifiableList·p0.99    sample       0.492           s/op
BenchmarkStreamToList.collectorsToUnmodifiableList:collectorsToUnmodifiableList·p0.999   sample       0.492           s/op
BenchmarkStreamToList.collectorsToUnmodifiableList:collectorsToUnmodifiableList·p0.9999  sample       0.492           s/op
BenchmarkStreamToList.collectorsToUnmodifiableList:collectorsToUnmodifiableList·p1.00    sample       0.492           s/op
BenchmarkStreamToList.streamToList                                                       sample   78  0.293 ± 0.012   s/op
BenchmarkStreamToList.streamToList:streamToList·p0.00                                    sample       0.277           s/op
BenchmarkStreamToList.streamToList:streamToList·p0.50                                    sample       0.284           s/op
BenchmarkStreamToList.streamToList:streamToList·p0.90                                    sample       0.309           s/op
BenchmarkStreamToList.streamToList:streamToList·p0.95                                    sample       0.377           s/op
BenchmarkStreamToList.streamToList:streamToList·p0.99                                    sample       0.459           s/op
BenchmarkStreamToList.streamToList:streamToList·p0.999                                   sample       0.459           s/op
BenchmarkStreamToList.streamToList:streamToList·p0.9999                                  sample       0.459           s/op
BenchmarkStreamToList.streamToList:streamToList·p1.00                                    sample       0.459           s/op
BenchmarkStreamToList.collectorsToList                                                       ss   20  0.474 ± 0.133   s/op
BenchmarkStreamToList.collectorsToUnmodifiableList                                           ss   20  0.493 ± 0.099   s/op
BenchmarkStreamToList.streamToList                                                           ss   20  0.325 ± 0.056   s/op

From the report we can see

• Throughput: streamToList > collectorsToList > collectorsToUnmodifiableList
• Average time: streamToList > collectorsToList > collectorsToUnmodifiableList
• p0.9999 time consuming: streamToList > collectorsToUnmodifiableList > collectorsToList
• Cold start time: streamToList > collectorsToList > collectorsToUnmodifiableList

So, even if the elements in the set increase, Stream.toList() still performs better than the method under Collectors in every way.

Well, today's sharing is here, have you learned it?

This video: https://www.bilibili.com/video/BV16Y411F7Pm/

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